Dr. Jeff Masters' WunderBlog

Typhoon Mirinae less destructive than feared for Philippines

By: JeffMasters, 2:15 PM GMT en Octubre 31, 2009

Typhoon Mirinae blew through the Philippines' Luzon Island yesterday as a borderline Category 1 to 2 typhoon with top winds of 95 - 100 mph. Due to the rapid forward motion of the typhoon and a sharp decrease in the storm's organization just prior to landfall, rainfall amounts from the typhoon were less than six inches over Luzon. The eye of Mirinae passed over the capital of Manila, where winds peaked at minimal tropical storm force, 39 mph, with gusts to 56 mph, at 6 am local time Saturday. Nearby weather stations recorded sustained winds as high as 44 mph, and rainfall amounts of 2 - 3 inches. Though Mirinae is being blamed for at least 11 deaths, with 7 people still missing, it's fair to say that the typhoon largely spared the Philippines. The Manila Bulletin is reporting that a tornado (called an "ipo-ipo" there) injured ten and destroyed some 60 houses in Cavite and Ternate as Mirinae swept through.

Mirinae, now just a tropical storm with 65 mph winds, is currently over the South China Sea. Mirinae is expected to make landfall in south-central Vietnam near 00 UTC on Monday, November 2. As Mirinae approaches Vietnam, wind shear will increase, sea surface temperatures and the total heat content of the ocean will sharply decrease, and the storm will encounter cooler, more stable air. These negative influences should make Mirinae a 45 - 55 mph tropical storm at landfall in Vietnam.


Figure 1. Filipinos watch the onslaught of Typhoon Mirinae on Saturday. Image credit: Jim Edds. His extremestorms.com website has images and videos from the landfall of Mirinae.

Quiet in the Atlantic
A non-tropical low pressure system in the middle Atlantic Ocean, near 30N 50W, 700 miles east of Bermuda, has cut off from the jet stream. This low will slowly wander westward toward Bermuda over the next three days. It is possible that the low will spend enough time over water to acquire some tropical characteristics and become Subtropical Storm Ida, though I put the chances at low, less than 30%. SSTs are 25 - 26° C in the region, which is barely warm enough to support a tropical storm. Wind shear is high, 30 - 50 knots, and there is a large amount of dry air to the west of the low, so no development will occur today. The storm is expected to recurve to the north well east of Bermuda on Tuesday.

None of the reliable computer models is calling for tropical storm development in the Atlantic over the next seven days. The GFS and NOGAPS models are calling for a tropical storm to form off the Pacific coast of Mexico near the Guatemala border by the middle of next week, and it is possible that this development could occur on the Atlantic side of Central America instead, as suggested by the Canadian model.

Jeff Masters

Hurricane

Updated: 6:30 PM GMT en Agosto 18, 2011

Permalink

Tornado rips Shreveport; Typhoon Mirinae deluging the Philippines

By: JeffMasters, 2:01 PM GMT en Octubre 30, 2009

Between one and five tornadoes touched down in northwest Louisiana and southwest Arkansas on Thursday. The most damaging tornado hit Shreveport, Louisiana at 5:15 pm EDT, ripping the steeple off of a church and hurling it onto a car. No fatalities were blamed on the tornadoes, though one man was killed when he drove his car into a fallen tree. The cold front responsible for spawning the severe weather will be over Alabama today, where the Storm Prediction Center is forecasting a slight chance of severe thunderstorms. Rainfall amounts from the storm exceeded six inches in many regions (Figure 1), and the cold front draped across the center of the country is responsible for flood warnings for a wide swath, from Texas to Illinois. See our severe weather map or consult our wundermap with the USGS River layer turned on to see where flooding is occurring.


Figure 1. Estimated rainfall from the line of storms that passed through northern Louisiana yesterday and today.

Colorado digs out
The Denver, Colorado area continues to dig out from the biggest October snowstorm to affect the region since 1997. The town of Pinecliff in the mountains just northwest of Denver recorded 46 inches of snow from the storm.

Typhoon Mirinae deluges the Philippines
Category 2 Typhoon Mirinae's deluge has begun over the Philippines' Luzon Islands, as the storm's eye nears the east coast of the island. Mirinae--who's name is taken from the Korean word for "Milky Way"--did not intensify, and now appears to be suffering from land interaction, since the southwest portion of the typhoon's circulation is now over land. The latest infrared satellite loops show no eye, a decrease in the storm's organization, and warming of the cloud tops of Mirinae's eyewall clouds--all indicative of weakening. Satellite estimates of Mirinae's intensity declined a bit over the past twelve hours, and it appears likely that Mirinae will be a Category 1 typhoon with 80 - 90 mph winds at landfall near 18 UTC (2 pm EDT) today. Mirinae's primary threat will be heavy rain, and microwave imagery shows that the typhoon's heaviest rains of one inch per hour lie in the southern eyewall. With the eye expected to track over or slightly south of the capital of Manila, this means that Mirinae's heaviest rains of 8 - 12 inches will fall just south of Manila, with 4 - 8 inches expected over the city (Figure 3). The ground is still flooded and the dams brimming full from the previous two typhoons to hit the Philippines over the past five weeks, so Mirinae will probably cause much heavier damage than is usual for a typhoon of its intensity. Flood water from the September 26 deluge of Typhoon Ketsana is still standing in the streets of some suburban areas of Manila, where more than one million people are living in flooded districts. The combined death tolls from Typhoon Ketsana and Typhoon Parma in the Philippines this year now exceed 1,000, and Mirinae will undoubtedly add to that figure. However, Manila is more prepared for this storm than it was for Typhoon Ketsana, and I am hopeful that the death toll from Mirinae will be far less. Mirinae is expected to emerge over the South China Sea tomorrow and strike south-central Vietnam on Monday. With wind shear expected to steadily increase over the storm, and the typhoon disrupted from its passage over Luzon, it is unlikely that Mirinae would hit Vietnam as anything stronger than a tropical storm with 55 mph winds.

Extreme storm photographers Jim Edds and James Reynolds are in Manila for the arrival of Mirinae, and have posted a video of the surf along the shore from the typhoon at the extremestorms.com website.


Figure 2. MODIS visible satellite image of Typhoon Mirinae at 05 UTC Friday, October 20. A the time, Mirinae was a Category 2 typhoon with 105 mph winds. Image credit: NASA MODIS Rapid Response System.


Figure 3. Rainfall forecast for Typhoon Mirinae for the 24-hour period ending at 06 UTC Saturday October 30, 2009. Mirinae is expected to dump 8 - 12 inches of rain along a narrow swath near its core, passing just south of the capital of Manila. Image credit: NOAA/NESDIS.

Quiet in the Atlantic
There are no threat areas in the Atlantic to discuss, and the the Caribbean is dominated by dry air and high wind shear. A non-tropical low pressure system in the middle Atlantic Ocean, near 32N 50W, is cutting off from the jet stream and will slowly wander westward toward Bermuda over the next 3 - 4 days. It is possibly that the low will spend enough time over water to acquire some tropical characteristics and become Subtropical Storm Ida. The storm could bring high winds to Bermuda on Monday. Elsewhere in the Atlantic, none of the computer models is calling for tropical storm development over the next seven days. Most of the models are calling for a tropical storm to form off the Pacific coast of Mexico near the Guatemala border by the middle of next week.

Jeff Masters

Hurricane

Updated: 6:30 PM GMT en Agosto 18, 2011

Permalink

Philippines brace for Typhoon Mirinae; big snowstorm wallops Colorado

By: JeffMasters, 2:14 PM GMT en Octubre 29, 2009

Category 2 Typhoon Mirinae continues to trek westward towards the Philippine Islands, but has not intensified and may be weaker than advertised. Latest infrared satellite loops show no eye, and little change to the areal extent, organization, and temperature of the cloud tops over the past six hours. Satellite estimates of Mirinae's intensity declined over the past twelve hours, and support a Category 1 typhoon. Microwave imagery shows no eyewall, and it appears wind shear has managed to disrupt the inner core. Wind shear remains a moderate 15 knots, and the ocean temperatures are very warm, 29°C. With environmental conditions forecast not forecast to undergo any major changes over the next two days, Mirinae should be somewhere between a Category 1 and Category 3 typhoon when it makes landfall on Friday afternoon (EDT). The main threat from the storm will be heavy rains, and Mirinae is currently producing maximum rains of about eight inches per day along its track (Figure 1). The mountains of Luzon Island will cause additional uplift and lead to higher rain amounts as the typhoon passes over, and rain amounts in excess of twelve inches near Mirinae's core will cause serious flooding and dangerous mudslides. The ground is still flooded and the dams brimming full from the previous two typhoons to hit the Philippines over the past five weeks, so Mirinae will probably cause much heavier damage than is usual for a typhoon of its intensity. The typhoon is forecast to pass within 200 miles of the capital of Manila, where flood water from the September 26 deluge of Typhoon Ketsana is still standing in the streets of some suburban areas. More than one million people are living in flooded districts near Manila.


Figure 1. Rainfall forecast for Typhoon Mirinae for the 24-hour period ending at 06 UTC Friday October 30, 2009. Mirinae is expected to dump 8+ inches of rain along a narrow swath near its core. Image credit: NOAA/NESDIS.

Quiet in the Atlantic
There are no threat areas in the Atlantic to discuss, and the the Caribbean is dominated by dry air and high wind shear. However, a non-tropical low pressure system is expected to develop in the middle-Atlantic on Monday, and may spend enough time over water to acquire some tropical characteristics and become Subtropical Storm Ida. Wunderblogger Weather456 has a nice discussion of the meteorology of this storm, which may bring high winds to Bermuda next week. Elsewhere in the Atlantic, none of the computer models is calling for tropical storm development over the next seven days. Several models are calling for a tropical storm to form off the Pacific coast of Mexico by the middle of next week.

Major snowstorm wallops Colorado
The season's first major snowstorm is walloping Colorado, Wyoming, and western Nebraska and South Dakota today. In the mountain regions just west of Denver, up to 38 inches of snow has fallen, with another 4 - 12 inches possible today. It was the biggest October snowstorm in the Denver region since 1997.

Portlight's Paul Timmons on the Barometer Bob Show Tonight
Portlight's Paul Timmons will be appearing live tonight (Thursday) at 8pm EDT on the Barometer Bob Show, an Internet radio show that I have appeared on several times in the past. Be sure to catch his discussion of how Portlight got started, where they're going, and what's new!

Jeff Masters

Hurricane

Updated: 6:31 PM GMT en Agosto 18, 2011

Permalink

Winter forecast for the U.S.; Typhoon Mirinae threatens the Philippines

By: JeffMasters, 1:18 PM GMT en Octubre 28, 2009

Expect a warmer than average winter in the north central U.S., and cooler than average over the Southeast U.S., according the latest winter forecast issued last Thursday by the National Oceanic and Atmospheric Administration (NOAA). Wetter than average conditions are likely from Texas across the Gulf Coast and across the Southeastern U.S., with California also more likely than not to get increased precipitation. Those are the temperature patterns observed about 60% of the time in the U.S. during an El Niño event. As I discussed in yesterday's post, El Niño--the periodic warming of the equatorial Eastern Pacific Ocean that occurs every 2 - 7 years--has just crossed the threshold from weak to moderate, meaning that that ocean temperatures are 1.0 - 1.5°C above average along the Equator off the Pacific coast of South America. Moderate El Niño conditions are expected to continue through the winter months of December - February, with some climate forecast models predicting intensification into a strong El Niño. The presence of all that warm water alters the path of the jet stream, affecting the winter weather across a large portion of the globe. In particular, the southern branch of the jet stream--called the subtropical jet--is expected to intensify, bringing increased cloudiness and storminess along its usual path, from south Texas, across the Gulf Coast, through Florida, and into South and North Carolina. The increased cloudiness typically leads to cooler temperatures and more rainfall across the entire Southeastern U.S., especially Florida and South Texas. This should give significant drought relief to the South Texas.

The heat in the Eastern Pacific Ocean during an El Niño winter makes for more intense mid-latitude low pressure systems off the U.S. west coast. As a result, these storms are able to pump abnormally warm air into western Canada, Alaska and the extreme northern portion of the contiguous United States. With this warm air typically comes drier than normal conditions. With the forecast for Vancouver, Canada--home to the February 12 - 28 2010 Winter Olympics this winter--calling for warmer and drier conditions than average, lack of snow may be a problem for some of the venues. If the El Niño manages to strengthen to the strong category (greater than 1.5°C), California will most likely experience much increased precipitation, and the North Central U.S. will see winter temperatures 3 - 6°F above average. NOAA maintains a web page that shows the typical U.S. temperature and precipitation patterns for any season for historical EL Niño and La Niña events. Golden Gate Weather takes the idea a step further, and separates the effects by whether it is a weak, moderate, or strong El Niño.

How good is this forecast?
Not all El Niño winters follow the usual pattern. For instance, the El Niño winter of 2004 - 2005 had above-average temperatures over the entire U.S., and drier than average conditions across Florida, which are the opposite of the typical pattern observed during most El Niño winters (Figures 1 and 2). There are other natural variations in the weather and climate, such as the Pacific Decadal Oscillation (PDO) and the North Atlantic Oscillation (NAO) that can act to counteract or re-enforce the typical El Niño pattern. In addition, the climate is changing due to human-caused emissions of greenhouse gases, and its possible that what we've come to expect an El Niño winter to be like based on past history will no longer be true as often. It is likely the dramatic loss of arctic sea ice in recent years is already significantly affecting precipitation and temperature patterns during winter, and that the patterns we expect to see during El Niño winters are now changing to a new mode. I'll discuss the possibilities in a future post.


Figure 1. Wintertime (December - February) temperatures for the U.S. over the past nine years. The past three winters with El Niño conditions (yellow highlighted years) were 2003, 2005, and 2007. The 2003 El Niño was moderate strength, and 2005 and 2007 were weak. Image credit: National Climatic Data Center.

Figure 2. Wintertime (December - February) precipitation for the U.S. over the past nine years. The past three winters with El Niño conditions (yellow highlighted years) were 2003, 2005, and 2007. The 2003 El Niño was moderate strength, and 2005 and 2007 were weak. Image credit: National Climatic Data Center.

Philippines prepare for Typhoon Mirinae
Category 2 Typhoon Mirinae continues to trek westward towards the Philippine Islands, but appears to have leveled out in intensity. Latest infrared satellite loops show a large, well organized cloud pattern, but an eye is not evident, and the areal extent, organization, and temperature of the cloud tops has not changed much over the past six hours. Satellite estimates of Mirinae's intensity have held steady over the past twelve hours. Wind shear is a moderate 15 knots, and the ocean temperatures are very warm, 29°C. These warm waters extend to great depth, and the Tropical Cyclone Heat Potential (TCHP) is 80 - 100 kJ/cm^2 along Mirinae's entire path to the Philippines. Values of TCHP in excess of 90 kJ/cm^2 are frequently associated with rapid intensification. With wind shear expected to remain in the low to moderate range over the next three days, intensification of Mirinae into a major Category 3 or higher typhoon before its expected landfall at 06 UTC October 31 on Luzon Island is a good possibility.


Figure 4. Mirinae on October 27, 2009, as a tropical storm with 55 mph winds. Image credit: NASA.

Quiet in the Atlantic
There are no threat areas in the Atlantic to discuss, and the the Caribbean is dominated by dry air and high wind shear. However, the extreme Southwestern Caribbean near the coast of Panama is expected to gradually moisten early next week, and several recent runs of the GFS and NOGAPS models suggested that a tropical depression could form in the Southwest Caribbean off the coast of Panama 7 - 8 days from now.

Next post
In tomorrow's port, I'll discuss the impact of El Niño on wintertime tornado activity in Florida, plus have an update on the Philippines typhoon, and the latest model predictions of a possible tropical depression in the Caribbean next week.

Jeff Masters

Hurricane

Updated: 6:31 PM GMT en Agosto 18, 2011

Permalink

El Niño intensifies from weak to moderate; Phillippines under the gun again

By: JeffMasters, 1:57 PM GMT en Octubre 27, 2009

El Niño conditions have strengthened in recent weeks, crossing the threshold from "weak" to "moderate", according to data compiled by NOAA's Climate Prediction Center. NOAA defines "moderate" El Niño conditions as existing when sea surface temperature (SST) departure from average in the equatorial Eastern Pacific (the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region") warms above 1.0°C. According to the latest time-series plot of "Niña 3.4 region" SSTs (Figure 1), we crossed that threshold last week. Monthly average SSTs will have to remain above 1.0°C for five consecutive months in order for this to be considered a "moderate" El Niño event. The ongoing intensification of El Niño could have major impacts on this winter's weather.


Figure 1. Departure of sea surface temperature (SST) from average for the past two years along the equatorial Eastern Pacific (the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region"). Moderate strength El Niño conditions occur when the Niña 3.4 anomaly exceeds 1.0°C, which occurred last week (red arrow). Weak El Niño conditions (Niña 3.4 anomaly between 0.5 - 1.0°C) were present from early June to mid-October. Image credit: NOAA Climate Prediction Center.

The intensification of El Niño is due to a combination of events in the ocean and the atmosphere. In the ocean, a slow-moving wave of water more than 5°C (9°F) warmer than average is progressing from west to east along the Equator (Figure 2). This wave, known as a "Kelvin" wave, is focused at a depth of 150 meters, but also affects surface waters. The Kelvin wave was at 175W on October 1, and is now near 140W, so it is traveling east at about 4 mph (100 miles/day). At the ocean surface, a burst of west-to-east winds near the Date Line has weakened the trade winds (Figure 3), which blow the opposite direction--east to west. The trade winds have weakened by 1 - 2 m/s over the past few weeks, allowing the Kelvin wave to push warm water eastward towards South America. The result of this interplay between ocean and air is an intensification of El Niño conditions from weak to moderate.


Figure 2. Animation of the ocean temperatures (top) and departure of ocean temperatures from average (bottom) as a function of depth along the Equator in the equatorial Eastern Pacific. The left side of the image is near Australia, and the right side is near the coast of South America. At the beginning frame in the bottom image on October 5, an ocean Kelvin wave is apparent at a depth of 150 meters, where the ocean temperature is up to 3°C above average (yellow colors). The wave travels eastwards at about 100 miles/day. By the final frame (October 25), the Kelvin wave has warmed to a temperature 5°C above average (orange colors). The Kelvin wave is helping to push the warm water at the surface to the east, as seen in the progression of the red and orange colors eastwards in the top image. I constructed the animation using the free ImageMagick package on a Linux machine, using data plotted up from the NOAA's Tropical Atmospheric Ocean (TAO) project web page.


Figure 3. Top: Sea Surface temperatures (colors) along the Equator between New Guinea and South America, with surface wind vectors overlaid. Note that there is a burst of westerly winds near the Date Line, 180W. This westerly wind burst is weakening the trade winds, which blow the opposite direction, east-to-west, over the ocean between the Date Line and the coast of South America. Bottom: Departure of wind speed from average along the Equator shows the effect of the westerly wind burst, which has weakened the trade winds at the surface by 1 - 2 m/s along a large swath of ocean near the Equator. The reduction in trade winds allows the warm water to the west to slosh eastwards, intensifying El Niño. Image credit: NOAA's Tropical Atmospheric Ocean (TAO) project web page.

Quiet in the Atlantic
There are no threat areas in the Atlantic to discuss, and none of the computer models is calling for tropical storm formation over the next seven days. This should be a quiet week in the region we need to be most concerned about for a late-season hurricane, the Western Caribbean. Wind shear is forecast to be marginal for tropical storm development this week, and most of the Caribbean is very dry at present. One possible area of concern early next week may be near Bermuda, where the models indicate a large non-tropical low may cut off from the jet stream 6 - 7 days from now. This low could potentially remain over warm waters long enough to acquire tropical characteristics and become Subtropical Storm Ida. Such a storm would only be a threat to Bermuda.

Philippines under the gun yet again
The typhoon-weary Philippine Islands have a new worry--Tropical Storm Mirinae is strengthening quickly east of the islands, and could be a typhoon later today. Latest infrared satellite loops show a large and expanding region of intense thunderstorms with very cold cloud tops, with well-developed spiral banding and excellent upper-level outflow developing. Wind shear is a moderate 15 knots, and the ocean temperatures are very warm, 29°C. These warm waters extend to great depth, and the Tropical Cyclone Heat Potential (TCHP) is 80 - 100 kJ/cm^2 along Mirinae's entire path to the Philippines. Values of TCHP in excess of 90 kJ/cm^2 are frequently associated with rapid intensification, and I expect Mirinae will be a major Category 3 or higher typhoon by Thursday. Mirinae is expected to track westward and hit the Philippines' Luzon Island on Saturday. With wind shear expected to remain in the low to moderate range, the models fairly united about a westward track over the Philippines, and plenty of ocean heat to feed off, the odds certainly favor a strike by Mirinae at Category 1 or higher strength on hard-hit Luzon.


Figure 2. Tropical Storm Mirinae, as it passed north of the Guam radar station last night.

Statisticians reject global cooling
An interesting exercise was conducted by the Associated Press (AP), who gave global average temperature data for the past 130 years to a group of independent statisticians, and told them to analyze the data without telling them what the data represented. These experts concluded that the data showed a distinct decades-long upward trend in the numbers, and no significant drop in the past ten years. This is not too surprising, since no scientific studies in peer-reviewed scientific journals have supported the idea that the globe is cooling. The AP exercise was the lead story in this morning's on-line version of the MSNBC news. Dr. Ricky Rood's climate change blog has an interest analysis of global warming and cooling trends, and how natural variability over years or decades can mask long-term trends. With El Niño cranking up to moderate levels heading into 2010, there's at least a 50/50 chance that year will end up beating 2005/1998 as the warmest year on record, putting the "global cooling" hype to rest for a few years.

Second Annual Portlight Honor Walk
When:
Saturday, December 5, 2009 or Sunday, December 6, 2009

What:
A nationwide grassroots event to raise funds for and awareness of Portlight's ongoing efforts specifically aimed at providing Christmas presents for kids and families devastated by the recent Atlanta floods, South Carolina wildfires, American Samoa tsunami, and other disasters that may occur.

Why:
Un-served, underserved and forgotten people are depending on us.

How:
We need one hundred people across the country to commit to walking one mile on this day, and to raise at least $300.00 in sponsorship from friends, family, co-workers, neighbors, etc. Participants can choose where to walk--it can be the park, the mall the neighborhood--anywhere you choose. The first 100 participants to raise at least $300 will receive a commemorative T-Shirt.

To register, simply e-mail your intention to participate at paul@portlight.org

Check the Portlight featured Weather Underground Blog regularly for updates!

The Honor Walk Sponsor Form available here will help you keep track of funds and pledges:
http://www.portlight.org/images/walkerform.pdf

Portlight's Paul Timmons on the Barometer Bob Show Thursday night
Portlight's Paul Timmons will be appearing live this Thursday at 8pm EDT on the Barometer Bob Show, an Internet radio show that I have appeared on several times in the past. Be sure to catch his discussion of how Portlight got started, where they're going, and what's new!

Next post
I'll have a new post on Wednesday, when I'll discuss how the recent intensification of El Niño may affect winter in the U.S.

Jeff Masters

Hurricane

Updated: 6:31 PM GMT en Agosto 18, 2011

Permalink

A quiet week for the Atlantic; another typhoon for the Philippines?

By: JeffMasters, 1:51 PM GMT en Octubre 26, 2009

There are no threat areas in the Atlantic to discuss, and none of the computer models is calling for tropical storm formation over the next seven days. This should be a quiet week in the region we need to be most concerned about for a late-season hurricane--the Western Caribbean. Wind shear is forecast to be marginal for tropical storm development this week, and most of the Caribbean is very dry. However, next week moisture will be on the increase and wind shear is expected to be low enough to support tropical storm development, so we will need to be more alert for tropical storm development then. I have a sense that this hurricane season may not be over yet. Wind shear hasn't risen to the high levels we usually see by this time of year, and the waters are still very warm in the Western Caribbean. The past ten years have seen five hurricanes (four of them major hurricanes) form in the Caribbean later than today's date. The five storms were Category 4 Paloma, which became a hurricane on November 7, 2008; Category 1 Noel, which became a hurricane on November 2, 2007; Category 3 Beta, which became a hurricane on October 29, 2005; Category 4 Michelle, which became a hurricane on November 2, 2001; and Category 4 Lenny, which became a hurricane on November 15, 1999.


Figure 1. This morning's water vapor image of the Caribbean shows plenty of dry air in the regions of the Western Caribbean where late-season tropical tropical storm development usually occurs. Image credit: NOAA/SSD.

Another typhoon for the Philippines?
The typhoon-weary Philippine Islands have a new worry--Tropical Depression 23 has formed east of the islands, and appears likely to develop into a typhoon that will threaten the Philippines this weekend. The Philippines got a major reprieve this past weekend, when Super Typhoon Lupit weakened and swerved out to sea unexpectedly, missing the islands.

Next post
I'll have a new post on Tuesday, when I'll present the forecast for winter in the U.S.

Jeff Masters

Hurricane

Permalink

The Atlantic is quiet; a remarkable flu map

By: JeffMasters, 3:28 PM GMT en Octubre 24, 2009

An area of disturbed weather over the Bahama Islands associated with a surface trough of low pressure has become disorganized, thanks to the presence of a large amount of dry air. This disturbance will get absorbed by a cold front Sunday and is not a threat to develop. The Hurricane Hunter mission scheduled to fly into the disturbance this afternoon has been canceled. There are no other threat areas in the Atlantic to discuss, and none of the computer models is calling for tropical storm formation over the next seven days.

Flu season comes early
As you've probably heard, there's an H1N1 flu pandemic going on. Here in Michigan, flu hit big time this week, with absentee rates hitting 30% in many school districts. Wunderground has a flu map that we update each week (Figure 1), and it's a remarkable-looking one today. All but four states have gone red (widespread flu, the highest outbreak level). I doubt the flu map has looked like this since 1968, the last time a flu pandemic swept the globe. For those of you who've never visited our flu map page, a typical peak flu outbreak occurs in February or March, and at most twenty states are colored red.


Figure 1. It's safe to say that the U.S. is in the midst of a flu pandemic--just four states are not experiencing widespread outbreaks of flu.

Next post
I'll have a new post on Monday.

Jeff Masters

Hurricane

Permalink

Bahamas disturbance 95L not organizing

By: JeffMasters, 6:51 PM GMT en Octubre 23, 2009

An area of disturbed weather over the central Bahama Islands associated with a surface trough of low pressure was designated Invest 95L by NHC this morning, and has the potential for some slow development over the next two days, as it heads west-northwest towards Southeast Florida. An ASCAT pass at 10:21am EDT this morning showed a center of circulation between Cuba and the central Bahamas, with top winds of 25 mph in the heaviest thunderstorms, to the north of the Bahamas. Recent satellite loops show a modest amount of heavy thunderstorm activity that is not increasing in intensity or areal coverage. The large amount of dry air to the west of 95L is interfering with development. Wind shear over the system was a prohibitively high 30 knots last night, but fell dramatically to just 10 knots this morning, and is expected to remain in the moderate range, 10 - 15 knots, through Sunday. The system should be near Miami on Saturday night, and should then get absorbed by a cold front and turn north towards South Carolina. It is unlikely that 95L has enough time to grow into a tropical depression, given the short amount of time it has over water, and the presence of so much dry air to the west. However, an Air Force Hurricane Hunter aircraft is on call to investigate the system Saturday afternoon, if necessary.

In the Southwest Caribbean, intermittent heavy thunderstorm activity continues off the coast of Nicaragua, in association with a 1007 mb low. This low does have some spin to it, but the associated heavy thunderstorm activity is very limited at present, due to a large amount of dry air to the north. None of the computer models is forecasting tropical cyclone development over the coming seven days.


Figure 1. Afternoon satellite image of Invest 95L.

The road to Copenhagen
By some accounts, the future of the world will be at stake this December, when the crucial U.N. Climate Change Conference will be held December 7 - 18 in Copenhagen, Denmark. At that meeting, the leaders of the world will gather to negotiate an agreement to replace the 1997 Kyoto Protocol. The new agreement will be the world's road map for dealing with climate change, and the stakes are huge. In the coming weeks, major efforts will be made by both sides of the debate to sway public opinion on climate change. Opponents of CO2 emission regulations made their case last weekend, with the release of the video, Not Evil, Just Wrong. Billed as the largest simultaneous film premiere party in U.S. history, the movie aired on 7,000 screens in 50 states. The movie was originally intended to be released at major theaters throughout the U.S., but Hollywood showed insufficient interest in the film. The producers were forced to release the movie on video and hold private "movie parties" for its opening. The movie fiercely attacks Al Gore, and decrys "the true cost of global warming hysteria" on jobs and the economy.

This Sunday, the green lobby is fighting back. The newly-formed climate advocacy group 350.org is sponsoring 4,517 actions in 173 countries. The group is seeking to promote the views of leading climate scientists, including NASA's Dr. James Hansen, that the highest "safe" level of CO2 in the atmosphere is 350 ppm--lower than the current 388 ppm, and far below the target value of 450 ppm typically cited as the "danger" level for atmospheric CO2. The plan is to have thousands of citizens making giant human 3s in some cities, 5s in others, and 0s in others--a sort of planet-scale Scrabble game that they hope CNN and BBC will try to solve for them on the evening news. There will be underwater rallies on the Great Barrier Reef in Australia and in the Middle East off the coast of Oman. Over 300 land-based rallies will be held in China, and 1,000 in the U.S.

With tropical season winding down, I plan to make regular posts over the next six weeks analyzing the scientific claims of efforts by the green lobby and the opponents of CO2 emission regulations to win your hearts and minds in the run-up to the December 7 conference in Copenhagen. My first post in this series will look at 350.org's claim that 350 ppm of CO2 represents the danger level for CO2 in the atmosphere. I'll also look at an audacious TV ad that boldly asserts that more CO2 in the atmosphere is better for Earth's ecosystems.


Figure 2. Competing for your hearts and minds: Cover of the DVD Not Evil, Just Wrong (left), and a promotional image from the http://www.350.org web site (right), showing children in India spelling out the number "350" to promote a 350 ppm target for CO2 levels in the atmosphere.

Next post
I'll have a new post on Saturday.

Hurricane

Updated: 6:32 PM GMT en Agosto 18, 2011

Permalink

Bahamas disturbance 95L could become tropical depression; Lupit spares Philippines

By: JeffMasters, 3:03 PM GMT en Octubre 23, 2009

An area of disturbed weather over the central Bahama Islands associated with a surface trough of low pressure has been designated Invest 95L by NHC this morning, and has the potential to become a tropical depression on Saturday. This morning's QuikSCAT pass showed a large, disorganized circulation in the region, and recent satellite loops show a modest and slowly increasing amount of heavy thunderstorm activity. Wind shear over the system was a prohibitively high 30 knots last night, but has fallen dramatically to just 10 knots this morning, and is expected to remain in the moderate range, 10 -15 knots, through Sunday. There is a large region of dry air to the west of 95L, and this dry air is interfering with development. This system is expected to move west-northwest and be near Miami on Saturday night, then potentially turn northwards towards South Carolina. It is unlikely that 95L has enough time to grow to more than a minimal tropical storm with 45 mph winds. An Air Force Hurricane Hunter aircraft is on call to investigate the system Saturday afternoon, if necessary.


Figure 1. Morning satellite image of Invest 95L.

Typhoon Lupit spares the Philippines
Tropitcal Storm Lupit has weakened and turn northward, out to sea, sparing the storm-ravaged Philippine Island of Luzon from further misery. Lupit never made landfall and the heaviest rains stayed out to sea, with rainfall amounts from the typhoon generally ranging from 1 - 2 inches over northern Luzon Island. Lupit means "cruel" in Tagalog, one of the main languages of the Philippines, but Lupit was primarily cruel in a psychological sense, keeping jittery residents on edge for days as the storm slowly approached. Luzon is still recovering from the destruction wrought by back-to-back typhoons Ketsana and Parma, which killed 860 people and did $642 million in damage.

The road to Copenhagen
By some accounts, the future of the world will be at stake this December, when the crucial U.N. Climate Change Conference will be held December 7 - 18 in Copenhagen, Denmark. At that meeting, the leaders of the world will gather to negotiate an agreement to replace the 1997 Kyoto Protocol. The new agreement will be the world's road map for dealing with climate change, and the stakes are huge. In the coming weeks, major efforts will be made by both sides of the debate to sway public opinion on climate change. Opponents of CO2 emission regulations made their case last weekend, with the release of the video, Not Evil, Just Wrong. Billed as the largest simultaneous film premiere party in U.S. history, the movie aired on 7,000 screens in 50 states. The movie was originally intended to be released at major theaters throughout the U.S., but Hollywood showed insufficient interest in the film. The producers were forced to release the movie on video and hold private "movie parties" for its opening. The movie fiercely attacks Al Gore, and decrys "the true cost of global warming hysteria" on jobs and the economy.

This Sunday, the green lobby is fighting back. The newly-formed climate advocacy group 350.org is sponsoring 4,517 actions in 173 countries. The group is seeking to promote the views of leading climate scientists, including NASA's Dr. James Hansen, that the highest "safe" level of CO2 in the atmosphere is 350 ppm--lower than the current 388 ppm, and far below the target value of 450 ppm typically cited as the "danger" level for atmospheric CO2. The plan is to have thousands of citizens making giant human 3s in some cities, 5s in others, and 0s in others--a sort of planet-scale Scrabble game that they hope CNN and BBC will try to solve for them on the evening news. There will be underwater rallies on the Great Barrier Reef in Australia and in the Middle East off the coast of Oman. Over 300 land-based rallies will be held in China, and 1,000 in the U.S.

With tropical season winding down, I plan to make regular posts over the next six weeks analyzing the scientific claims of efforts by the green lobby and the fossil fuel industry and its allies to win your hearts and minds in the run-up to the December 7 conference in Copenhagen. My first post in this series will look at 350.org's claim that 350 ppm of CO2 represents the danger level for CO2 in the atmosphere. I'll also look at an audacious TV ad that boldly asserts that more CO2 in the atmosphere is better for Earth's ecosystems.


Figure 2. Competing for your hearts and minds: Cover of the DVD Not Evil, Just Wrong (left), and a promotional image from the http://www.350.org web site (right), showing children in India spelling out the number "350" to promote a 350 ppm target for CO2 levels in the atmosphere.

Next post
Well, I must admit to not being on the ball with this one--the sudden development of 95L caught me by surprise. I'll make another post this afternoon if the system shows significant development.

Jeff Masters

Hurricane

Updated: 6:33 PM GMT en Agosto 18, 2011

Permalink

The Atlantic is quiet; Typhoon Lupit spares the Philippines

By: JeffMasters, 1:46 PM GMT en Octubre 23, 2009

There's only good news to report in the tropics today. The tropical disturbance in the Western Caribbean has weakened and shrunk, and has little prospect of developing into a tropical depression for at least the next three days. None of the computer models is forecasting tropical cyclone development in the Atlantic over the next seven days. Hurricane season is not over yet, though, and we will still need to keep a watchful eye on the Western Caribbean. Wind shear is expected to remain low there for most of the next two weeks, according to recent forecast runs of the GFS model. I expect I'll be talking about "Invest 95L" in the Western Caribbean sometime in the next two weeks.

Typhoon Lupit spares the Philippines
Tropitcal Storm Lupit has weakened and turn northward, out to sea, sparing the storm-ravaged Philippine Island of Luzon from further misery. Lupit never made landfall and the heaviest rains stayed out to sea, with rainfall amounts from the typhoon generally ranging from 1 - 2 inches over northern Luzon Island. Lupit means "cruel" in Tagalog, one of the main languages of the Philippines, but Lupit was primarily cruel in a psychological sense, keeping jittery residents on edge for days as the storm slowly approached. Luzon is still recovering from the destruction wrought by back-to-back typhoons Ketsana and Parma, which killed 860 people and did $642 million in damage.

The road to Copenhagen
By some accounts, the future of the world will be at stake this December, when the crucial U.N. Climate Change Conference will be held December 7 - 18 in Copenhagen, Denmark. At that meeting, the leaders of the world will gather to negotiate an agreement to replace the 1997 Kyoto Protocol. The new agreement will be the world's road map for dealing with climate change, and the stakes are huge. In the coming weeks, major efforts will be made by both sides of the debate to sway public opinion on climate change. Opponents of CO2 emission regulations made their case last weekend, with the release of the video, Not Evil, Just Wrong. Billed as the largest simultaneous film premiere party in U.S. history, the movie aired on 7,000 screens in 50 states. The movie was originally intended to be released at major theaters throughout the U.S., but Hollywood showed insufficient interest in the film. The producers were forced to release the movie on video and hold private "movie parties" for its opening. The movie fiercely attacks Al Gore, and decrys "the true cost of global warming hysteria" on jobs and the economy.

This Sunday, the green lobby is fighting back. The newly-formed climate advocacy group 350.org is sponsoring 4,517 actions in 173 countries. The group is seeking to promote the views of leading climate scientists, including NASA's Dr. James Hansen, that the highest "safe" level of CO2 in the atmosphere is 350 ppm--lower than the current 388 ppm, and far below the target value of 450 ppm typically cited as the "danger" level for atmospheric CO2. The plan is to have thousands of citizens making giant human 3s in some cities, 5s in others, and 0s in others--a sort of planet-scale Scrabble game that they hope CNN and BBC will try to solve for them on the evening news. There will be underwater rallies on the Great Barrier Reef in Australia and in the Middle East off the coast of Oman. Over 300 land-based rallies will be held in China, and 1,000 in the U.S.

With tropical season winding down, I plan to make regular posts over the next six weeks analyzing the scientific claims of efforts by the green lobby and the fossil fuel industry and its allies to win your hearts and minds in the run-up to the December 7 conference in Copenhagen. My first post in this series will look at 350.org's claim that 350 ppm of CO2 represents the danger level for CO2 in the atmosphere. I'll also look at an audacious TV ad that boldly asserts that more CO2 in the atmosphere is better for Earth's ecosystems.


Figure 1. Competing for your hearts and minds: Cover of the DVD Not Evil, Just Wrong (left), and a promotional image from the http://www.350.org web site (right), showing children in India spelling out the number "350" to promote a 350 ppm target for CO2 levels in the atmosphere.

Next post
Expect my next post on Monday morning, unless there's some significant development in the tropics.

Jeff Masters

Hurricane

Updated: 6:33 PM GMT en Agosto 18, 2011

Permalink

Western Caribbean disturbance less organized; Typhoon Lupit may spare Philippines

By: JeffMasters, 1:49 PM GMT en Octubre 22, 2009

A broad 1009 mb low pressure area is over the Southwest Caribbean near 12N 83W, off the coast of Nicaragua. This low, in combination with an upper-level trough of low pressure, is generating some disorganized heavy thunderstorm activity over the Western Caribbean and Central America. A second 1008 mb low pressure area is over the Pacific Ocean near the coast of Costa Rica. The two lows appear to be competing with each other, with the result that the organization of the thunderstorm activity over the region is less than yesterday's. Recent satellite loops show little change in the areal coverage or intensity of the thunderstorms this morning. NHC designated this disturbance Invest 94L on Tuesday, but is no longer issuing model products for it. This morning's QuikSCAT pass missed the Western Caribbean, but last night's pass showed no signs of a surface circulation. Wind shear is moderate, about 10 - 20 knots, and there is a deep layer of high moisture over the entire Western Caribbean, so we still need to keep an eye on this disturbance. NHC is giving 94L a low (less than 30% chance) of developing into a tropical depression by Saturday. No models predict development of this system over the next seven days, but I'll continue to give a medium (30 - 50% chance) that a Western Caribbean tropical depression will form sometime in the next ten days.

NHC is also mentioning an area of disturbed weather over the Bahamas, associated with a trough of low pressure in the upper atmosphere. This disturbance is moving slowly westwards towards Florida, and is under very high wind shear of 40 knots. No development is likely due to the high shear.


Figure 1. Morning satellite image of twin surface low pressure systems, on either side of Central America.

Typhoon Lupit may spare the Philippines
Typhoon Lupit continues to struggle with dry air, which has significantly disrupted the typhoon's inner core, leading to a partial collapse of the eyewall. Lupit is now a minimal Category 1 storm with 75 mph winds. Recent microwave imagery shows that the typhoon is missing a large portion of its western eyewall, and this morning's infrared satellite loop shows that the storm's heavy thunderstorm activity is rather disorganized. Even in its current weakened state, Lupit is a dangerous rain-maker, with rainfall rates exceeding twelve inches per day near its core (Figure 2).

While it is too early to be confident of this forecast, it now appears that Lupit will spare the Philippines a direct hit and a punishing deluge of 12+ inches of rain. The typhoon has slowed in reaction to a collapse of the steering currents, and most of the models are now calling for Lupit to stall just offshore, or recurve to the northeast. The very slow motion of the storm means that it will stir up large quantities of cool water from the depths that will then surround the storm, making re-intensification unlikely, and decreasing the amount of rain the storm is able to produce. The typhoon's core of heaviest rain appears likely to remain offshore, though the extreme northern portion of Luzon Island may still receive 6 - 12 inches of rain before the storm finally departs.

Storm chaser Jim Edds is in northern Luzon to document Lupit's impact, and has photos of the preparations the residents are taking.


Figure 2. Forecast rainfall for the 24-hour period ending at 06 UTC Friday 10/23/09. Lupit is expected to dump rains in excess of twelve inches (red colors) near its core. However, this core of heavy rain will remain offshore over at least the next two days. Image credit: NOAA/NESDIS.

I'll have an update Friday morning.

Jeff Masters

Hurricane

Updated: 6:33 PM GMT en Agosto 18, 2011

Permalink

Western Caribbean disturabance 94L bringing heavy rains; Lupit's path uncertain

By: JeffMasters, 2:39 PM GMT en Octubre 21, 2009

A broad 1008 mb low pressure area has developed near 10N 84W, inland over Costa Rica. NHC designated this disturbance Invest 94L yesterday, but is no longer issuing model products for the disturbance. This morning's QuikSCAT pass showed a broad circulation around the low, with top winds of about 30 - 35 mph over the extreme Southwestern Caribbean. Obviously, the center will have to move over water in order for significant development to occur, but recent satellite loops show that the low is pulling in an increasing amount of moisture from the Pacific, leading to heavy rains over Costa Rica and western Panama. Wind shear is low, about 5 - 10 knots, and there is deep layer of high moisture over the entire Western Caribbean, which both favor development if the center moves over water. Rainfall estimates from the Navy Research Lab indicate that 94L dumped up to three inches of rain over portions of Panama, Costa Rica, and Nicaragua over the past 24 hours.


Figure 1. Morning satellite image of Invest 94L.

The forecast for 94L
Wind shear is expected to remain in the low to moderate range, 5 - 15 knots, for the next five days in the Western Caribbean. Sea Surface temperatures are very warm, 29°C, and there is plenty of moisture through a deep layer of the atmosphere. The only major impediment to 94L becoming a tropical storm later this week would seem to be proximity to land. At present, only the GFS model develops 94L, but weeks it very weak. The GFS predicts the storm will take a north then northwesterly track across western Cuba early next week, then into the Gulf Coast of Florida later in the week. However, it is equally likely that 94L will stay bottled up in the Western Caribbean for the foreseeable future. I'll continue to give 94L a medium (30 - 50% chance) of eventually becoming a tropical depression over the next ten days. NHC is giving 94L a low (less than 30% chance) of developing into a tropical depression by Friday, which is a good forecast. Given 94L's current state of disorganization and location over land, Saturday is the earliest we should expect it to organize into a tropical depression. NHC has not put the Hurricane Hunters on call to fly 94L Thursday or Friday.

Rick misses Baja, hits Mainland Mexico near Mazatlan
Tropical Storm Rick made landfall near 10am EDT in Mainland Mexico just north of Mazatlan. Top winds measured at the Matatlan airport during landfall were 39 mph, gusting to 61 mph. The primary threat from Rick will be heavy rains of up to six inches in the mountains near Mazatlan. Rick's remains should being at most one inch of rain to south-central Texas on Thursday.

Typhoon Lupit weakens and slows; path now uncertain
Typhoon Lupit, now a Category 1 storm with 90 mph winds, continues to have difficulty dealing with a slug of dry air it wrapped into its core two days ago. Microwave imagery showed that the typhoon was missing a portion of its northern eyewall this morning. However, recent Infrared satellite loops show that the eye has warmed and become more distinct, a sign of intensification. Also, the cloud tops of Lupit's eyewall have cooled in recent hours, signaling that they are more vigorous and reaching higher into the atmosphere. Lupit is in an environment favorable for re-intensification, with low wind shear of 5 - 10 knots and warm sea surface temperatures of 28 - 29°C. It would not be a surprise to see Lupit intensify into a major Category 3 typhoon again by Thursday, though the official forecast from the Joint Typhoon Warning Center is less aggressive, calling for a Category 2 storm by tomorrow. Even in its current weakened state, Lupit is a prodigious rain-maker, with rainfall rates exceeding one inch per hour near its core (Figure 2).

The future path of the typhoon is now highly uncertain, as steering currents are weakening and the storm is slowing down. A weakness in the ridge of high pressure steering Lupit west-southwest is developing, and several models (ECMWF, GFS) now predict recurvature of the typhoon before it reaches the Philippines. This optimistic scenario is counterbalanced by the very pessimistic forecasts of the UKMET and NOGAPS models, which take the typhoon inland over the northern portion of Luzon 1 - 2 days from now, and then stall the storm for 2 - 3 days. This would cause a major flooding disaster, as the soils are already saturated and the dams completely full from the 20+ inches of rain dumped by Super Typhoon Parma in early October. If Lupit stalls for several days over Luzon, it would dump another 20+ inches of rain, triggering massive flash flooding and life-threatening mudslides.

Storm chased Jim Edds is in northern Luzon to document Lupit's landfall, and has some interesting photos of the preparations the residents are taking.


Figure 2. Rainfall rates observed by a polar-orbiting microwave satellite at at 10:24 UTC Wednesday 10/21/09. Lupit is expected to dump rains in excess of one inch per hour (red and pink colors) along its path. Up to 12 inches of rain in a 24-hour period are expected from the typhoon. Image credit: Navy Research Lab, Monterey..

I'll have an update Thursday morning.

Jeff Masters

Hurricane

Updated: 6:33 PM GMT en Agosto 18, 2011

Permalink

Western Caribbean disturbance 94L organizing; Rick wanes; Lupit still dangerous

By: JeffMasters, 1:59 PM GMT en Octubre 20, 2009

A broad 1010 mb low pressure area has developed near 13N 81W in the Western Caribbean, about 300 miles east of the Nicaraguan coast. NHC designated this disturbance Invest 94L this morning. This morning's QuikSCAT pass showed no evidence of a surface circulation, and not even much of a shift in wind direction associated with the low. Wind shear is moderate, about 10 - 20 knots, and there is deep layer of high moisture over the entire Western Caribbean, which will aid development. The heavy thunderstorm activity associated with 94L has not increased in intensity or areal coverage much over the past 24 hours, but it has begun getting more organized, with some curved bands beginning to form, indicating that a circulation at middle levels of the atmosphere may be starting to spin up. The disturbance will bring 3-day rain totals of 4 - 8 inches to eastern Nicaragua and northeastern Honduras through Thursday, as 94L moves slowly northwestward. As the storm organizes, it may begin to pull moisture from the Pacific across Costa Rica, Panama, and Nicaragua, resulting in flooding rains of 4 - 8 inches along the Pacific slopes of those countries Wednesday through Friday.


Figure 1. Current satellite image of Invest 94L.

The forecast for 94L
The SHIPS model forecasts that wind shear will remain in the moderate range, 10 - 15 knots, for the next five days in the Western Caribbean. Sea Surface temperatures are very warm, 29°C, and there is plenty of moisture through a deep layer of the atmosphere. The only major impediment to 94L becoming a tropical storm later this week would seem to be proximity to land. Most of the models foresee a path taking 94L very close to the coast of Nicaragua and then along the north coast of Honduras, and the storm may move inland over one of these countries before it has time to develop into a tropical depression. Due to proximity to land, I give 94L just a medium (30 - 50% chance) of becoming a tropical depression over the next ten days. NHC is giving 94L a low (less than 30% chance) of developing into a tropical depression by Thursday, which is a good forecast. Given 94L's current state of disorganization, Friday is the earliest we should expect it to organize into a tropical depression. NHC has not put the Hurricane Hunters on call to fly 94L Wednesday or Thursday. The ECMWF model foresees that 94L will move northwards next week across Cuba and threaten South Florida, but none of the other models are predicting this. It is too early to know if 94L will be a threat to more than just Central America.

Rick wanes
Tropical Storm Rick has faded from its glory as the second strongest Eastern Pacific hurricane of all time to a mere tropical storm, thank to continued moderate to high wind shear of 15 - 25 knots over the past 36 hours. The shear has managed to inject dry air that lies to the west of Rick directly into its core, which significantly disrupted the storm. With the shear expected to continue at 15 - 25 knots between now and landfall in mainland Mexico on Wednesday afternoon, it is unlikely that the storm will be able to take advantage of the warmer sea surface temperatures it will find along its path over the next 24 hours and re-intensify. It looks like the southern tip of Baja will miss the more severe right-front quadrant of the storm, and NHC is currently giving both Cabo San Lucas and San Jose Cabo on Baja's southern tip just a 50% chance of receiving tropical-storm force winds of 39 mph or greater. The main threat from Rick will be heavy rains over the mountains of Mexico when Rick penetrates inland on Wednesday evening. South Texas can expect just 1 - 2 inches of rain from Rick's remains on Thursday and Friday.

Typhoon Lupit weakens, but still dangerous for the Philippines
Typhoon Lupit has weakened to a Category 2 storm with 95 mph winds, thanks to some dry air that wrapped into the typhoon's core over the past 24 hours, which disrupted the eyewall. It appears from satellite and microwave imagery that Lupit's eyewall is attempting to re-form now, as no more dry air is being sucked into the storm. Lupit is headed west towards a landfall Thursday on the northern portion of Luzon Island in the Philippines. Wind shear over Lupit is in the low range, 5 - 10 knots, and the typhoon is embedded in a very moist environment with warm sea surface temperatures of 28 - 29°C. Total heat content of the ocean will increase sharply in the final 12 hours before landfall, and it would not be a surprise to see Lupit re-intensify into a major Category 3 storm before landfall.

The northern Philippines are still reeling from the rains and mudslides unleashed by Super Typhoon Parma last week, which crossed over the northern Philippines three times, dumping over twenty inches of rain in many locations. Parma killed 438 people, and 51 are still missing. A week prior to Parma, Typhoon Ketsana brought the heaviest rains in 42 years to the capital of Manila, killing 420 people, with 37 still missing. Lupit will move relatively quickly over the Philippines, but the typhoon is likely to dump 12+ inches of rain over the already saturated soils of northern Luzon Island. These rains will create life-threatening flash floods and mudslides capable of killing hundreds more Filipinos.


Figure 2. Rainfall forecast for Typhoon Lupit for the 24-hour period ending at 06 UTC Wednesday 10/21/09. Lupit is expected to dump rains in excess of 12 inches (red colors) in a small region near its center. Image credit: NOAA/NESDIS.

Cool video
NOAA's Environmental Visualization Laboratory has put together a 4-minute Flash video of the 2008 hurricane season. Infrared satellite imagery for each hour of each day during the 6-month season is looped, and it is fascinating to watch the daily build-up of thunderstorms progress from east to west across the country as each day waxes and wanes. Note that as we head into September this thunderstorm activity diminishes as the continent cools.

I'll have an update Wednesday morning.

Jeff Masters

Hurricane

Updated: 6:33 PM GMT en Agosto 18, 2011

Permalink

Rick weakens; Lupit headed to the Philippines; Western Caribbean brewing a storm?

By: JeffMasters, 2:09 PM GMT en Octubre 19, 2009

Hurricane Rick has weakened significantly over the past 24 hours, thanks to moderate wind shear of 15 - 20 knots. Although still a powerful Category 3 hurricane with 125 mph winds, this is a far cry from the spectacular Category 5 hurricane with 180 mph winds and 905 mb pressure Rick was early Sunday morning. At that time, Rick was the second most powerful hurricane ever recorded in the Eastern Pacific. The only Eastern Pacific hurricane that was stronger was Hurricane Linda of 1997, which had 185 mph winds and a 902 mb pressure. Reliable satellite measurements of Eastern Pacific storms go back to about 1970, and Rick is the 11th Category 5 hurricane in the Eastern Pacific since 1970.


Figure 1.Hurricane Rick just after peak intensity at 17:55 UTC October 18, 2009. A this time, Rick was a Category 5 hurricane with 175 mph winds. Image credit: NASA.

Recent microwave satellite imagery suggests that wind shear may have eaten away the southwest portion of Rick's eyewall, allowing dry air to intrude into the core of the storm. The Hurricane Hunters will visit Rick this afternoon to learn more, and I suspect Rick is weaker than the Category 3 hurricane with 125 mph winds that is currently advertised.

Wind shear will increase to the high range, 20 - 30 knots, in the 24 hours before landfall, and ocean heat content and sea surface temperatures will steadily decrease over the next two days as Rick approaches Baja. The latest GFDL and HWRF model runs put Rick at Category 1 strength at its closest approach to Baja, and this appears to be a reasonable forecast given the current appearance of Rick. NHC is currently giving both Cabo San Lucas and San Jose Cabo on Baja's southern tip a 20% chance of receiving hurricane-force winds from Rick. Rick will make a second landfall in Mainland Mexico on Wednesday night, and the moisture from Rick should reach southern Texas by Friday, possibly leading to heavy rains there on Friday and Saturday.

Typhoon Lupit a potential major disaster for the Philippines
Category 4 Super Typhoon Lupit has begun its turn to the west over the Philippine Sea, and is headed towards a landfall early Thursday morning on the northern portion of Luzon Island in the Philippines. Thanks to the departure of a trough of low pressure that was pulling the super typhoon to the northeast and creating a region of weak steering currents, a strong ridge of high pressure is now building in over Lupit and will force it slightly south of due west. The models are all in excellent agreement on the forecast track taking the super typhoon over northern Luzon as a major Category 3 or 4 typhoon, and Lupit--the Filipino word for cruel--is very likely to live up to its name. The northern Philippines are still reeling from the rains and mudslides unleashed by Super Typhoon Parma last week, which crossed over the northern Philippines three times, dumping over twenty inches of rain in many locations. Parma killed 438 people, and 51 are still missing. A week prior to Parma, Typhoon Ketsana brought the heaviest rains in 42 years to the capital of Manila, killing 420 people, with 37 still missing.


Figure 2. Rainfall forecast for Super Typhoon Lupit for the 24-hour period ending at 06 UTC Tuesday 10/20/09. Lupit is expected to dump 8 - 12 inches of rain (orange colors) in a small region near its center. Image credit: NOAA/NESDIS.

Wind shear over Lupit is in the low range, 5 - 10 knots, and the typhoon is embedded in a very moist environment with warm sea surface temperatures of 28 - 29°C. Total heat content of the ocean is too low (20 kJ/cm^2) to permit much additional intensification over the next two days, but in the final 12 hours before landfall, the total oceanic heat content will rise to 80 kJ/cm^2, which should allow Lupit to retain at least Category 3 strength right up until landfall, despite interaction of the storm with land. Lupit will move relatively quickly over the Philippines, but the typhoon is likely to dump 12+ inches of rain over the already saturated soils of northern Luzon Island. These rains will create life-threatening flash floods and mudslides capable of killing hundreds more Filipinos.


Figure 3 Morning visible satellite image of the area of disturbed weather in the Western Caribbean.

A Western Caribbean tropical storm coming?
In the Atlantic, an area of disturbed weather has developed in the Western Caribbean from Costa Rica to the Cayman Islands, in association with the remains of a cold front, a tropical wave, and a broad 1010 mb low pressure region that has developed over the extreme southwestern Caribbean off the coast of Costa Rica. Last night's QuikSCAT pass showed that the low off the coast of Costa Rica had a broad and disorganized surface circulation. The thunderstorm activity associated with this large and complicated area of disturbed weather is disorganized and under 10 - 30 knots of wind shear, and any development over the next three days will be slow. However, by Friday, wind shear over the Western Caribbean is expected to drop significantly, and development of a tropical depression in the Western Caribbean becomes a more real possibility. Numerous runs over the past few days of all of our reliable global forecast models have shown a tropical depression developing in the Western Caribbean by early next week. The timing, location, and track of such a such a storm are all pretty hazy, but I think there is a 60% chance of a named storm forming in the Western Caribbean sometime in the next 10 days. The regions most likely to be affected by such a storm would be Honduras, Nicaragua, and the Cayman Islands, and it is possible that such a storm may stay trapped in the Western Caribbean for many days (as predicted by the GFS model). Alternatively, the storm could move steadily northwards after formation, affecting western Cuba, the Cayman Islands, Jamaica, South Florida, and the Bahamas. This is the solution preferred by the ECMWF model. In either case, a long period of disturbed weather is likely for the Western Caribbean. Heavy rains will affect northeast Honduras, eastern Nicaragua, and the Cayman Islands this week, and could spread to adjacent countries as the area of disturbed weather evolves.

Jeff Masters

Hurricane

Updated: 6:35 PM GMT en Agosto 18, 2011

Permalink

Super Hurricane Rick the 2nd strongest hurricane ever recorded in Eastern Pacific

By: JeffMasters, 3:27 PM GMT en Octubre 18, 2009

Hurricane Rick intensified in dramatic fashion yesterday into the second most powerful hurricane ever recorded in the Eastern Pacific. Truly deserving of the title "Super Hurricane", Rick grew into a monstrous Category 5 storm with 180 mph winds and a central pressure of 906 mb early this morning. The only Eastern Pacific hurricane that was stronger was Hurricane Linda of 1997, which had 185 mph winds and a 902 mb pressure. Reliable satellite measurements of Eastern Pacific storms go back to about 1970, and Rick is the 11th Category 5 hurricane in the Eastern Pacific since 1970. Meteorologists like to talk about a hurricane's Maximum Potential Intensity (MPI), the theoretical upper limit of a hurricane's intensification given the prevailing ocean heat content and atmospheric stability and moisture. Less than 5% of all hurricane reach their MPI, due to wind shear, interaction with land, entrainment of dry air, or other factors. Hurricane Rick was able to take advantage of nearly ideal conditions for intensification--light wind shear, high ocean heat content, and plenty of mid-level atmospheric moisture--to reach its MPI and intensify into one of the strongest and most spectacular tropical cyclones ever recorded. The last tropical cyclone to attain Rick's intensity was Australia's Cyclone Monica of 2006, which also had 180 mph winds. Only nine Atlantic hurricanes in recorded history have been stronger than Rick.


Figure 1.Hurricane Rick at peak intensity on Sunday morning, October 18, 2009: 180 mph winds and a central pressure of 905 mb.

Wind shear will gradually increase and ocean heat content decrease over the next few days as Rick approaches Baja, and the hurricane should weaken considerably before landfall on Wednesday. The latest GFDL model run puts Rick at Category 2 strength, but Rick could still be a major Category 3 hurricane at landfall, as predicted by the HWRF model. More rapid weakening into a Category 1 hurricane is also a distinct possibility, and the official NHC intensity forecast of a Category 2 forecast at landfall is a good middle-of-the-road forecast. Rick will make a second landfall in Mainland Mexico on Thursday, and the moisture from Rick should reach southern Texas by Saturday, possibly leading to heavy rains there next weekend.

Typhoon Lupit a potential major catastrophe for the Philippines
Category 4 Super Typhoon Lupit is stalled out over the Philippine Sea east of northern Luzon Island in the Philippines, but is expected to resume a westerly track towards the Philippines on Monday. Depending upon whether the storm makes landfall in northern Luzon or not, Lupit (the Filipino word for cruel) has the potential to live up to its name if it makes landfall as a major typhoon on Thursday, as currently forecast. A week ago, Super Typhoon Parma crossed over the northern Philippines three times, dumping over twenty inches of rain in many locations. Over 300 people died in the resulting flash floods and landslides. A visit by Typhoon Lupit would bring another 12+ inches of rain to the already-soaked soils of the region, creating a major catastrophe. However, there is hope that storm's current slow and erratic movement will carry Lupit far enough north that the typhoon will miss the Philippines.

Early snow in Northeast U.S. sets records
This weekend's snowstorm in the Northeast set records for the earliest date with an inch of snow in Binghamton, Ithaca and Olean in New York and Altoona and State College in Pennsylvania. State College received 4.8 inches of snow from the storm, and snow amounts as high as ten inches were recorded in the surrounding mountains.

A Western Caribbean tropical storm coming?
In the Atlantic, there have been some modest flare-ups of heavy thunderstorm clusters in the extreme Southwest Caribbean off the coasts of Nicaragua and Panama over the past day. This activity has been too disorganized and limited in extent to prove a threat to develop. However, for the past three days, the ECMWF model has been predicting the eventual development of a tropical storm in this region, sometime during the period October 23 - 25. The GFS and NOGAPS models have also been hinting that conditions may become favorable for tropical storm formation in the Western Caribbean early next week, and we should anticipate the possibility of a late-season tropical storm forming. The regions most likely to be affected by such a storm would be Honduras, Nicaragua, western Cuba, the Cayman Islands, Jamaica, Mexico's Yucatan Peninsula, South Florida, and the Bahamas. Stay tuned.

Jeff Masters

Hurricane

Updated: 6:35 PM GMT en Agosto 18, 2011

Permalink

Second warmest September on record for the globe

By: JeffMasters, 12:49 PM GMT en Octubre 16, 2009

The globe recorded its second warmest September since record keeping began in 1880, according to NOAA's National Climatic Data Center. The combined global land and ocean temperature anomaly was 0.62°C (1.12°F), falling only 0.04°C (0.07°F) short of tying the record set in 2005. NASA's Goddard Institute for Space Studies also rated September 2009 as the 2nd warmest September on record, falling 0.02°C short of the record set in 2005. It was the 33rd consecutive September with a global temperature above the 20th century average. NOAA rated the year-to-date period, January - September 2009, as the sixth warmest such period on record. The September satellite-measured temperatures for the lowest 8 km of the atmosphere were the 2nd warmest on record, behind 1998. Global ocean Sea Surface Temperature (SST) anomalies, however, cooled a bit, and were the 5th warmest on record. Global SSTs were the warmest on record during the Northern Hemisphere summer, June - August.


Figure 1. Departure of temperature from average for September 2009. Image credit: National Climatic Data Center.

A warm September for the U.S., and record heat in the West
For the contiguous U.S., the average September temperature was 1.0°F above average, making it the 32nd warmest September in the 115-year record, according to the National Climatic Data Center. The West had is warmest September on record, with Nevada and California recording their warmest September, and six other western states observing a top-ten warmest September--Montana (3rd warmest), North Dakota (3rd), Idaho (4th), Utah (5th), Minnesota (6th), and Oregon (8th). However, a combination a slow-moving storm system during the beginning of the month and two surface cold fronts during the last week resulted in much below normal temperature averages in Kansas (10th coolest) and Oklahoma (11th coolest). The year-to-date (January - September) period was the 29th warmest such period for the contiguous U.S.

U.S. precipitation near average
U.S. precipitation in September was exactly average. Statewide-averaged rainfall was among the ten wettest for four southern states (Arkansas, 2nd wettest; Tennessee (5th), Mississippi (6th), and Alabama (6th)). Maine and Wisconsin each experienced their fourth driest September and both New Hampshire and Michigan had their seventh driest such periods.

U.S. drought
At the end of September, 15% of the contiguous United States was in moderate-to-exceptional drought. This is a drop from the 19% figure observed at the beginning of the year. Exceptional drought (the worst category of drought) was seen in South to Central Texas, though the area covered by exceptional drought shrank by 50% over the past month, thanks to much-needed rains over the region.

U.S. fire activity
During September, 5,535 fires burned approximately 378,523 acres, each of which was below the 2000 - 2009 average for the month. The acreage lost to wildfire was roughly half of the 2000 - 2009 average. For the year to date (January.September), 70,217 fires was slightly above the 10-year average, while acreage burned was slightly less than average.

Weak El Niño conditions continue
El Niño conditions continue over the tropical Eastern Pacific. Ocean temperatures in the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region", were 0.3°C above the threshold for a weak El Niño, according to the Australian Bureau of Meteorology. NOAA's Climate Prediction Center is maintaining an El Niño Advisory. Current conditions and model forecasts favor the continued development of a weak-to-moderate strength El Niño event into the Northern Hemisphere Fall 2009, with the likelihood of at least a moderate strength El Niño (3-month Niño-3.4 SST index of +1.0°C or greater) during the Northern Hemisphere Winter 2009-10.

September sea ice extent in the Arctic 3rd lowest on record
September 2009 Northern Hemisphere sea ice extent was the 3rd lowest since satellite measurements began in 1979, according to the National Snow and Ice Data Center (NSIDC). Only 2007 and 2008 saw lower Arctic sea ice extent. Both the Northwest Passage and Northeast Passage melted free, according to the National Snow and Ice Data Center. This marks the second consecutive year--and the second time in recorded history--both of these Arctic shipping routes have melted free. The past five years have had the five lowest Arctic ice extents on record. In their 2009 report on this year's Arctic sea ice minimum, NSIDC Director and Senior Scientist Mark Serreze said, "It's nice to see a little recovery over the past couple years, but there's no reason to think that we're headed back to conditions seen back in the 1970s. We still expect to see ice-free summers sometime in the next few decades". Only 19% of the ice cover this summer in the Arctic was over 2 years old, the least in the satellite record, and far below the 1981 - 2000 average of 52%. NSIDC Scientist Walt Meier said, "We've preserved a fair amount of first-year ice and second-year ice after this summer compared to the past couple of years. If this ice remains in the Arctic through the winter, it will thicken, which gives some hope of stabilizing the ice cover over the next few years. However, the ice is still much younger and thinner than it was in the 1980s, leaving it vulnerable to melt during the summer". Earlier this summer, NASA researcher Ron Kwok and colleagues from the University of Washington in Seattle published satellite data showing that Arctic ice thickness declined by 0.68 meters (2.2 feet) between 2004 and 2008. The overall mean winter thickness was 3.64 meters in 1980, and 1.89 meters during the winter of 2007 - 2008, a massive decrease of 48%.

References
Kwok, R., and D. A. Rothrock. 2009. Decline in Arctic sea ice thickness from submarine and ICESat records: 1958.2008, Geophys. Res. Lett., 36, L15501, doi:10.1029/2009GL039035.


Figure 2. Category 1 Typhoon Lupit in the Philippine Sea at 04:45 UTC October 16, 2009. Image credit: NASA MODIS Rapid Response System.

Tropical update
In the Atlantic, there are no threat areas to discuss, and none of the computer models is calling for tropical storm formation over the next week.

There are two potential serious threats in the Pacific. Tropical Storm Rick off the Pacific coast of Mexico is expected to recurve to the north and threaten Baja late next week. While Rick is expected to become a major hurricane early next week, the storm should weaken significantly before any potential landfall in Mexico, due to high wind shear and cooler ocean temperatures the storm will find as it approaches Baja.

More seriously, Typhoon Lupit in the Western Pacific is expected to intensify into a Category 4 typhoon and threaten the northern Philippines by Tuesday. Last week, Super Typhoon Parma crossed over the northern Philippines three times, dumping over twenty inches of rain in many locations. Over 300 people died in the resulting flash floods and landslides. A visit by Typhoon Lupit could create a major catastrophe in the northern Philippines as the storm dumps another 1 - 2 feet of rain on the already saturated soils.

My next post will be Sunday or Monday.

Jeff Masters

Climate Summaries

Updated: 10:23 PM GMT en Octubre 21, 2011

Permalink

Outlook for the remainder of hurricane season

By: JeffMasters, 1:18 PM GMT en Octubre 15, 2009

Atlantic tropical cyclone activity finishes its peak phase in mid-October, and takes a major downturn after about October 20 (Figure 1). Since the current active hurricane period began in 1995, the last half of October through the end of hurricane season has given birth to an average of 1.7 named storms, 0.8 hurricanes, and 0.3 intense hurricanes. These numbers are nearly double the long-term climatological averages for the past 100 years. So far this year, only one tropical storm has hit the U.S.--Tropical Storm Claudette. If no more tropical storms make landfall in the U.S., it will be the first year since 1993 to see only one tropical storm hitting the U.S.


Figure 1. Atlantic hurricane season activity over the past 100 years.

Late October and November storms tend to form from tropical waves that come off the coast of Africa, or from the remains of old fronts that push off the coast of the U.S. As we can see from the track plot of all last half of October storms (Figure 2), there is a lot of activity during the period, but relatively few storms form out near the African coast. The water temperatures off the coast of Africa are starting to cool and be marginal for hurricane formation, and the African Monsoon is waning, leading to fewer African waves coming off the coast. Wind shear is also starting to increase, as part of its normal fall cycle.

Climatology of late-season major hurricanes
Let's examine the possibilities of getting a late-season major hurricane, since those are the storms we care most about. Since 1960, there have been twelve hurricanes that have existed as major Category 3 or higher storms after October 15. Eight of these have occurred since 1995: Omar of 2008 (Cat 4, Lesser Antilles), Paloma of 2008 (Cat 4, Cayman Islands and Cuba), Wilma of 2005 (Cat 4, Mexico; Cat 3, SW Florida), Beta of 2005 (Cat 3, Nicaragua), Michelle of 2001 (Cat 4, Cuba), Lenny of 1999 (Cat 4, northern Lesser Antilles), Mitch of 1998 (Cat 5, Honduras), and Lili of 1996 (Bahamas, Category 3). The other four were Joan of 1988 (Cat 4, Nicaragua), Kate of 1985 (Cat 3, Gulf of Mexico), Ella of 1962 (Cat 3, west of Bermuda), and Hattie of 1961 (Cat 4, Belize). Wilma of 2005 was the only major hurricane since 1960 to hit the U.S. after October 15. The highest risk region for late season major hurricanes is the Western Caribbean, along the coasts of Nicaragua, Honduras, Belize, Mexico, and Cuba. So, we can say with high confidence that most of the U.S. coast can relax. Only the west coast of Florida, Florida Keys, and South Florida need to still be concerned about the possibility of a major hurricane. The Lesser Antilles Islands, Puerto Rico, and Hispaniola are also at low risk for a major hurricane the remainder of the season.



Figure 2. Tracks of all tropical storms and hurricanes since 1851 that formed October 16-31.

Sea Surface Temperatures
Sea Surface Temperatures (SSTs) are 0.5 - 1.5°C above average over the Western Caribbean and Gulf of Mexico (Figure 3), the primary formation areas for late October storms. So, there is still plenty of fuel for a major hurricane to form. Note also the tongue of warmer than average SSTs extending out into the Pacific Ocean from the coast of South America, the signature of weak El Niño conditions.


Figure 3. Sea Surface Temperature (SST) departure from average for October 15. Image credit: NOAA.

Wind shear
Wind shear is usually defined as the difference in wind between 200 mb (roughly 40,000 foot altitude) and 850 mb (roughly 5,000 foot altitude). In most circumstances, wind shear above 20 knots will act to inhibit tropical storm formation by tearing a storm apart. Wind shear 10 knots and lower is very conducive for tropical storm formation.

The jet stream in mid-October is more active and extends further south, which brings higher levels of wind shear to the Atlantic. The more active jet stream also acts to recurve storms more quickly. Any system penetrating north of about 20 degrees north latitude we can expect to recurve quickly to the north and northeast this late in the season. The most recent 16-day forecast from the GFS model predicts a period of high wind shear over the tropical Atlantic over the next ten days (Figure 4). Beginning on October 25, wind shear is expected to fall again over the Western Caribbean, and we need to be alert for tropical storm formation then. Indeed, the latest run of the GFS model is predicting a large area of surface low pressure will form in the Western Caribbean during the last week of October, an indication that hurricane season may not be over yet.

El Niño
El Niño conditions, which typically bring higher wind shear to the Atlantic and interfere with hurricane formation, continue to be present in the tropical Eastern Pacific. It is probably the case that some of this year's inactivity can be attributed to El Niño. However, as I discussed in a post earlier this year, El Niño events that warm the central Pacific more than the eastern Pacific (called "modiki" El Niño events), tend to bring less wind shear to the Atlantic. In recent weeks, El Niño conditions in the Eastern Pacific have trended more towards a "modiki" type event, with a large amount of warming in the Central Pacific. This shift in the El Niño may bring lower wind shear to the Atlantic over the final month of hurricane season.


Figure 4. Wind shear forecast for October 23, 2009, as produced by the 00 UTC run on October 14, 2009 made by the GFS model. Wind shear below about 8 m/s (roughly 15 knots, red colors) is typically needed to allow tropical storm formation. There aren't too many red-colored areas over the prime breeding grounds for tropical storms in the Atlantic over the next ten days in this forecast.

Summary
Given how quiet the tropics are at present, and the forecast of a high wind shear regime lasting until October 25, I doubt any tropical storms will form over the next ten days. If we do get something, it would probably be in the middle Atlantic between Bermuda and the Azores, far from land. However, I am still wary of the possibility of a hurricane in the Caribbean the last week of October or in November this year. There is evidence that the Atlantic hurricane season is starting earlier and ending later in recent decades. Dr. Jim Kossin of the University of Wisconsin published a paper in 2008 titled, "Is the North Atlantic hurricane season getting longer?" He concluded that yes, there is a "apparent tendency toward more common early- and late-season storms that correlates with warming Sea Surface Temperature but the uncertainty in these relationships is high". We had two major hurricanes in the Caribbean after October 15 last year, and I give a 60% chance that we'll get a named storm in the Caribbean before hurricane season ends on November 30. Hurricane season is not over--it's just in hibernation.

Happy Valley to become Yucky Valley
Winter is fast approaching, and the season's first major snowstorm for the U.S. East Coast is coming this weekend, according to the wunderblog of Wunderground's Dr. Rob Carver. Conditions will be particularly nasty on Saturday in Happy Valley, where Penn State is situated. The surrounding hills may get 4 - 12 inches of snow, and rain mixed with snow with 36°F temperatures are expected for Saturday's Penn State - Minnesota game. Ugh, winter! I'll have a forecast for the coming winter in a post sometime in the next week.

The Senate has not yet voted on the proposal to cut NOAA funding. I will post a report when the vote occurs.

Jeff Masters

Hurricane

Updated: 6:35 PM GMT en Agosto 18, 2011

Permalink

Thirsty California soaks up Melor's Deluge

By: JeffMasters, 12:44 PM GMT en Octubre 14, 2009

The remains of Super Typhoon Melor dumped record-breaking amounts of rain over California over the past 24 hours, but the storm is now departing the state without having caused major damage. Mining Ridge in Monterey County had an extraordinary 21.34" of rain, and several locations in Santa Cruz, Monterey, and Santa Clara counties had over 10" of precipitation. Downtown San Francisco recorded 2.49 inches of rain, which is the greatest 24 hour rainfall for the month of October (records have been kept since 1849). Monterey also set a record for the greatest October rainfall, 2.66". Strong winds accompanied the storm, with the Twin Peaks in San Francisco recording a hurricane-force gust of 75 mph, Angel Island, 77 mph, and Los Gatos in the Santa Cruz Mountains, 87 mph. Sustained winds in excess of tropical storm force were experienced at several locations along the coast. The Point Reyes Lighthouse experienced sustained winds of 46 mph, gusting to 63 mph, at the peak of the storm. The Sierra Mountains probably experienced hurricane-force wind gusts, and received several feet of snow. California was lucky this storm came early in their rainy season, since the ground was dry from a year-long drought and the soils were able to absorb a great deal of the rain. Melor's Deluge in California will be a great boon for the state, helping it to overcome one of the most severe droughts in the past 50 years.


Figure 1. Radar-estimated precipitation for Melor's Deluge.

Tropical Storm Patricia dies
Tropical Storm Patricia is no more. The storm died out as it approached Mexico's Baja Peninsula, and caused no major flooding or wind damage.

Quiet in the Atlantic
There are no threat areas in the Atlantic to discuss, and none of the computer models are calling for tropical storm formation over the next seven days.

Listen live at 10:10 am EDT to my Hurricane Hugo lecture
I'm subbing today for Professor Perry Samson's Extreme Weather course at the University of Michigan. He's set up a system where one can listen to the lecture and see the slides of the presenter live (though not the pretty faces). Between 10:10 - 11:00 am EDT today, I'll be presenting a talk, "Hurricane Hugo: the Hurricane Hunters' wildest ride" to the Extreme Weather class, and you're all welcome to tune in. Simply point your browser to http://samson.lecturetools.org and click the "Low Speed Video Stream" button. There is also a "high speed" button, but I'm not sure the network will be able to bear the load if there are a lot of folks tuning in. The lecture will also be recorded for those wanting to view it later.

I haven't heard yet how yesterday's Senate vote on NOAA funding went, the Senate web site indicates that they are still not done debating the bill.

I'll post my rest-of-hurricane-season outlook on Thursday.

Jeff Masters

Hurricane

Updated: 6:35 PM GMT en Agosto 18, 2011

Permalink

Typhoon Melor's remnants pound California; Tropical Storm Patricia nears Baja

By: JeffMasters, 1:27 PM GMT en Octubre 13, 2009

The remains of Super Typhoon Melor, which hit Japan last week, have arrived in Northern California. Tropical storm force winds of 44 mph, gusting to 58 mph, were recorded at 6 am PDT at the Point Reyes Lighthouse north of San Francisco, and tropical storm-force winds have been recorded at several other locations off the Northern California coast. Heavy rains have moved into the northern half of the state, with over an inch recorded north of the Golden Gate Bridge in Marin County. Check the blogs of our San Francisco-based meteorologists Dr. Rob Carver and Shaun Tanner for updates today, in what promises to be a wild weather day for Northern California. The Sierras are expecting several feet of snow and wind gusts of 120 mph late today. You can follow the storm today using our interactive wundermap for coastal California or the Sierras.


Figure 1. Latest radar-estimated precipitation for the San Francisco region.

Tropical Storm Patricia headed towards Baja
Tropical Storm Patricia is headed for Mexico's Baja Peninsula, but appears to be weakening. Latest satellite loops of Patricia show that the intensity and areal coverage of the storm's heavy thunderstorms has decreased in recent hours, and moderate wind shear of 10 knots appears to be elongating the cloud pattern into an unhealthly, non-circular shape. Patricia is over warm sea surface temperatures (29°C), and wind shear may fall into the low range (5 - 10 knots) later today, so the weakening may be temporary. An Air Force Hurricane Hunter aircraft is on call to fly the storm this afternoon at 2pm EDT to find out more information. While most of the computer model turn Patricia out to sea to the west before reaching Baja, the storm will probably come close enough to the southern tip of the peninsula to bring wind gusts of 40 mph and rains of 1 - 3 inches. The HWRF model is an outlier, and brings Patricia to the coast of Baja as a Category 1 hurricane. Given Patricia's recent struggles, this solution appears unlikely, and the official NHC track keeping Patricia offshore looks like a good one.

Destructive Tropical Storm Parma making its fifth landfall
Tropical Storm Parma, which traversed the northern portion of the Philippines' Luzon Island three times last week, is making a fifth landfall tomorrow, over northern Vietnam. Parma hit China's Hainen Island yesterday, killing three and causing millions in damage. The death toll from Parma's rains in the Philippines is over 300, on top of the 300 killed by Typhoon Ketsana two weeks prior. Most of Parma's victims were in the mountainous Cordillera region, where more than 40 landslides killed 227 people. Parma dumped over 26 inches of rain in a one-week period over the mountain town of Baguio. Parma has been alive for 16 days, which is a very long time, but far from the record 30-day life span of Typhoon John of 1994.

Quiet in the Atlantic
There are no threat areas in the Atlantic to discuss, and none of the computer models are calling for tropical storm formation over the next seven days.

Jeff Masters

Hurricane

Updated: 6:35 PM GMT en Agosto 18, 2011

Permalink

Baja braces for Patricia; California getting soaked; contact your Senator

By: JeffMasters, 12:58 PM GMT en Octubre 12, 2009

In the Eastern Pacific, Tropical Storm Patricia is gathering strength, and should bring at least tropical storm force winds to Mexico's Baja Peninsula Tuesday night and Wednesday morning. Latest satellite loops of Patricia show that the storm has developed an impressive burst of heavy thunderstorms with very cold cloud tops. Patricia is in an environment of low wind shear (5 - 10 knots) and warm sea surface temperatures (29°C), and these conditions are expected to change little over the next 48 hours. This may give Patricia enough time to strengthen into a Category 1 hurricane, as predicted by the latest 2am EDT runs of the GFDL and HWRF models. While most of the computer models indicate that Patricia will turn to the west out to sea Wednesday as the storm makes its closest approach to Baja, the HWRF model predicts the storm will grow large and strong enough to be influenced by a trough of low pressure to the north, and track into the Gulf of California and make landfall in mainland Mexico.


Figure 1. Latest satellite image of Patricia.

Typhoon Melor's remains poised to soak California
The remains of Super Typhoon Melor, which hit Japan last week, are just off the California coast this morning, and are poised to deliver record rains to the northern portion of the state tonight through Wednesday. Meteorologist Dr. Rob Carver in our San Francisco office is predicting in his blog that he'll need a kayak to commute into work tomorrow, and the Sierras are expecting several feet of snow and 120 mph winds.

Destructive Tropical Storm Parma making its fourth landfall
Tropical Storm Parma, which traversed the northern portion of the Philippines' Luzon Island three times last week, is making a fourth landfall today over China's Hainen Island. The death toll from Parma's rains has now exceeded 300, on top of the 300 killed in the Philippines from Typhoon Ketsana two weeks prior. Most of Parma's victims were in the mountainous Cordillera region, where more than 40 landslides killed 227 people. Parma dumped over 26 inches of rain in a one-week period over the mountain town of Baguio.

Contact your Senators today on tomorrow's vote to slash NOAA funding
As I reported in Saturday's post, I urge all of you who value the services provided by the National Weather Service and their parent organization, the National Oceanic and Atmospheric Administration (NOAA), to contact your two Senators and ask them to vote against the Senator Hutchison (R-TX) Amendment #2666 to the Commerce State Justice Appropriations Act for 2010 H.R. 2847. This amendment will be voted on this Tuesday, October 13, by the Senate, and would cut the NOAA budget by $172 million. The funds would be diverted to the State Criminal Alien Assistance Program, to increase its budget by 75%. While I'm sure the State Criminal Alien Assistance Program is a worthy program to support, Congress should find a different way to fund this program. NOAA's total budget is about $4 billion, and the National Weather Service Budget is a little less than $1 billion. The only place where NOAA has the flexibility to absorb the proposed cuts would be in the satellite program. With the QuickSCAT satellite likely to fail in the next few months, and the Tropical Rainfall Measurement Mission (TRMM) satellite also nearing its demise, the last thing we should be doing is cutting NOAA's budget in time when our capability to observe the weather from space is suffering from serious degradation.

Quiet in the Atlantic
There are no threat areas in the Atlantic to discuss, and none of the computer models are calling for tropical storm formation over the next seven days.

Jeff Masters

Hurricane

Updated: 6:35 PM GMT en Agosto 18, 2011

Permalink

QuikSCAT satellite nearing failure; Congress poised to slash NOAA funding

By: JeffMasters, 2:50 PM GMT en Octubre 10, 2009

The QuikSCAT satellite, launched in 1999, provides crucial measurements of surface wind speed and direction over Earth's oceans twice per day. Forecasters world-wide have come to rely on data from QuikSCAT to issue timely warnings and make accurate forecasts of tropical and extratropical storms, wave heights, sea ice, aviation weather, iceberg movement, coral bleaching events, and El Niño. Just one example of QuikSCAT's value (H. Kite-Powell, 2008) is that wind data from QuikSCAT and the resulting improvements to warning and forecast services save the container and bulk shipping industry $135 million annually by reducing their exposure to hurricane force wind conditions in non-tropical storms by 44% over the North Pacific and North Atlantic. Originally expected to last just 2 - 3 years, QuikSCAT is now ten years old, and will be lucky to survive into 2010. NASA and NOAA notified Congress in September that there is a significant chance QuikSCAT will fail in the next few months. According to scientists at NASA's Jet Propulsion Laboratory, "the mechanism that maintains the constant 18 rpm rotation rate of the antenna that scans Earth's surface has grown steadily worse over the past six months. Engineering telemetry shows that the torque loss due to friction in the bearing system has been increasing at an alarming rate in recent weeks and that if the trend continues, the rotation speed will begin to slow significantly within the next few weeks or months. When that happens, scatterometer calibration and spatial sampling will be affected. Eventually the wind vector data products from QuikSCAT will no longer be reliable for operational forecasting. The timing is not predictable, but forecasters should anticipate loss of the QuikSCAT near-real-time data in the near future."


Figure 1. NASA's QuikSCAT satellite, launched in 1999. Image credit: NASA.

As I argued in a post earlier this year, "The case for a new QuikSCAT satellite", replacing QuikSCAT should be a high priority for Congress. The earliest a replacement satellite could be launched is 2015--if immediate action is taken to procure funding. Losing QuikSCAT is going to make it much more difficult to assess the strength and position of tropical storms over the open Atlantic, where the Hurricane Hunters cannot reach.

Senate vote Tuesday may significantly cut NOAA funding
I urge all of you who value the services provided by the National Weather Service and their parent organization, the National Oceanic and Atmospheric Administration (NOAA), to contact your two Senators and ask them to vote against the Senator Hutchison (R-TX) Amendment #2666 to the Commerce State Justice Appropriations Act for 2010 H.R. 2847. This amendment will be voted on this Tuesday, October 13, by the Senate, and would cut the NOAA budget by $172 million. The funds would be diverted to the State Criminal Alien Assistance Program, to increase its budget by 75%. While I'm sure the State Criminal Alien Assistance Program is a worthy program to support, Congress should find a different way to fund this program. NOAA's total budget is about $4 billion, and the National Weather Service Budget is a little less than $1 billion. The only place where NOAA has the flexibility to absorb the proposed cuts would be in the satellite program. With the QuickSCAT satellite likely to fail in the next few months, and the Tropical Rainfall Measurement Mission (TRMM) satellite also nearing its demise, the last thing we should be doing is cutting NOAA's budget in time when our capability to observe the weather from space is suffering from serious degradation.

Here's the language of the bill, and the proposed amendments:

SA 2666. Mrs. HUTCHISON (for herself, Mr. CORNYN, Mr. KYL, and Mr. MCCAIN) submitted an amendment intended to be proposed by her to the bill H.R. 2847, making appropriations for the Departments of Commerce and Justice, and Science, and Related Agencies for the fiscal year ending September 30, 2010, and for other purposes; which was ordered to lie on the table; as follows:

On page 170, between lines 19 and 20, insert the following:

SEC. 220. INCREASE IN STATE CRIMINAL ALIEN ASSISTANCE PROGRAM FUNDING.

(a) In General.--For an additional amount under the heading ``STATE AND LOCAL LAW ENFORCEMENT ASSISTANCE'' under the heading ``Office of Justice Programs'' under this title, there is appropriated, for the fiscal year ending September 30, 2010, $172,000,000 for the State Criminal Alien Assistance Program, as authorized by section 241(i)(5) of the Immigration and Nationality Act (8 U.S.C. 1231(i)(5)).

(b) Offset.--The total amount appropriated under the heading ``OPERATIONS, RESEARCH, AND FACILITIES'' under the heading ``National Oceanic and Atmospheric Administration'' under title I is reduced by $172,000,000.

The National Weather Service Employees Organization has put out a press release with more details.

Quiet in the Atlantic
A tropical wave (92L) that is moving along the northern coast of South America has only a very limited amount of heavy thunderstorms, thanks to interaction with land. There are no threat areas in the Atlantic to discuss, and none of the computer models are calling for tropical storm formation over the next seven days.

Please, Contact your Senators to oppose the proposed NOAA funding cut, and to argue for funding for a new QuikSCAT satellite.

I'll have a new post on Monday.

Jeff Masters

Updated: 2:51 PM GMT en Octubre 10, 2009

Permalink

Quiet in the Atlantic; Melor's rains headed for California; Parma kills 160

By: JeffMasters, 1:21 PM GMT en Octubre 09, 2009

Tropical Storm Henri is dead, killed by high wind shear. Henri's remains may bring some isolated heavy rain showers to Puerto Rice today, and San Juan radar is showing a large area of disorganized rain showers north of the island. Henri's remains will move over the northern portion of the Dominican Republic on Saturday, and northern Haiti on Sunday. At this time, it does not appear that Henri's remains will pose a flooding threat to any of the islands. Henri's remains have grown so disorganized that regeneration into a tropical depression is unlikely.

A tropical wave (92L) is over Trinidad and the northern coast of South America. This wave has lost most of its heavy thunderstorms due to interaction with land. The 8pm EDT run of the HWRF model indicated that 92L might be able to organize into a tropical depression, but none of the other models are calling for development. The disturbance is too close to the coast of South America for any development to occur for at least a day or two. NHC is giving 92L a low (less than 30% chance) of developing into a tropical depression by Sunday.


Figure 1. Morning satellite image of the remains of Henri just north of Puerto Rico and Invest 92L over Trinidad and the coast of South America.

Typhoon Melor's remains set to drench California
Typhoon Melor made landfall at 2 am local time on Thursday, October 8, in central Japan's Aichi prefecture (population 7 million), as a Category 1 typhoon with 75 mph winds. Melor is being blamed for 2 deaths and up to $1.5 billion in damage. Melor's remains will be paying a visit to California Monday through Wednesday, and the storm is expected to dump 1 - 3 inches of rain along the Northern California coast, and 3 - 6 inches in the hills and Sierra Mountains. High winds of 20 - 40 mph will accompany the rain. Though the heavy rains may cause some flooding problems, they will be more boon than burden--California is under moderate to severe drought.


Figure 2. Rainfall forecast for the period 5am PDT Monday through 5am PDT Wednesday. Heavy rains of up to six inches are expected over Northern California from the remains of Typhoon Melor. Image credit: NOAA/HPC.

Typhoon Parma kills 160 in the Philippines
Tropical Storm Parma has completed its third traverse over the Philippines' Luzon Island, and is now headed westward across the South China Sea towards China. Yesterday, rains from Parma's three crossings of northern Luzon triggered landslides that killed at least 160 people. At least 300 Filipinos died two weeks ago due to flooding from Typhoon Ketsana, and the sodden Philippines will finally get a chance to dry out with no more typhoons expected to visit for at least the next week.

The Washington Post posted an interesting story today on What Happened to Hurricane Season.

Jeff Masters

Hurricane

Updated: 8:57 PM GMT en Enero 04, 2012

Permalink

Henri nearly dead

By: JeffMasters, 1:38 PM GMT en Octubre 08, 2009

Tropical Depression Henri continues to suffer from high wind shear of 20 knots, and appears on its way to dissipation. Visible satellite loops show that the shear has exposed Henri's low level center to view, and this center has become less circular and not as well defined. Henri's heavy thunderstorms have been shrinking in areal coverage and intensity, and are displaced from the center--signs of a highly sheared tropical storm that has little time left to live.

All of the reliable global computer models show weakening and dissipation of Henri by Friday, due to high wind shear. Wind shear in the vicinity of Henri's remains is predicted to fall to the moderate range by Saturday, but at that time it appears that the storm will be moving over the Dominican Republic, which will disrupt whatever is left of the storm's circulation. Henri's remains may bring heavy rains of 2 - 4 inches the the Dominican Republic and Haiti Saturday through Monday. By Tuesday, the remains of Henri will likely be moving across Florida and/or Cuba and into the Gulf of Mexico, where we will need to watch the system for re-development.


Figure 1. Morning satellite image of Henri (top) and a new tropical wave we're watching (bottom). The tropical wave south of Henri, just off the coast of South America, has become disorganized.

Tropical wave south of Henri
A tropical wave south of Henri, just north of the coast of South America and a few hundred miles east-southeast of the southernmost Lesser Antilles Islands, has grown less organized since yesterday. Both the areal coverage and intensity of the heavy thunderstorm activity has decreased, and there are no signs of organization to the cloud pattern. This wave is under about 10 knots of wind shear, but is too close to the Equator to be able to take advantage of the Earth's spin to help it spin up into a tropical depression very quickly. Also, the wave may pull in some dry, stable air from South America as it scoots just north of the coast over the next few days. NHC is giving this disturbance a low (less than 30% chance) or developing into a tropical depression by Saturday. There are no computer models showing development of this system.


Figure 2. Tropical Storm Parma (left) and Typhoon Melor (right) on October 7, 2009. At the time, Melor was a Category 4 typhoon with 135 mph winds, and Parma was a tropical storm with 60 mph winds. The two storms were close enough together that they rotated around a common center counter-clockwise, in an interaction known as the Fujiwara Effect. This forced Parma to reverse course and pass over the Philippines from west to east, after the storm had already crossed the islands from east to west. Now that Melor is gone, Parma is crossing the Philippines once more from east to west. Image credit: NASA Earth Observatory.

Typhoon Melor
Typhoon Melor made landfall yesterday on Japan's Honshu Island south of Osaka as a Category 1 typhoon with 85 mph winds. The typhoon killed two people and caused some moderate damage to the coastal region of southern Japan where it came ashore.

In the Philippines, Tropical Depression Parma is making its third traverse over the Philippines' Luzon Island. is expected to dump up to six more inches of rain today over the already sodden portions of northern Luzon. The storm is being blamed for 22 deaths and millions in agricultural damage.

Jeff Masters

Hurricane

Updated: 6:36 PM GMT en Agosto 18, 2011

Permalink

Henri being torn apart by shear

By: JeffMasters, 7:21 PM GMT en Octubre 07, 2009

Tropical Storm Henri is getting ripped apart by wind shear, and is much less organized than it was early this morning. About 25 knots of wind shear continues to eat into storm, and visible satellite loops show that the shear has exposed Henri's low level center to view. Henri's heavy thunderstorms have been shrinking in areal coverage and intensity, and are steadily moving away from the center--all signs of a highly sheared tropical storm that has little time left to live.

All of the reliable global computer models show weakening and dissipation of Henri by Thursday, due to high wind shear. Wind shear in the vicinity of Henri's remains is predicted to fall to the moderate range by Saturday, so we will have to be concerned with regeneration after Henri dissipates. It appears likely that moisture from Henri will affect Puerto Rico by Friday night, the Dominican Republic on Saturday, and Haiti on Sunday. It is too early to tell if Henri's remains will be capable of causing flooding rains in these regions.


Figure 1. Afternoon satellite image of Henri (top) and a new tropical wave we're watching (bottom). The tropical wave south of Henri, just off the coast of South America, has become more organized this afternoon. The thunderstorm activity has grown more concentrated near 8N 50W, with a hint of some low-level spiral banding starting to form. This wave is under about 10 knots of wind shear, but is too close to the Equator to be able to take advantage of the Earth's spin to help it spin up into a tropical depression very quickly. Also, the wave will suffer from interaction with the coast of South America on Thursday. NHC is giving this disturbance a low (less than 30% chance) or developing into a tropical depression by Friday.

Typhoon Melor
Typhoon Melor has made landfall on Japan's Honshu Island south of Osaka as a Category 1 typhoon with 85 mph winds. Hamamatsu reported sustained winds of 54 mph last hour, and tropical storm force wind gusts will be common along much of the south coast of Honshu as the typhoon passes. You can follow the landfall of Melor with our interactive wundermap for the region.

Jeff Masters

Hurricane

Updated: 6:36 PM GMT en Agosto 18, 2011

Permalink

Henri hanging on in the face of high wind shear

By: JeffMasters, 1:31 PM GMT en Octubre 07, 2009

Our second October surprise this week in the Atlantic, Tropical Storm Henri, continues to defy 25 knots of wind shear. Henri has strengthened to a 50 mph tropical storm this morning, but wind shear is keeping the storm's heaviest thunderstorms confined to the southeast side of the circulation. Satellite loops show that Henri's low level center is exposed to view, and that the heavy thunderstorms may be retreating from the center, a sign that shear could be starting to rip the storm apart. This morning's QuikSCAT pass missed Henri, and last night's pass showed winds of 40 - 45 mph.

All of the reliable global computer models show weakening and dissipation of Henri by Thursday, due to high wind shear. The official NHC forecast goes along with this scenario, and I'll go along, given the unanimity and persistence of the models in forecasting this. Wind shear in the vicinity of Henri's remains is predicted to fall to the moderate range by Saturday, so we will have to be concerned with regeneration after Henri dissipates. It appears likely that moisture from Henri will affect Puerto Rico by Friday, the Dominican Republic on Saturday, and Haiti on Sunday. It is too early to tell if Henri's remains will be capable of causing flooding rains in these regions.


Figure 1. Morning satellite image of Henri (top) and a new tropical wave we're watching (bottom). The tropical wave south of Henri, just off the coast of South America, has become more organized this morning. This wave is under about 10 knots of wind shear, but is too close to the Equator to be able to take advantage of the Earth's spin to help it spin up into a tropical depression very quickly. NHC is giving this disturbance a low (less than 30% chance) or developing into a tropical depression by Friday.

Pacific typhoons
In the Philippines, Tropical Storm Parma completed its second traverse of the Philippines' Luzon island, and has emerged over the Philippine Sea to the east of the country. Parma is expected to reverse course and cross Luzon a third time over the next three days. Parma is expected to dump another 1 - 2 inches of rain today on northern Luzon.

Typhoon Melor has weakened to a Category 2 typhoon with 100 mph winds, thanks to high wind shear and cool ocean waters. The typhoon should weaken to Category 1 strength before making landfall near 3am Japanese time on the main island of Honshu, just south of Osaka. Melor will probably bring sustained winds of 40 mph to Tokyo. You can follow the landfall of Melor with our interactive wundermap for the region. Several coastal locations are already reporting sustained winds near 40 mph.

Some tropical weather for England
The remnant circulation of Tropical Storm Grace made landfall in Southwest England last night. Grace's remains brought sustained winds of tropical storm force--41 mph--to one buoy off the coast, and 38 mph to the Sevenstones Lightship buoy.


Figure 2. The remnant circulation of Tropical Storm Grace scoots by to the south of Ireland in this visible satellite image taken at 1pm EDT 10/06/09. Image credit: UK Met Office.

I'll have an update late this afternoon.

Jeff Masters

Hurricane

Updated: 6:37 PM GMT en Agosto 18, 2011

Permalink

Tropical Storm Henri forms

By: JeffMasters, 9:37 PM GMT en Octubre 06, 2009

The tropics spawned another October surprise today, when Tropical Storm Henri formed in the face of adverse levels of wind shear. Henri is under about 20 - 25 knots of wind shear, which ordinarily prevents rapid development like we witnessed this afternoon. However, the environment is quite moist, and Henri is over warm waters, 29°C. An ASCAT pass from 11:37am EDT showed Henri had winds of 40 mph. Satellite loops show that Henri has managed to rapidly develop a large area of intense thunderstorms with cold cloud tops in just a few hours, though the high shear is keeping any thunderstorms from developing on the west side of the center. Water vapor satellite images show that there is some dry air to Henri's northwest, and this dry air will act to slow Henri's growth some. The dry air is creating strong downdrafts that are apparent on visible satellite images as arcs of cumulus clouds spreading out from where the downdraft hits the ocean surface, along the northwest side of Henri's center.

None of the reliable global computer models showed Henri would develop, and the models all favor weakening and dissipation of Henri by Thursday, due to high wind shear of 20 - 25 knots. The official NHC forecast goes along with this scenario, but think there is a medium (30 - 50% chance) that Henri will not dissipate. By Friday, wind shear in the vicinity of Henri (or its remains) is predicted to fall to the low to moderate range. Even if Henri has dissipated by that point, regeneration into a tropical storm may occur. The track of Henri after Friday is problematic, as the storm will be in an area of weak steering currents. Several of the models favor a track to the west-southwest into the Caribbean, across Hispaniola. Residents of the Dominican Republic and Haiti should anticipate that Henri or its remains may bring flooding rains to Hispaniola by Saturday. It is also possible that Henri will get pulled northwards and recurved out to sea, and not affect the Caribbean at all, though.


Figure 1. Latest satellite image of Henri.

A little tropical weather for England
The remnant circulation of Tropical Storm Grace is currently making landfall in Southwest England. Grace's remains brought sustained winds of tropical storm force--41 mph--to one buoy off the coast last hour, and 38 mph to the Sevenstones Lightship buoy. you can track the progress of Grace via our wundermap for the region.


Figure 2. The remnant circulation of Tropical Storm Grace scoots by to the south of Ireland in this visible satellite image taken at 1pm EDT 10/06/09. Image credit: UK Met Office.

Jeff Masters


Hurricane

Updated: 6:37 PM GMT en Agosto 18, 2011

Permalink

91L develops a closed circulation; monsoon floods in India kill over 250

By: JeffMasters, 2:06 PM GMT en Octubre 06, 2009

A tropical wave (91L) near 17N, 52W, about 550 miles east of the Lesser Antilles Islands, continues to generate considerable heavy thunderstorm activity as it moves northwest at 15 mph. The wave is under high wind shear, 20 - 25 knots, and is over warm waters, 29°C. This morning's QuikSCAT pass showed no closed circulation, and top winds of 30 mph. However, satellite loops show that 91L now has a closed surface circulation, though strong upper-level winds out of the west are keeping the heavy thunderstorm activity confined to the east side of the center. Since there is not much dry air to the storm's west, the shear will not have as great a negative impact as we've seen in similar high-shear situations this year.

None of the computer models develop the wave, and they show moderate to high wind shear affecting 91L over the next 2 - 3 days. The storm will be steered northwest for the next 2 - 3 days by a trough of low pressure passing to the north. The northern Lesser Antilles may see some heavy rain showers and gusty winds from the southern portion of 91L on Thursday and Friday. By Friday, the trough will have passed far to the east, and high pressure will build in, which may force 91L to the southwest into the Caribbean, according to some model projections. Wind shear is expected to fall to the low to moderate range 3 - 5 days from now. If 91L holds together for the next 2 - 3 days and avoids interaction with the high mountains of Hispaniola late this week, the storm could be trouble. NHC is currently giving 91L a low (less than 30% chance) of developing into a tropical depression by Thursday, and the Hurricane Hunters are not on call to fly the storm. I think the storm has more potential to develop than NHC does, and put the odds of development over the next two days at medium (30 - 50%).


Figure 2. latest images of Invest 91L.

Pacific typhoons
In the Philippines, Tropical Storm Parma circled back and has struck the northwest corner of the Philippines' Luzon island today. Parma dumped over sixteen inches of rain on northern Luzon in its first pass over the island last weekend, and is expected to dump another 1 - 2 inches today.

Typhoon Melor has weakened to a Category 3 typhoon south of Japan, and is expected to hit Japan Thursday morning as a Category 2 storm. Melor is expected to track near or over Tokyo as a tropical storm on Thursday afternoon.

Monsoon floods in India kill 269
India's monsoon officially ended on October 1, but an unusually slow-to-depart monsoon dumped unprecedented rains in Karnataka and Andhra Pradesh states in southern India over the past week, generating massive flooding that has killed at least 269 people and left 2.5 million homeless. Rainfall last Thursday in the city of Karwar exceeded .5 meters (19 inches) in a single day. Rain from the deluge ran off into the Krishna River in Andhra Pradash state, where the local information minister stated, "This is known as PMF or possible maximum flood, which happens once in 10,000 years".

Disastrous monsoon floods are common in India and surrounding nations, and the annual death toll from monsoon floods exceeds 1,000 in India, Bangladesh, Nepal, and Pakistan. Over 2,000 people died last year in monsoon floods in South Asia. The greater concern is when the monsoon rains fail, as sometimes happens during El Niño years. This year's El Niño led to substantial drought over much of India, and the 2009 Indian Monsoon is among the five worst monsoons in the recorded history (since 1871). The five worst monsoons along with the rainfall deficits for India have been:

1) 1877, -33%
2) 1899, -29%
3) 1918, -25%
4) 1972, -24%
5) 2009, -23%

Up until the late 1960s, it was common for the failure of the monsoon rains to kill millions of people in India. The drought of 1965 - 1967 killed at least 1.5 million people. However, since the Green Revolution of the late 1960s--a government initiative to improve food self-sufficiency using new technology and high-yield grains--failure of the monsoon rains has not led to mass starvation in India. While there are concerns about food shortages due to the summer drought, and now the October monsoon floods, the days of mass starvation in India due to drought and flood are past, thankfully.

Climate change poses a significant challenge to India, as more intense droughts and greater floods are likely to occur in India as the climate warms. Wunderground's climate change blogger Dr. Ricky Rood just completed a trip to India, and wrote a nice 3-part series about the challenges India faces due to climate change.


Figure 2. Rainfall this year in India has been 23% below average, the 5th worst monsoon since 1871. Image credit: India Meteorological Department.

A plug for Portlight
The Portlight.org disaster relief charity has been doing some great work this past week, and delivered a truck full of relief supplies over the weekend to victims of the Atlanta, GA floods. Portlight is also preparing a shipment of supplies for disabled people to the tsunami victims of Samoa. If you haven't stopped by their blog lately, take a look at the latest stories and photos.

Jeff Masters

Hurricane

Updated: 6:37 PM GMT en Agosto 18, 2011

Permalink

Surprise tropical storm forms near the Azores; Invest 91L has potential to develop

By: JeffMasters, 2:19 PM GMT en Octubre 05, 2009

Surprise! A 70-mph tropical storm popped up seemingly out of nowhere early this morning, in a region of the Atlantic not ordinarily prone to tropical storm formation. Tropical Storm Grace formed at 41.2° north latitude, in a remote ocean area near the Azores Islands. This is the farthest northeast an Atlantic tropical storm has ever formed since satellite observations began in the 1960s. Since 1960, only one tropical storm has formed farther north--Tropical Storm Alberto of 1988, which formed at 41.5°N, off the coast of Cape Cod, Massachusetts. Satellite imagery revealed that Grace formed an eyewall and well-defined eye this morning, though the storm's tropical storm-force winds did not extend out very far from the center. Last night, the center of Grace passed about 20 miles west of Ponta Delgada in the eastern Azores, which recorded sustained winds of 31 mph, gusting to 44 mph. Grace formed over chilly waters of about 23°C, well below the usual threshold of 26°C required for tropical storm formation. Grace's formation was aided by some very cold temperatures in the upper atmosphere (-54°C at 200 mb), which made the atmosphere more unstable than usual. The storm won't be around much longer, as Grace is already over much colder waters of 21°C, and is headed towards even colder waters.


Figure 1. The storm that would later become Tropical Storm Grace passes through the Azores Islands at 14:20 UTC 10/04/09. Image credit: NOAA/CIRA.

Invest 91
A large tropical wave near 12N 46W, about 1000 miles east of the Lesser Antilles Islands, is generating a considerable amount of heavy thunderstorm activity as it moves west-northwest at 15 mph. The wave is under low wind shear, 5 - 10 knots, and is over warm waters, 29°C, which is 3°C above the threshold typically needed to allow tropical storm formation. Last night's QuikSCAT pass showed a large and disorganized region of converging winds in the region, with top winds of 25 mph. There is very little dry air in the vicinity, and conditions appear favorable for some slow development of this wave. The wave is poorly organized at present, with no signs of a surface circulation visible on satellite imagery. None of the computer models develop the wave, but they do show relatively low wind shear along the wave's path for the next five days. The wave should continue to track west-northwest over the next 2 - 3 days, and spread heavy rain showers over the northern Lesser Antilles Islands by Wednesday. By Thursday, the trough of low pressure that is pulling 91L to the north should bypass the storm, allowing a high pressure ridge to build in and force 91L due west. NHC is giving 91L a low (less than 30% chance) of developing into a tropical depression by Wednesday.


Figure 2. latest images of Invest 91L.

Pacific typhoons
In the Philippines, the cleanup continues from Tropical Storm Parma, which hit northern Luzon Island Saturday as a Category 1 typhoon. Parma continues to linger offshore the northern tip of the Philippines' Luzon Island, but its heavy rain is now offshore the Philippines. The storm has been blamed for the deaths of 16 people in the Philippines, but did not have the devastating impact that was earlier feared. Storm chaser James Reynolds took some dangerous looking video of Parma in the Philippines.

Super Typhoon Melor became the second Category 5 tropical cyclone of the year over the weekend, but has weakened slightly to a Category 4 super typhoon with 155 mph winds. Melor is expected to recurve to the northeast and pass within 200 miles of Tokyo, Japan, on Wednesday night or Thursday morning.

Jeff Masters

Hurricane

Updated: 6:37 PM GMT en Agosto 18, 2011

Permalink

An Atlantic tropical wave worth watching

By: JeffMasters, 2:46 PM GMT en Octubre 04, 2009

A large tropical wave near 9N 40W, midway between Africa and the Lesser Antilles Islands, is generating a considerable amount of heavy thunderstorm activity as it moves west to west-northwest at 15 mph. The wave is under about 10 - 15 knots of wind shear, and this morning's QuikSCAT pass showed a large and disorganized region of converging winds in the region, with top winds of 25 mph. There is very little dry air in the vicinity, and conditions appear favorable for some slow development of this wave. None of the computer models develop the wave, but they do show relatively low wind shear along the wave's path for the next five days. The wave should reach the Lesser Antilles Islands by Wednesday.


Figure 1. The large tropical wave in the middle Atlantic.

In the Philippines, Tropical Storm Parma continues to linger offshore the northern tip of the Philippines' Luzon Island, bringing heavy rain. The storm has been blamed for the deaths of 17 people in the Philippines, but has not not had the devastating impact that was earlier feared. Parma's heaviest rains will stay offshore of the Philippines today (Figure 2).


Figure 2. Forecast rain amounts for Parma for the 24-hour period ending at 06 UTC October 5 (2am EDT Monday). This forecast is based on satellite measurements of Parma's current rainfall rate, plus a projection of the storm's path. Four to eight inches of rain (yellow colors) is expected along the extreme northwest tip of Luzon Island. Image credit: NOAA Satellite Services Division.

Super Typhoon Melor hits Cat 5 strength
Super Typhoon Melor has become the second Category 5 tropical cyclone of the year. Melor is expected to recurve to the north pass just south of the coast of Japan later this week.

Jeff Masters

Hurricane

Updated: 6:38 PM GMT en Agosto 18, 2011

Permalink

Typhoon Parma hits the Philippines as a Catgeory 1 typhoon

By: JeffMasters, 3:02 PM GMT en Octubre 03, 2009

Typhoon Parma made landfall as a Category 1 typhoon with 90 mph winds and torrential rains over the northern portion of the Philippines' Luzon Island early Saturday morning. Parma had been a very dangerous Category 4 typhoon just 24 hours prior to landfall, but interaction of the storm with the high mountain range along the Philippines' east coast disrupted the storm as it approached landfall. As a result, Parma is dumping less rain than feared, and its path along the extreme northern coast of Luzon is keeping the typhoon's rains well north of the capital of Manila, which is still recovering from the 16+ inches of rain dumped by Typhoon Ketsana a week ago. A query of airports in northern Luzon Island done using our interactive wundermap reveals that Parma has dumped between two and six inches of rain over the past two days. Some isolated regions may receive up to twenty inches of rain, according to the latest satellite-based rainfall forecast for Parma (Figure 2). While rains of this magnitude will cause significant damage to localized regions, a major disaster with hundreds of lives lost now appears unlikely in the Philippines due to Typhoon Parma.


Figure 1. Total estimated rainfall from last weeks's Typhoon Ketsana, as estimated by NASA's TRMM satellite. Image credit: NASA/TRMM project.


Figure 2. Forecast rain amounts for Typhoon Parma for the 24-hour period ending at 06 UTC October 4 (2am EDT Sunday). This forecast is based on satellite measurements of Parma's current rainfall rate, plus a projection of the storm's path. Over twelve inches of rain (red colors) is expected along the extreme northern tip of Luzon Island. Image credit: NOAA Satellite Services Division.

Typhoon Melor
Category 4 Typhoon Melor powered through the northern Marianas Islands 90 miles north of Saipan Island this morning. Melor brought sustained winds of 32 mph to Saipan. Melor is expected to recurve to the north pass just south of the coast of Japan next week.

The Atlantic remains quiet
In the Atlantic, there are no threat areas to discuss and none of the computer models are forecasting tropical storm formation over the next seven days.

Atlanta flood relief mission today
The portlight.org charity is delivering a load of relief supplies to one of the families affected by the Atlanta, Georgia floods two weeks ago. You can follow the progress of the mission via the portlight.org webcam today.

Jeff Masters

Hurricane

Updated: 6:38 PM GMT en Agosto 18, 2011

Permalink

Typhoon Parma: a new disaster for Asia

By: JeffMasters, 2:59 PM GMT en Octubre 02, 2009

Asia's terrible natural disasters of the past week will soon have new company--Typhoon Parma, a Category 4 storm with 135 mph winds and torrential rains, is poised to strike the northern portion of the Philippines' Luzon Island on Saturday. Also of concern is Category 4 Typhoon Melor, which may attain super typhoon status (150 mph winds) as it passes though the northern Marianas Islands near Saipan Island on Saturday. Melor is expected to recurve to the north, and may strike Japan late next week.

Typhoon Parma weakened some yesterday as its rain began spreading over the Philippines, thanks to 20 knots of hostile wind shear from strong upper-level winds. The Joint Typhoon Warning Center is rating Parma a Category 4 storm with 135 mph winds, but satellite intensity estimates from NOAA and the Japan Meteorological Agency put Parma at Category 2 strength. Regardless, Parma will be an extremely dangerous storm for the Philippines due the heavy rain it will bring. Microwave satellite estimates of Parma's rainfall (Figure 1) show that the typhoon is producing up to 1.3 inches per hours of rain. Given the slow movement of the storm, Parma is capable of bringing over twelve inches of rain to coastal Luzon Island over the next 24 hours. The situation worsens Saturday and Sunday, as steering currents are expected to collapse, and Parma may sit just offshore, dumping prodigious amounts of rain on soils already saturated by Typhoon Ketsana a week ago. The potential exists for portions of northern Luzon Island to receive over twenty inches of rain from Parma, which would likely destroy most of the transportation and communications infrastructure and create life-threatening flash floods and mudslides. Parma has the potential to become one of the ten most damaging typhoons in Philippines history.


Figure 1. Estimated rainfall rate for Typhoon Parma at 11:01 UTC on 10/02/09, as estimated by a microwave instrument on the polar-orbiting F-16 satellite. Image credit: Naval Research Lab, Monterey.


Figure 2. Forecast rain amounts for Typhoon Parma for the 24-hour period ending at 12 UTC October 3 (8am EDT Saturday). This forecast is based on satellite measurements of Parma's current rainfall rate, plus a projection of the storm's path. Over twelve inches of rain (red colors) is expected along a portion of the typhoon's path. A few tiny areas of 20+ inches (purple colors) also appear in the forecast. Image credit: NOAA Satellite Services Division.

Mobilizing for Parma and Melor
Philippines President Arroyo has already declared a nationwide "state of calamity" and ordered six provincial governments to evacuate residents from flood- and landslide-prone areas in the path of the Parma. Going against the flow of evacuees will be Typhoon chasers James Reynolds and Geoff Mackley, who plan to travel to northern Luzon today to intercept Typhoon Parma. You can follow their progress at typhoonfury.com and rambocam.com. In addition, storm chaser Jim Edds is on Saipan Island waiting for Typhoon Melor to arrive; you can track his experiences at www.extremestorms.com.

The Atlantic remains quiet
A non-tropical low pressure system gave the Azores Islands some wind gusts over 40 mph yesterday, and NHC labeled this system "Invest 90L". However, this system is not a threat to develop into a tropical depression, as water temperatures are a chilly 23°C in the region. None of the computer models are forecasting tropical storm formation over the next seven days.

Jeff Masters

Hurricane

Updated: 6:39 PM GMT en Agosto 18, 2011

Permalink

Super Typhoon Parma threatens the Philippines; October hurricane season outlook

By: JeffMasters, 2:20 PM GMT en Octubre 01, 2009

It's been a terrible week for natural disasters in Asia, with the death toll from two huge earthquakes and Typhoon Ketsana continuing to mount. The bad news got worse today with the emergence of Super Typhoon Parma, now poised strike the northern portion of the Philippines' Luzon Island as a Category 4 typhoon with 150 mph winds. Also of concern is Category 3 Typhoon Melor, which has just undergone a period of rapid intensification, and is also approaching super typhoon status. A super typhoon is a storm with 150 mph winds or higher--a strong Category 4. Melor is forecast to pass through the northern Marianas Islands north of Guam and Saipan this weekend, then curve to the north and threaten Japan next week.

Super Typhoon Parma intensified dramatically early this morning, forming a tiny "pinhole" eye (Figure 1) only seen in very intense tropical cyclones. The last Atlantic hurricane to form a pinhole eye was Hurricane Wilma, the strongest Atlantic hurricane of all time. Parma's outer spiral bands are already beginning to spread over the eastern positions of the Philippines, and beginning Friday will likely bring 2 - 4 inches of rain to the regions hard-hit by Typhoon Ketsana, including the capital of Manila. More seriously, the super typhoon may make landfall along the northeastern portion of Luzon Island in the Philippines on Saturday as a Category 4 or 5 typhoon. The uncertainty in the forecast is very high, as steering currents are expected to weaken on Friday, and the presence of Typhoon Melor to the northeast introduces an additional element of uncertainty. It is quite possible that Parma will stall near or just offshore the northern coast of Luzon Saturday through Sunday as a super typhoon, dumping rainfall in excess of a foot over northern Luzon, as forecast by the ECMWF model. Northern Luzon received 2 - 4 inches of rain from Typhoon Ketsana last week, and an additional 12+ inches of rain falling on soils already saturated from Ketsana's rains would likely cause severe flash flooding and major landslides capable of killing hundreds. Another dismal possibility is offered by the NOGAPS model, which forecasts that Parma will cross directly over Luzon north of Manila, bringing heavy rains in excess of six inches to Manila, where more than 16 inches of rain fell Saturday during Typhoon Ketsana. It is also possible that Parma will miss the Philippines, staying far enough offshore that the Philippines will not suffer a major flooding disaster. However, the odds current favor another major typhoon disaster for the Philippines this weekend.


Figure 1. Super Typhoon Parma at 02:25 UTC on 10/01/09. Parma had developed a tiny pinhole eye, and the outer spiral bands were beginning to affect the eastern Philippines. Image credit: NASA.

October hurricane outlook
In the first half of October, Atlantic tropical cyclone activity remains quite high, before a sharp drop occurs around October 15. Since the current active hurricane period began in 1995, the first half of October has given birth to an average of 1.9 named storms, 0.7 hurricanes and 0.4 intense hurricanes. For the entire month of October, these figures are 3.9 named storms, 1.2 hurricanes, and 0.6 intense hurricanes. These numbers are about double the long-term climatological averages for the past 100 years.

The most typical track for October hurricanes is through the Western Caribbean, with recurvature to the north and northwest into the Gulf of Mexico or across Cuba and through the Bahamas. The jet stream becomes more active and moves further south in October, making recurving storms more likely, and eliminating long-track Cape Verdes-type hurricanes from making direct strikes on the U.S. East Coast or Texas. There have only been nine hurricanes that have hit the U.S. East Coast north of Miami in October or later, and only three on the Texas coast. For the U.S., the highest risk areas for an October hurricane strike are between central Louisiana and Southeast Florida. About 71% of the 53 hurricanes that have hit the U.S. after October 1 have struck this region. Here is a breakdown of the number of hurricane strikes by state between 1851 - 2008 occurring October or later:

Texas 3
Louisiana 9
Mississippi 2
Alabama 0
Florida Gulf Coast 25 (7 of these in the Panhandle)
Southeast Florida 3
Georgia 2
South Carolina 3
North Carolina 4
New England 2

There have been no direct strikes by hurricanes on the east coast of Florida north of Miami in October or later. However, the east coast of Florida is still capable of getting damaging hurricane conditions from storms that strike the Gulf Coast of Florida and move eastwards, as Hurricane Wilma of 2005 proved.


Figure 2. Tracks of all hurricanes and tropical storms forming October 1 - 15, 1851 - 2006.

There are no threat areas in the Atlantic to discuss today, and none of the computer models are forecasting tropical storm formation over the next seven days. However, the last few runs of the 16-day GFS model forecast for wind shear have been predicting a decline in wind shear over the Caribbean after October 12, so there may be a greater chance of tropical storm formation as we head into mid-October. Sea Surface Temperatures (SSTs) are certainly warm enough to support a major hurricane anywhere in the tropical Atlantic or Gulf of Mexico, and are more than 1°C above average (Figure 3).


Figure 3. Departure of Sea Surface Temperature from average for October 1, 2009. SSTs were about 1°C above average over the tropical Atlantic and Gulf of Mexico. Note the very warm anomalies over the East Pacific off the coast of South America, the signature of an El Niño event. Image credit: NOAA/SSD.

Wind shear
Wind shear has been much above average over the tropical Atlantic over the past month, which is typical for an El Niño year, though part of this shear is due to the above-average number of upper-level troughs of low pressure over the Atlantic this hurricane season. El Niño conditions in the Eastern Pacific have remained essentially unchanged over past few weeks, and are expected to intensify in the coming months, so we can expect a continuation of above-average wind shear over the Atlantic for the remainder of hurricane season. Wunderblogger Weather456 has posted a nice October hurricane outlook that goes into a bit more detail than I've done here for those interested.

The forecast
The last Atlantic hurricane season that was this quiet was the strong El Niño year of 1997. That year, we got two weak 45-mph tropical storms in October to finish out the season. I predict that for this season, we will also finish out the year with two more named storms, with one of these reaching hurricane strength. The most likely land areas such a storm might affect are along the Western Caribbean, Gulf Coast of Florida, and the Bahamas. The most likely time these storms may form is the period October 13 - November 7.

Jeff Masters

Hurricane

Updated: 6:39 PM GMT en Agosto 18, 2011

Permalink

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.