Dr. Jeff Masters' WunderBlog

Hurricane seasons ends; did all of this season's storms deserve names?

By: JeffMasters, 2:33 PM GMT en Noviembre 30, 2007

The Atlantic hurricane season of 2007 is over, and it was a strange one. For the second straight year, we had a near average season, despite pre-season predictions of a very active season. The U.S. got off lightly for the second straight year. Just two tropical storms and a Category 1 hurricane hit the country. Humberto, which did $500 million in damage to Texas and Louisiana, was our only hurricane. However, it was devastating year in the Caribbean. Two Category 5 hurricanes, Dean and Felix, barreled through, two weeks apart. Dean killed at least 27 along its trail of destruction through the Lesser Antilles Islands, Jamaica, and Mexico, while Felix was responsible for 235 people killed or missing in Nicaragua. The Caribbean also suffered deadly flooding rains from Hurricane Noel, which killed at least 150 people in the Dominican Republic and Haiti.

Records set in 2007
1) Hurricane Felix set the Atlantic record for fastest intensification from the first advisory to a Category 5 hurricane. It took Felix just 54 hours to accomplish the feat.

2) Hurricane Humberto set the Atlantic record for fastest intensification from first advisory issued to hurricane strength--18 hours. (Actually, Humberto did the feat in 14 1/4 hours, but this will get rounded off to 18 hours in the final data base, which stores points every six hours). There have been six storms that accomplished the feat in 24 hours.

3) Hurricane Lorenzo tied the Atlantic record for fastest intensification from a tropical depression to a Category 1 hurricane--twelve hours.

4) With the occurrence of Dean and Felix, there have now been eight Category 5 storms in the past five years--the highest total ever observed over such a short time span.

5) Dean and Felix both made landfall at Category 5 strength, the first time two storms have done that in a single year.



Figure 2. Atlantic 2007 hurricane season forecasts issued near June 1, compared to the actual and normal values.

CSU=Colorado State University (CSU) Phil Klotzbach/Dr. Bill Gray forecast (May 31)
NOAA=NOAA's forecast (May 22)
TSR=Tropical Storm Risk, Inc. (TSR) forecast (June 4)
UKMET=UK Met Office (June 19)
ACE=Accumulated Cyclone Energy, a measure of a named storm's potential for wind and storm surge destruction defined as the sum of the square of a named storm's maximum wind speed (in 10^4 knots^2) for each 6-hour period of its existence. The 1950-2000 average value of ACE is 96.

While 2007 was a fairly normal year in terms of number of hurricanes and intense hurricanes, it was above normal in terms of number of named storms (14, vs. an average of 11). However, this is a misleading measure of how active the hurricane season was. Seven of this year's storms were weak tropical storms that lasted a day and a half or less. Three of the hurricanes lasted only one advisory at hurricane strength (six hours). The total destructive energy (ACE, or Accumulated Cyclone Energy) for 2007 was only 71% of normal. Only 33.50 named storm days occurred in 2007, the lowest value of named storm days since the El Nino year of 1994, when 27.75 named storm days occurred.

Did all of the named storms this year deserve names?
While all of this year's named storms did reach tropical storm strength, based on the best data available, it is quite likely that two or more of them would not have gotten named 20 or more years ago. For example, Tropical Storm Melissa was a tropical storm in the far eastern Atlantic, east of 30W, for one day. It was named based on a new satellite classification technique that was not available 20 years ago called the Objective Dvorak Technique. Furthermore, prior to the late 1980's,the National Hurricane Center did not have official responsibility for the Atlantic Ocean east of 30W. Storms that formed and died in that part of the Atlantic may not have made it into the official HURDAT database of Atlantic storms. Several of this season's storms were named based on data from the QuikSCAT satellite and other new measurement techniques that were not available 20 years ago.

Furthermore, the definition of what should be a named storm is subjective, and has changed depending upon who is director of the National Hurricane Center. In the 1980s, director Bob Sheets declared that subtropical storms were not to be given names. It was not until 2002 that subtropical storms were deemed worthy of names. This year's Subtropical Storm Andrea would not have been named in the 1980s. A borderline tropical depression/tropical storm will not get named until it holds together for a while. How long is a while? Back in the 1970s and 1980s under NHC directory Neil Frank, a storm sometimes had to stay at tropical storm strength for a full day, according to an interview published yesterday in the Houston Chronicle. Since three of this year's storms lasted a day or less, they would not have been named under his tenure at NHC. A borderline storm is more likely to get named if it is close to land, but none of the three short-lived storms (Jerry, Chantal, and Melissa) threatened land.

All of these uncertainties in storm naming makes it very difficult to determine if climate change is causing an increase in the number of named storms in the Atlantic. A "best track" committee is working its way through all the Atlantic hurricane records to standardize the data, but this effort will take many years.

Why did the pre-season hurricane forecasts do so poorly?
In June, forecasters gave several reasons to expect a very active season in 2007:

1) A continuation of conditions since 1995 that have put us in an active hurricane period (in particular, the fact that sea surface temperatures in the Atlantic Main Development Region for hurricanes were about 0.6° C above normal.

2) The strong likelihood of either neutral or La Nina conditions in the tropical Pacific Ocean, leading to average to below average wind shear conditions.

Well, La Nina conditions did develop, and wind shear gradually declined during the season. Wind shear was slightly above average in August, near average in September, and below average in October over the main development region for hurricane formation. However, sea surface temperatures declined to near average levels by July and August, thanks to a major incursion of African dust. According to the excellent write up of this hurricane season's activity posted by Phil Klotzbach and Bill Gray, 2007 was the dustiest year over the tropical Atlantic since 1999. All this dust acted to block sunlight from reaching the ocean surface, and sea surface temperatures were not able to maintain their above average state. We don't have the ability to predict major dust outbreaks from Africa more than a few days in advance, and this inability will continue to confound efforts at seasonal hurricane prediction for years to come.

NPR interview cancelled
I was supposed to be featured on the National Public Radio show "Day to Day" today, but that interview got canceled at the last minute.

Jeff Masters

Updated: 4:32 PM GMT en Noviembre 30, 2007

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Antarctic iceberg sinks cruise ship

By: JeffMasters, 3:39 PM GMT en Noviembre 27, 2007

The November 2007 sinking of the cruise ship MS Explorer after it hit an iceberg in Antarctic waters is a reminder that the Antarctic is a dangerous place to sail. Ever since British explorer Ernest Shackleton's ship Endurance met its end when it become trapped and crushed in pack ice near Antarctica, the Antarctic waters have been a notoriously dangerous place for boats. For those of you unfamiliar with the story of Shackleton's ill-fated expedition, I highly recommend a reading of The Endurance: Shackleton's Legendary Antarctic Expedition. The book details the most mind-blowing tale of survival and courage I have ever read. Shackleton's phenomenal leadership skills saved the lives of all of his men. Shackleton refused to sleep for over 30 consecutive days while leading his men in an arduous months-long trek over the treacherous Antarctic sea ice. His voyage to find help using an open boat in winter on the storm-tossed Scotia Sea may rank as the greatest navigation feat of all time.


Figure 1. Antarctic sea ice (purple colors) at the time the MS Explorer hit an iceberg and sank. Summer is approaching in the Southern Hemisphere, leading to melting and break up of the sea ice and plenty of icebergs. Image credit: University of Illinois Cryosphere Today.

Why talk about Antarctic sea ice?
You hear a lot of talk about Arctic sea ice, but not about Antarctic sea ice. That's because Antarctic sea ice is relatively unimportant to the Earth's climate. Antarctica is a huge continent that rises thousands of feet above the ocean. It holds about 90% of the world's fresh water, locked up in its massive ice cap. The presence of such a titanic block of ice at the bottom of the world completely dominates the weather and climate of the region, and the year-to-year fluctuations of sea ice don't have a lot of impact on temperatures there.

The other reason to ignore Antarctic sea ice is that it hasn't changed much over the historical record. A look at the sea ice coverage since 1978 (Figure 2) shows very little change. Climate skeptics have pointed out that Antarctic sea ice has been near its maximum area the past few winters. However, this is not considered statistically significant, and there is no overall trend apparent in the data.

However, Antarctic sea ice may be important because of its ability to insulate and buttress glaciers and semi-permanent ice shelves along the coast. Recent melting of sea ice due to warming temperatures along the Antarctic Peninsula allowed warming ocean waters to penetrate close to shore, triggering the collapse of the Larsen B Ice Shelf in 2002. This Rhode Island-sized chunk of ice had been around thousands of years, and disintegrated in just three days. Any decline of Antarctic sea ice in coming decades might cause a speedier retreat of the continent's glaciers and ice shelves.


Figure 2. Antarctic sea ice area as observed via satellite since 1978. The maximum area in winter has ranged between 14-16 million square kilometers, about the same amount of ocean that the Arctic ice covers in winter. However, the Antarctic sea ice almost entirely melts away in summer, something the Arctic sea ice does not do (yet). Image credit: University of Illinois Cryosphere Today.

Antarctic cooling
What is significant is the fact that most of Antarctica cooled in recent decades (Figure 3). For example, the surface temperature at the South Pole cooled 0.05° C between 1980 and 1999 (Kwok and Comiso, 2002). However, the majority of Antarctica has shown no statistically significant warming over the past 50 years (Turner et al., 2005)--the cooling has just been over the past 25-30 years. In the period 2004-2007, much of the Antarctic warmed (Figure 4). Why did Antarctica cool between 1982 and 2004 if there was global warming going on?

Well, the globe, on average, has warmed about 1.1° F (0.65° C) in the 50 years ending in 2005 (IPCC, 2007). Given that there is a lot of natural variability in the climate, it should be expected that some areas of the globe would not see warming, given the relatively modest magnitude of global warming thus far.

Figure 3. Antarctic surface temperatures as observed via AHVRR satellite measurements between 1982 and 2004. Much of Antarctica cooled during this period. Image credit: IPCC The Physical Science Basis, Figure 3.32.


Figure 4. Antarctic surface temperatures as observed via AHVRR satellite measurements between 1981 and 2007. Note that the cooling trend observed from 1982-2004 has reversed, thanks to warming in the past few years. Image credit: NASA

In addition, the weather of the Antarctic is dominated by a strong band of westerly winds that blow around the pole. This circumpolar vortex extends from the surface to the stratosphere, and can attain very high wind speeds, thanks to the absence of large land masses to slow it down. This vortex tends to isolate Antarctica from the rest of the globe, keeping global warming from influencing Antarctica weather, and allowing the surface to cool. The Antarctic Peninsula, which sticks out from Antarctica towards South America, frequently lies outside the vortex. This has allowed the peninsula to warm significantly, compared to the rest of Antarctica (Figures 3 and 4). The Antarctic circumpolar vortex has strengthened in the past 25-30 years, forming an even stronger barrier than usual. Tree ring records (Jones and Widman, 2004) suggest that the circumpolar vortex has shown similar strengthening in the past, so the current cooling trend in Antarctica may be partly a natural cycle.

Another possibility, favored by climate modelers, is that the strengthening of the circumpolar vortex and recent cooling in Antarctica are primarily due to a combination of the recent increase in greenhouse gases and the opening of the Antarctic ozone hole. The ozone hole opened up at about the same time as the recent cooling began. Ozone absorbs UV radiation which heats the atmosphere around it, so the absence of ozone has led to cooling in the stratosphere over Antarctica. This cooling has been about 10° C in October-November since 1985 (Thompson and Solomon, 2002), and has acted to intensify the circumpolar vortex, leading to surface cooling. If the climate modelers are right, the circumpolar vortex will weaken as the ozone hole diminishes in coming decades. This will allow the Antarctic to begin warming with the rest of the globe.

References and resources

Intergovernmental Panel on Climate Change (IPCC), 2007, The Physical Science Basis.

Jones, J.M., and M. Widman, "Atmospheric science: Early peak in Antarctic oscillation index," Nature 432, 290-291 (18 November 2004) | doi:10.1038/432290b; Published online 17 November 2004.

Kwok, R., and J.C. Comiso, "Spatial patterns of variability in Antarctic surface temperature: Connections to the Southern Hemisphere Annular Mode and the Southern Oscillation", GEOPHYSICAL RESEARCH LETTERS, VOL. 29, NO. 14, 10.1029/2002GL015415, 2002.

Thompson, D.W.J., and S. Solomon, "Interpretation of Recent Southern Hemisphere Climate Change", Science 3 May 2002: Vol. 296. no. 5569, pp. 895 - 899 DOI: 10.1126/science.1069270.

Turner, J. et al., 2005, "Antarctic climate change during the last 50 years", International Journal of Climatology, Volume 25, Issue 3, pp 279-294.

Arctic sea ice

"Antarctic cooling, global warming?" RealClimate.org post, 3 December 2004.

Jeff Masters

Updated: 8:00 PM GMT en Agosto 16, 2011

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Giving thanks to the Hurricane Hunters and QuikSCAT scientists

By: JeffMasters, 7:54 PM GMT en Noviembre 21, 2007

Everyone knows that flying into hurricanes is dangerous work. The NOAA Hurricane Hunter aircraft have flown a number of dangerous flights over the years, most recently in Hurricane Felix on September 2 this year. NOAA P-3 aircraft N42RF (affectionately called Kermit), penetrated a rapidly intensifying Hurricane Felix as it approached Category 5 intensity. The aircraft hit four G's of acceleration in both the up and down directions in Felix's eyewall. Regulations require a flight to be aborted at that level of turbulence, and Kermit returned to base. A detailed inspection of the aircraft the next day revealed no damage, and Kermit returned to service for the remainder of hurricane season.


Figure 1. A NOAA P-3 refuels in Cold Bay, Alaska (left) on its way to the Aleutian Islands to fly a mission in the 1987 Alaska Storms Program. Right: The two NOAA P-3's get de-iced at Brunswick Naval Air Station, Maine, as they prepare for a mission into a 'Noreaster during the Experiment on Rapidly Intensifying Cyclones over the Atlantic (ERICA) in 1989. Both photos taken by yours truly.

What is less appreciated is that these aircraft fly research missions into dangerous weather conditions year-round and world-wide, and some of the most dangerous flights have occurred far from the tropics. Earlier this year, Kermit experienced perhaps the most dangerous flight of its 31-year career. On February 9, the aircraft flew into an intense winter storm 500 miles east of Newfoundland. The mission was part of the Ocean Winds project, a study designed to test the accuracy of QuikSCAT satellite wind estimates in regions of high wind and heavy rain. Flying at 3,000 feet, the aircraft sampled the surface winds with its SFMR (Step Frequency Microwave Radiometer) and dropsondes. The flights were timed to coincide with an overhead pass of the QuikSCAT satellite, which also measured winds at the ocean surface. It was a bit of a rough ride, since the storm packed winds of 100-110 mph at flight level. Sea spray kicked up by the powerful winds reached all the way to flight level, coating the windshield with a thick white coating of salt. The windshield washer failed, leaving the windshield partially opaque. It was an unusually dry winter storm, and the rain showers needed to rinse the windshield clean were difficult to find.


Figure 2. QuikSCAT wind profile of the ocean surface at 21:22 GMT February 9, 2007, just before Kermit headed back to St. John's, Newfoundland.

After a successful 4-hour flight, the aircraft dropped its final dropsonde, and turned north to complete its final sampling run. Suddenly, crew members observed flames coming from the #3 engine, accompanied by an audible popping sound. "Fire on #3, flames, flames, flames!" came the cry over the on-board intercom system. The pilots and flight engineers immediately began an emergency shut down of the #3 engine. As they worked to shut down the engine, the ominous call, "Fire on #4!" came over the intercom. The pilot immediately began an emergency shut down of the #4 engine. With both engines on the right wing now shut down, the pilot cautiously ramped up power on the two engines on the left wing, turned the aircraft towards home base in St. Johns, Newfoundland, and attempted to climb. However, the aircraft was not able to climb on just two engines, and the pilot was forced to begin a gradual descent to 2600 feet. The pilot notified the crew to review their ditching placards, and word was send to air traffic control informing them of the emergency. Three tense minutes passed, as the crew attempted to figure out what had caused the multiple engine failures. Speculation centered on the unusually heavy accumulation of salt on the aircraft--but excessive salt had never been implicated in engine failures before. Then, the words they all dreaded, "Fire on #1!" burst out over the intercom. The flight engineer immediately pulled the emergency shutdown handle for the #1 engine, and Kermit began a 700 foot per minute descent towards the turbulent sea below.

The crew donned survival suits as the pilot issued a May-day distress call and prepared to ditch the aircraft. Beneath them, hurricane force winds blew over the night-shrouded North Atlantic waters. With waves easily reaching 20 feet, water temperatures near freezing, and 500 miles out at sea at night, prospects for survival were dim. Four minutes remained to restart one of the flamed-out engines, and the pilot called for an immediate restart of the #1 engine. As the flight engineer worked to comply, Kermit passed through a brief rain shower that washed considerable salt from the aircraft. The attempt to restart the #1 engine succeeded, and Kermit pulled out of its descent just 800 feet above the waves--one minute from impact.

The crew now worked to restart the failed #3 and #4 engines, while the plane slowly climbed away from the ocean surface. As they headed towards Newfoundland, the Canadian Air Force launched a search and rescue C-130 aircraft from Nova Scotia to intercept Kermit. Crews on the Hibernia and Terra Nova oil rigs located east of Newfoundland were alerted of the emergency, and stood by to help if necessary. Kermit's navigator continuously plotted vectors to the oil rigs at they flew home, in case a ditch near one of the rigs became necessary.

As they continued westward, the crew successfully restarted both the #3 and #4 engines, but at reduced power. Kermit climbed to a more comfortable altitude of 14,000 feet and made it uneventfully back to St. Johns. Fortunately, the engines were undamaged and perfectly operational after the salt was washed out, and the data collected during the mission was saved. According to the detailed NOAA Mishap Investigation Report posted on Chris Mooney's excellent blog, "Post flight inspection of engines revealed significant white build up on intakes, first stage compressors, and CIP probes of all four engines. Subjectively, the #2 engine appeared to be the worst coated of all engines. Aircraft fuselage and windows were also heavily coated." Salt build-up on the engines was determined to be the cause of the incident. The unusually dry nature of the storm prevented the salt from being washed off, and was probably part of the reason the engines failed on this flight, and not on previous flights.

I asked Dr. Jim McFadden, project manager of the Ocean Winds project, what happened. He was on the flight, and responded:

This event stumped everyone including the experts who spend a life-time studying sea salt and aerosols in the marine boundary layer. Six previous flights in similar conditions had resulted in nothing like this. But this one was different. It was flown over an ocean warmed by the Gulf Stream in a dry slot of cold Canadian air. Somehow that combination was the key to what could have been a disastrous flight. Fortunately, quick thinking and the flawless action of the crew brought about by excellent training got us home safely.

Last week in Washington D.C., the crew of Kermit was honored with the Department of Commerce's Gold Medal for successfully bringing home the aircraft. The crew members from NOAA's Aircraft Operations Center who were on the flight were:

LCDR Mark Nelson
LCDR Carl Newman
Joseph Klippel
LCDR Peter Siegel
LCDR Joseph Bishop
Tom Shepherd
James Barr
Terry Lynch
William Olney
James McFadden

QuikSCAT scientists Paul Chang and Rob Contreras were also present on the flight.

Separate Department of Commerce Gold and Silver Medals were also awarded last week for scientists involved in leading NOAA's operational use of NASA's QuikSCAT satellite to produce more accurate forecasts and warnings of marine and coastal weather:

Paul Chang
Hugh Cobb III (NWS)
Roger Edson (NWS)
James Franklin (NHC)
Richard Knabb (NHC)
Eugene Legg
Kevin Schrab (NWS)
Joseph Sienkiewicz (NWS)

A Gold Medal is defined as distinguished performance characterized by extraordinary, notable or prestigious contributions that impact the mission of the Department and/or one operating unit and which reflect favorably on the Department. Congratulations to all the awardees, and thanks for all that you do!

Jeff Masters

Aviation

Updated: 11:51 PM GMT en Agosto 15, 2011

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Atlantic hurricane season probably over; Cyclone Sidr's death toll tops 3,000

By: JeffMasters, 2:24 PM GMT en Noviembre 19, 2007

The Atlantic hurricane season officially ends on November 30, but unofficially, it is probably over. While ocean temperatures are still plenty warm to support tropical cyclone formation in the Caribbean and the Bahamas, wind shear has become prohibitive across the entire tropical Atlantic, and is forecast to remain so until early December. It is possible wind shear will fall low enough over the mid-Atlantic in early December to support tropical storm formation. Any such storm would be far out at sea, and not threaten any land areas. Ocean temperatures are continuing to cool, though, and I put the odds of such a development at 20%. In the recent active Atlantic hurricane period that began in 1995, five of the twelve years have had a named storm form after November 18. With the exception of Tropical Storm Odette of December 2003, none of these storms hit land. Odette hit the Dominican Republic as a 50 mph tropical storm, and triggered flash floods that killed eight people. Late season storms typically form in the Western Caribbean or in the open Atlantic (Figure 1). Due to the frequent number of strong troughs of low pressure marching across the Atlantic this time of year, most tropical storms move north or northeast as soon as they form.


Figure 1. Path of all Atlantic named storms that formed between November 16 and 30, 1851-2006.

Tropical Cyclone Sidr's death toll at 3,000 and rising
Tropical Cyclone Sidr's death toll has risen above 3,000, making the storm the deadliest tropical cyclone the world has seen since Hurricane Mitch hit Honduras in 1998, killing over 9,000 people. The Red Crescent aid agency is estimating that Sidr's toll could reach 5,000-10,000, based on their experience with previous cyclones in Bangladesh. Thousands of people are still missing, and communications to many hard-hit outlying islands remain difficult.

Landmark IPCC report issued
The Nobel Prize-winning Intergovernmental Panel on Climate Change (IPCC) released their final "Synthesis Report" Saturday. This massive effort, repeated just once every seven years by 2,000 of the world's top climate scientists, summarizes the current state of scientific knowledge on climate change, the likely impacts, and options for how to respond. All literate citizens of the world should at least skim the 23-page report. For those of you unwilling to do so, I'll give you a 4-sentence summary:

Human-caused climate change is very likely already occurring, and will get much more significant over the coming decades. While some regions will experience benefits, most regions will experience costly and dangerous climate change. Developing nations will suffer the most. Strong action to reduce greenhouse gas emissions by 2015 is needed to prevent the worst impacts.

Jeff Masters

Updated: 2:30 PM GMT en Noviembre 19, 2007

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Bangladesh reeling from Cyclone Sidr; Landmark climate change report issued today

By: JeffMasters, 6:01 PM GMT en Noviembre 17, 2007

Tropical Cyclone Sidr has left immense devastation and suffering in its wake, after the Category 4 storm smashed ashore in Bangladesh with sustained winds near 150 mph. At least 2,000 people are dead, 5,000 injured, and over three million homeless. The cyclone's winds and storm surge of at least 20 feet destroyed over 273,000 buildings and killed over 242,000 livestock. A nation-wide power outage continues in Bangladesh, making communications difficult with the hard-hit areas.


Figure 1. Population density map of Bangladesh for regions less than 10 meters in elevation (red areas) and higher than 10 meters (green areas). The path of Tropical Cyclone Sidr took it inland over the Sundarbans Forest, the least populated region of the coast. However, the more heavily populated provinces just to the right of the Forest, Barguna and Patuakhali, received a storm surge of 10-20 feet. A storm surge of 20 feet was reported at Charkhali, at the head of a narrow estuary connected to the ocean. Image credit: CIESEN, Columbia University.

Sidr's death toll
The death toll from Sidr will go much higher, making the storm the deadliest tropical cyclone the world has seen since Hurricane Mitch of 1998. Mitch dumped up to 30 inches of rain on Honduras, triggering flash floods that killed over 9,000 people. I don't think Sidr's death toll will surpass Mitch's, as the government of Bangladesh was quite successful getting the warning out and evacuating those who would go. The days when a cyclone will kill tens of thousand of Bangladeshis, such as occurred when 140,000 died in the 1991 Bangladesh Cyclone, are probably done. Bangladesh holds ten of the top twenty spots on the list of the world's deadliest tropical cyclones of all time.

Landmark IPCC report issued today
The Nobel Prize-winning Intergovernmental Panel on Climate Change (IPCC) released their final "Synthesis Report" today. This massive effort, repeated just once every seven years, summarizes the current state of scientific knowledge on climate change, the likely impacts, and options for how to respond. All literate citizens of the world should read the 23-page report.

Jeff Masters

Updated: 6:13 PM GMT en Noviembre 17, 2007

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Tropical Cyclone Sidr devastates Bangladesh

By: JeffMasters, 3:22 PM GMT en Noviembre 16, 2007

Tropical Cyclone Sidr has devastated the low-lying nation of Bangladesh. At least 496 are dead, 540 missing, and thousands injured. The cyclone's 150 mph winds and storm surge of at least 20 feet destroyed tens of thousands of buildings, and have left over 100,00 people homeless. A nation-wide power outage hit the country in the wake of Sidr, making communications difficult. Power is only now beginning to be restored to some regions. Most of the reported deaths were from collapsed buildings and flying debris hurled by the Category 4 cyclone, which hit the country at 9pm local time Thursday night. The storm moved northeastward across the country, and has now dissipated in the foothills of the Himalaya Mountains.


Figure 1. Population density map of Bangladesh for regions less than 10 meters in elevation (red areas) and higher than 10 meters (green areas). The path of Tropical Cyclone Sidr took it inland over the Sundarbans Forest, the least populated region of the coast. However, the more heavily populated provinces just to the right of the Forest, Barguna and Patuakhali, likely received a storm surge of 10-20 feet. Sidr passed near the city of Barisal, where sustained winds of 92 mph were measured at midnight local time. The deadliest cyclones for Bangladesh have always taken a more easterly track, near the city of Chittagong. Image credit: CIESEN, Columbia University. Thanks go to Margie Kieper for finding the image.

Sidr's storm surge
Storm surge is usually the biggest killer in Bangladesh cyclones, and was responsible for the vast majority of the 140,000 people killed in the 1991 Bangladesh Cyclone. This storm struck eastern Bangladesh as a Category 5 cyclone--the only Category 5 cyclone on record to hit the country. The triangular shape of Bengal Bay funnels high surges into the apex of the triangle where Bangladesh sits, and the shallow bottom of the bay allows extraordinarily high storm surges to pile up. The maximum storm surge from Sidr was probably 20-25 feet, and affected the regions near and to the right of where the eye made landfall. The eye fortunately came ashore in the Sundarbans Forest, the world's largest forest of mangrove trees. This region is the least populated coastal area in the country (Figure 1). Storm surge levels of 10-20 feet probably affected the provinces of Barguna and Paruakhali, which are more heavily populated. Undoubtedly, the storm surge killed many more people in these provinces, and Sidr's death toll will go much higher. However, Bangladesh has done a much better job providing shelters and evacuating people during cyclones since the 1991 storm. Over 650,000 people did evacuate from Sidr, and it is unlikely the death toll will put the storm on the list of the world's deadliest cyclones of all time. Bangladesh already holds ten of the top twenty spots on that list.

Jeff Masters

Updated: 3:29 PM GMT en Noviembre 16, 2007

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Cyclone Sidr slams into Bangladesh

By: JeffMasters, 3:34 PM GMT en Noviembre 15, 2007

Tropical Cyclone Sidr made landfall at 1430 GMT in western Bangladesh as a mighty Category 4 storm with 150 mph winds. Sidr is the second strongest cyclone to make landfall in Bangladesh since reliable record keeping began in 1877. The only stronger storm was the 1991 Bangladesh Cyclone, which struck eastern Bangladesh as a Category 5 cyclone. The 30 foot storm surge of that storm killed at least 140,000 people. Sidr is the Arabic word for the jujube tree.


Figure 1. Image of Tropical Cyclone Sidr as a Category 4 storm (928 mb) with 155 mph winds. Image taken at 4:57am EST 11/15/07. The cyclone made landfall at 1430 GMT in the Sundarbans Forest area of Bangladesh, just east of Calcutta, India. Image credit: Navy Research Lab.

Sidr's storm surge
The big killer in Bangladesh cyclones is the storm surge. The triangular shape of Bengal Bay funnels high surges into the apex of the triangle where Bangladesh sits, and the shallow bottom of the bay allows extraordinarily high storm surges to pile up. The maximum theoretical storm surge from a worst-case Category 5 cyclone is thought to be 41 feet in western Bangladesh (Islam, 2006). Sidr's maximum storm surge to the right of where the eye makes landfall is likely to be in the 20-25 foot range. Of critical importance is the timing of landfall with respect to high tide, since there is a 1.5 meter (5 foot) difference between low and high tide in western Bangladesh. According to mobilegeographics.com, high tide is at approximately 1am local time tonight, and Sidr made landfall about halfway between low and high tide. Thus, Bangladesh did have a little luck, as the storm tide could have been about 2-3 feet higher had Sidr hit at high tide.

The coast in western Bangladesh has the Sundarbans Forest, the world's largest forest of mangrove trees. This region is the least populated coastal area in the country, and has been part of a major reforestation effort in recent years. The portion of coast likely to receive the highest storm surge levels of 20-25 feet is virtually unpopulated. However, storm surge levels of 10-20 feet are still likely to affect areas with a population of at least a million, to the east of the Sundarbans forest, and inland from the forest. The last major cyclone to hit western Bangladesh occurred in November 1988. This Category 3 cyclone with 125 mph winds had a 5-10 foot storm surge, and killed 2,000 people.

Hurricane shelters in Bangladesh
Since the Great Bhola Cyclone of 1970, a Category 4 cyclone that brought a storm surge of up to 27 feet and killed an estimated 350,000-550,000 people, Bangladesh embarked on program to build concrete cyclone shelters (Figure 2). After the 1991 cyclone, this process accelerated, thanks in part to foreign assistance. Bangladesh now has over 2500 multi-purpose cyclone shelters that can also be used as primary schools. The warning system in Bangladesh is fairly effective at notifying the population of an approaching cyclone, but many residents choose not to evacuate to the shelters, since most of them are in poor condition with minimum or no maintenance at all (Karim, 2001). In any case, these shelters can accommodate less than 3% of the population of western Bangladesh (Islam, 2006).


Figure 2. A Bangladesh cyclone shelter built after the devastating 1970 cyclone. Image credit: Harry M. Jol, professor at University of Wisconsin, Eau Claire.

The Bangladesh newspaper The Daily Star is already reporting that 300 fishing boats have sunk in Sidr, with 1,000 fishermen missing. While I don't expect we'll see anything approaching the 1991 cyclone with its death toll of 140,000, since Sidr is hitting a relarively unpopulated region of the coast, the storm has the potential to kill several thousand people in Bangladesh. Also of concern is India. The eastern portion of the Calcutta metropolis will receive winds near hurricane force, and these winds could cause major destruction of poorly built housing. Flash flooding from heavy rains could also affect both India and Bangladesh. It's a bad night to be in Bangladesh.

Links to follow for Sidr
Dhaka, Bangladesh current conditions
Calcutta, India current conditions

References

Islam, T., "Integrated Approach to Cyclone Wind Analysis and disaster planning for the Benladesh coast," Ph.D. Dissertation, Texas Tech University, December 2006.

Karim, N., (1999) Options for cyclone protection: Bangladesh context".

Paul, A., and M. Rahman, "Cyclone Mitigation Perspectives in the Islands of Bangladesh: A Case of Sandwip and Hatia Islands", Coastal Management, 34, Issue 2 April 2006, p, pp 199-215.

Jeff Masters

Updated: 4:19 PM GMT en Noviembre 15, 2007

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Extremely dangerous Cyclone Sidr bears down on Bangladesh and India

By: JeffMasters, 2:43 PM GMT en Noviembre 14, 2007

Tropical Cyclone Sidr, a powerful Category 4 storm with 140 mph winds, is bearing down on the densely populated coasts of Bangladesh and India. Landfall is expected along a low-lying stretch of coast just east of Calcutta (Kolkata), India in just 36 hours. Sidr (the Arabic word for the the jujube tree) is only the second major (Category 3 or higher) tropical cyclone to affect the Bay of Bengal this decade. The other was Tropical Cyclone Mala, which hit Myanmar as a Category 3 storm on April 28, 2006, killing 22 people.


Figure 1. Image of Tropical Cyclone Sidr as a Category 4 storm (933 mb) taken at 2:47am EST 11/14/07. Image credit: Navy Research Lab.

Sidr weakened briefly yesterday, as its inner eyewall collapsed and was replaced by a new outer eyewall with a larger diameter. Now that this process is complete, Sidr has taken advantage of the low wind shear and high heat content oceanic waters it find itself over, and was intensified. As the storm continues northwards over the next 24 hours, the storm should be able to maintain its intensity. However, in the 12 hours prior to landfall, there will be a sharp increase in wind shear associated with a trough of low pressure. Ocean heat content will be on the decline as well, and the best guess is that Sidr will be a Category 1 or 2 cyclone when it hits land.


Figure 2.Deadliest tropical cyclones of world history.

A Category 1 or 2 cyclone hitting the low-lying, densely populated coasts of Bangladesh could still be devastating. The triangular shape of the Bay of Bengal acts to funnel storm surge waters into Bangladesh, and the very shallow bottom of the bay allows the surge to pile up to very high heights. A list of the 13 deadliest cyclones in world history (Figure 2) shows that nine of these have occurred in the Bay of Bengal. The big killer in all of these cyclones was the storm surge. The only known cyclone of Category 5 strength to hit Bangladesh, the April 1991 cyclone, brought a 30 foot storm surge to the coast near Chittagong. Surge height up to 41 feet are possible along some regions of the coast (Figure 3).


Figure 3.Maximum surge height along Bangladesh's Bay of Bengal coast as computed by Islam (2006).

The big question is, how much of the storm surge that Sidr is currently piling up with its Category 4 winds will make it to the coast, if the expected weakening occurs? We know from our experience with Hurricane Katrina that a weakened Category 3 hurricane at landfall can still push a storm surge characteristic of a Category 5 storm to the coast. This occurs because once a hurricane sets a large mass of water spinning, the angular momentum of that spinning water takes a long time to relax. The ocean carries the memory of how strong a hurricane was to the coast, in the form of a higher storm surge. Thus, I would expect a storm surge at least one category higher than what one might expect based on its landfall strength. One positive note is that Sidr is a much smaller storm than Katrina. Hurricane force winds extend outwards about 60 miles from Sidr's center, which is half of what Katrina's winds did. Thus, Katrina's hurricane force winds blew over an area of ocean four times greater than Sidr's.

methaz.org is currently predicting that a storm surge of 12-15 feet will affect the Bangladesh coast.

Links to watch:
Calcutta (Kolkata), India
Barisal, Bangladesh
Cox's Bazaar, Bangladesh

References:

Islam, T., "Integrated Approach to Cyclone Wind Analysis and disaster planning for the Bangladesh coast," Ph.D. Dissertation, Texas Tech University, December 2006.

I'll have an update Thursday.

Jeff Masters

Updated: 3:12 AM GMT en Noviembre 15, 2007

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Black Sea storm causes ecological disaster; powerful Bay of Bengal cyclone forming

By: JeffMasters, 3:25 PM GMT en Noviembre 12, 2007

At least five ships sunk and five others ran aground yesterday during a fierce storm that swept through the Black Sea, by Russia and the Ukraine. Five sailors drowned and as many as 17 others are missing. The Volganeft-139, an oil tanker loaded with nearly 1.3 million gallons of fuel oil, sank in the Kerch Strait between the Black Sea and the Sea of Azov, dumping over 1/2 million gallons of fuel into the water. The oil spill is a major environmental disaster for the area, and will foul local shores for years to come. The spill is about 1/20 the size of the massive Exxon Valdez oil spill of 1989.


Figure 1. Visible image from the NOAA-18 polar orbiting satellite from Saturday, November 10, 2007, at 11:21 GMT. An "L" marks the center of the developing storm that would move over the Black Sea and sink or ground ten ships. The storm formed at the tail end of a cold front to its north. Image credit: University of Bern, Switzerland.

The storm that sank these ships was an unusually powerful one for the Black Sea. The storm formed over the Mediterranean Sea along the tail end of a very strong cold front. This front was the same cold front that pushed through the North Sea on Friday, bringing winds near hurricane force, flooding in southeast England, and a storm surge over 10 feet high to the coast of the Netherlands. The new storm fed off the relatively warm waters of the Mediterranean and pushed eastward across Greece and Turkey, intensifying to 980 mb as it struck the Ukraine's Crimean Peninsula late in the morning Sunday. Simperopol, Ukraine, on the tip of the Crimean Peninsula, measured sustained winds of 54 mph, gusting to 72 mph, on Sunday afternoon. The pressure bottomed out at 980 mb. Kerch, Ukraine, on the west side of Kerch Strait, recorded sustained winds of 45 mph and a minimum pressure of 988 mb as the storm blew through. On the other side of the strait, in Anapa, Russia, sustained winds of 47 mph, gusting to 65 mph were observed. Waves up to 18 feet high buffeted the waters in the Kerch Strait. This was too much for the Volganeft-139, which was designed for river travel.

The enclosed nature of the Black Sea can produce very steep waves. According to Holquist et al. (2002), steep, short-period waves can be particularly hazardous to large ships, especially when the waves exceed 5 meters (16 feet) in height. The height of waves depends on the wind speed and the fetch or distance over which the wind blows. Also important is the degree atmospheric stability near the surface. A warm ocean with very cold air aloft will produce an unstable atmosphere with very tall turbulent eddies that will mix down the stronger winds that occur aloft. This instability peaks in November, when the air-sea temperature difference is at its greatest.

References
Hultquist, T.R. M.R. Dutter, and D.J. Schwab, "Reexamination of the 9–10 November 1975 “Edmund Fitzgerald” Storm Using Today’s Technology", Bulletin of the American Meteorological Society, May 2006.

The NASA Natural Hazards team has posted a nice satellite image and description of the storm.

Tropical Update
None of the reliable computer forecast models are predicting tropical cyclone formation in the Atlantic for the next seven days. I'll have a complete analysis of the outlook for the remaining 2 1/2 weeks of hurricane season later this week.


Figure 2. Tropical Cyclone Sidr at 5:30am EST 11/12/07. Image credit: Navy Research Lab, Monterey.

Tropical Cyclone Sidr is headed northwards towards a landfall in Bangladesh or India late this week, and may intensify into a Category 2 or higher storm. The Bay of Bengal has seen the world's deadliest tropical cyclones, and November is one of the region's most dangerous months. On November 12-13, 1970, a Category 4 cyclone struck Bangladesh, causing the greatest tropical cyclone disaster in world history. An estimated 350,000-550,000 people died when a devastating 34-foot storm surge funneled northwards through the Bay of Bengal into Bangladesh. The path of Tropical Cyclone Sidr beyond Wednesday is highly uncertain, with the NOGAPS and ECMWF models taking the storm northwards over a region of high oceanic heat content and into Bangladesh. The GFS model turns Sidr westwards, over a region of low oceanic heat content, into the east coast of India. Wind shear is about 10 knots over the storm, and is expected to remain 10 knots or below for the next three days. Recent satellite observations suggest that Sidr is already of hurricane strength, and may be intensifying rapidly.

Jeff Masters

Winter Weather

Updated: 7:09 PM GMT en Enero 05, 2012

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North Sea storm spares England and the Netherlands

By: JeffMasters, 1:35 PM GMT en Noviembre 09, 2007

A massive fall storm over Europe's North Sea generated winds near hurricane force last night that pushed a dangerous storm surge near 1.5 meters (4.65 feet) in height to the southeastern English coast this morning. The storm surge was much lower than originally feared, due in part to the fact it did not hit at high tide. The surge did breach sea defenses and caused some minor coastal flooding in England. It was feared that the storm might rival the great North Sea Flood of 1953 that breached the dikes in the Netherlands. Over 2,000 people died in northern Europe in that storm, mostly in the Netherlands. While today's storm did not approach the 1953 storm in severity, it did bring the highest storm surge seen in the past 20 years to the North Sea. The massive flood gates that protect the Dutch port of Rotterdam were closed for the first time since they were constructed in the 1990s. From early media accounts, the gates did their job admirably, protecting the Netherlands from inundation. Water levels reached 3.16 meters above mean sea level in the southern Netherlands, and 3.40 meters above sea level in the northern Netherlands, with no flooding reported. The floods of 1953 saw Dutch waters rise to 3.85 meters (12.6 ft) above sea level. Today's storm was not the remains of Hurricane Noel, which is currently over northern Canada.


Figure 1. Visible satellite image of Europe from 1322 GMT November 8, 2007. A powerful 975 mb low pressure system centered north of England ("L" on the image) was pushing a strong cold front southwards towards Western Europe. Image credit: University of Bern, Switzerland.


Figure 2. Forecast waves heights at 6am Greenwich time, Friday November 9, 2007, as predicted by NOAA's Wavewatch III model.

Tropical update
An area of disturbed weather over the extreme southern Caribbean, near Panama, is under about 20 knots of wind shear. The computer forecast models are predicting that some development of this region may occur by Sunday, when wind shear is expected to fall below 20 knots. However, the models are less keen on this prospect than yesterday. Any system that might form is expected to move westward and affect Costa Rica and Nicaragua.

I'll have an update Monday morning, unless there's some new development this weekend.

Jeff Masters

Winter Weather

Updated: 7:09 PM GMT en Enero 05, 2012

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Huge North Sea storm threatens England and the Netherlands with serious flooding

By: JeffMasters, 1:14 AM GMT en Noviembre 09, 2007

A massive fall storm over Europe's North Sea is generating winds near hurricane force that is expected to push a dangerous storm surge over 3 meters (10 feet) in height to the coast Friday morning. The storm is being compared to the great North Sea Flood of 1953 that pushed a 5.6 meter storm surge that breached the dikes in the Netherlands. Over 2,000 people died in northern Europe in that storm, mostly in the Netherlands. While today's storm will not approach the 1953 storm in severity, the storm may generate a once in 20 years type of flooding event. Thousands of people have been ordered to evacuate in the United Kingdom, and the massive flood gates that protect the Dutch port of Rotterdam are being closed for the first time since they were constructed in the 1990s. The worst of the storm surge is expected to hit the Netherlands near 7am local time Friday.


Figure 1. Visible satellite image of Europe from 1322 GMT November 8, 2007. A powerful low pressure system centered north of England ("L" on the image) was pushing a strong cold front southwards towards Western Europe. Image credit: University of Bern, Switzerland.

Oil platform 62114 in the North Sea off the coast of Scotland reported sustained winds of 55 knots (64 mph) at 2pm local time, and seas up to 26 feet were observed at oil platform 63110. An oil platform close to the coast of the Netherlands (62145) reported winds of 40 mph with 16 foot waves this evening. The latest QuikSCAT pass this evening showed a large area of winds over 50 knots in the North Sea. These winds are pushing a strong cold front southwards over Western Europe (Figure 1).


Figure 2. Forecast waves heights at 6am Greenwich time, Friday November 9, 2007, as predicted by NOAA's Wavewatch III model.

I'll have an update on the storm Friday morning.

Jeff Masters

Winter Weather

Updated: 7:09 PM GMT en Enero 05, 2012

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Quiet Atlantic; possible development near Nicaragua this weekend

By: JeffMasters, 3:21 PM GMT en Noviembre 08, 2007

The Atlantic is currently quiet, but all four reliable models are forecasting a tropical depression may form in the extreme southern Caribbean on Saturday or Sunday. The storm is expected to move westward, and hit southern Nicaragua on Monday. The extreme southern Caribbean is the only region of the tropical Atlantic with low enough wind shear to support tropical cyclone formation in the coming week. Residents of Costa Rica and Nicaragua should anticipate the possibility of heavy rains this weekend, and a tropical disturbance is already bringing heavy rains to these countries today. Wind shear is expected to be 20-40 knots for the next 48 hours, which should prevent any development until Saturday.

Wunderblogger Mike Theiss has posted his chase account of 'Noreaster Noel in Nova Scotia. The 100+ foot high wave he saw was quite impressive!

Jeff Masters

Updated: 3:21 PM GMT en Noviembre 08, 2007

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Quiet in the Atlantic

By: JeffMasters, 1:48 PM GMT en Noviembre 07, 2007

A non-tropical "cut-off" low pressure system (92L) near 31N 32W, a few hundred miles southwest of the Azores Islands, has become more tropical. Satellite loops show thunderstorm activity near the center is trying to get organized, but this is being stymied by 30-40 knots of wind shear. Wind shear is expected to remain above 30 knots for the next two days. Sea Surface Temperatures are about 24° C under 92L, which is considerably cooler than the 26.5° usually needed to get a tropical cyclone going. The system is expected to turn northeast and move through the Azores Islands Friday, where SSTs are in the 21-22° C range. Due to the high wind shear and cool SSTs, development into a tropical cyclone is not likely.

Elsewhere in the Atlantic, none of the reliable computer forecast models are predicting formation of a tropical cyclone over the coming week. Is hurricane season over? I'll have a full analysis of the possibilities Wednesday or Thursday of next week. Right now, it appears that we will not have any more landfalling tropical storms.

Jeff Masters

Updated: 1:52 PM GMT en Noviembre 07, 2007

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Mexico's Katrina

By: JeffMasters, 3:22 PM GMT en Noviembre 06, 2007

While Hurricane Noel's deadly rampage through the Caribbean was making headlines last week, Mexico experienced one of the worst flooding disasters in its history. Rescue crews are still at work plucking thousands of stranded residents off of rooftops in the state of Tabasco. Over 80% of Tabasco was underwater, and flood waters reached up to residents' rooftops in the capital city of Villahermosa. Up to 900,000 people are homeless in the disaster, which Mexicans are calling their Hurricane Katrina. The number of people dead or missing now stands at 26, due to a new mudslide yesterday that overwhelmed a small village near Villahermosa.

The floods were spawned by heavy rains that fell from a cold front that stalled over the Gulf of Mexico between October 28 and November 1. Satellite estimates of the rainfall show that no more than 7 inches of rain fell over the region during the period, which seems like too little rain to cause the massive flooding observed. It is possible these satellite estimates are flawed. The official rain gauge in Villahermosa reported 2, 81, 7, 0, and 2 inches of rain during the days October 28-November 1, respectively. Presumably, the 81 inches of rain reported October 29 is due to floodwaters inundating the rain gauge. Villahermosa averages 13 inches of rain in a typical October. No new rains have fallen since November 1, and the flood waters are gradually receding.


Figure 1. Thick clouds cover Mexico's Tobasco state on October 29, 2007, due a cold front that stalled over the region. The area received up to 7 inches of rain over a 5-day period. Image credit: NASA.

Disturbance 92L in far eastern Atlantic not a threat
A non-tropical "cut-off" low pressure system near 31N 37W, a few hundred miles southwest of the Azores Islands, is showing signs of becoming more tropical. This system was designated "92L" by NHC this morning. Phase space diagrams from Bob Hart at Florida State University show that 92L started off as a classic extratropical storm that was asymmetrical with a cold core, but the storm has gotten more symmetrical and the core has warmed. Satellite loops show only limited thunderstorm activity near the center of circulation at present, though. Sea Surface Temperatures are about 24° C under 92L, and are considerably cooler than the 26.5° usually needed to get a tropical cyclone going. Wind shear is 30-40 knots, and is expected to stay above 30 knots for the next two days. These factors should keep the storm from developing. The system is expected to turn northeast and move through the Azores Islands Friday or Saturday.

Jeff Masters

Flood

Updated: 11:01 PM GMT en Agosto 16, 2011

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Noel is gone; Atlantic is quiet

By: JeffMasters, 2:23 PM GMT en Noviembre 05, 2007

All is quiet in the tropical Atlantic. The near-tropical depression that moved ashore last night over Nicaragua has dumped about 6 inches of rain over northeastern Nicaragua and Honduras. Disturbed weather continues in this region and over the adjacent ocean areas, but the activity has died down considerably since yesterday, and is not a threat to develop. None of the reliable computer models show any tropical cyclone development in the Atlantic over the next week. Wind shear is expected to be high over the entire tropical Atlantic, except for the extreme southern Caribbean near Nicaragua and Costa Rica.

'Noreaster Noel
'Noreaster Noel whipped up some very impressive winds and waves over the weekend, and I have a few more stats to share on the storm. For Canada, here are some of the peak wind reports:

St. Paul Island: 62 mph gusting to 79 mph
Hart Island: 51 mph gusting 75 mph
Halifax Airport (20 kilometers inland): 58 gusting 70 mph.
Grand Etang, Cape Breton: 63 gusting 89 mph, though this is partly a local phenomenon, caused by amplification by the topography of the Cape Breton Highlands.

The peak waves at the Georgian Bank buoy 44011 were 45.6 feet. These were 6 feet higher than those measured during the famed "Perfect Storm" of October 1991. Noel's waves were the highest recorded at the buoy since the on-line record begins in 1984.

Thanks go to Peter Watson for the wind stats and Margie Kieper for the wave stats.

Wunderphotographer Mike Theiss was in Nova Scotia for the storm, and plans on posting his usual fantastic photos later today or Tuesday.

Jeff Masters

Updated: 2:25 PM GMT en Noviembre 05, 2007

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'Noreaster Noel whips up high winds and huge waves

By: JeffMasters, 1:50 PM GMT en Noviembre 04, 2007

'Noreaster Noel whipped past New England Saturday, bringing coastal flooding, heavy rains up to four inches, and numerous reports of downed trees and power lines. The top wind gust in the U.S. was 89 mph at Barnstable on Cape Cod. The highest sustained winds were measured on Nantucket Island--56 mph, gusting to 72. The highest wind gusts in Maine were 64 mph measured at Brooklin and Cutler. Acadia National Park had one of the highest rain fall totals, 4.2 inches, and up to three inches of snow was recorded in northwestern Maine. At the storm's peak, 43,000 people lost power in Massachusetts.

Huge waves up to 34 feet high were measured in Halifax Harbor in Nova Scotia, and waves up to 46 feet high were measured at the Georgian Bank buoy midway between Cape Cod and Nova Scotia. Top winds in Nova Scotia were 50 mph, gusting to 62 mph, measured at Brier Island between 4am and 6am this morning. The 'Noreaster is over the Gulf of St. Lawrence this morning, with a central pressure of 970 mb and sustained winds near 50 mph. The storm knocked out power to over 150,000 people in Nova Scotia.


Figure 1. Rainfall estimate for the six hours ending at 4am EST Sunday, 11/04/07. Rainfall amounts up to 3 inches (75 mm) were observed in extreme northeastern Nicaragua. Image credit: Navy Research Lab, Monterey.

Near-tropical depression hits Nicaragua and Honduras
A region of disturbed weather that was the southern portion of Hurricane Noel's rainy regime acquired a spin of its own, almost became a tropical depression, and has now moved inland near the Nicaragua/Honduras border. This disturbance (91L) is generating rains of up to three inches every six hours (Figure 1). Total rain rain amounts of 5-10 are possible in Nicaragua and Honduras along the path of 91L, which could cause life-threatening flash floods and mudslides.

I'll have an update Monday morning.

Jeff Masters

Winter Weather

Updated: 7:09 PM GMT en Enero 05, 2012

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'Noreaster Noel pounds New England; new tropical depression may hit Nicaragua

By: JeffMasters, 3:59 PM GMT en Noviembre 03, 2007

Hurricane Noel is now 'Noreaster Noel, and wind and seas are steadily rising near New England and Nova Scotia. Sustained winds of 53 mph, gusting to 61 mph, were observed at Buzzard's Bay, Massachusetts at 1pm EDT, and winds at Nantucket Island were 43 mph, gusting to 53 mph. At 3am this morning, strong winds along North Carolina's Outer Banks pushed the sea over Highway 12 near Rodanthe, cutting off the islands from the mainland. Seas were 10-12 feet along North Carolina, and much higher in the open ocean--up to 37 feet at buoy 41048 a few hundred miles west of Bermuda. Waves up to 30 feet are expected to batter the shore of western Nova Scotia, where 'Noreaster Noel is expected to barrel ashore tonight. 'Noreaster Noel has already brought up to an inch of rain to eastern Long Island and coastal Massachusetts (Figure 2), and heavy rains of 4 inches will be common along the coast.


Figure 1. Visible satellite image of 'Noreaster Noel taken at 10:45am EDT 11/03/07. Disturbance 91L is visible at the bottom of the image. Image credit: NASA Goddard.


Noel's trail of destruction
Noel's death toll now stands at 127, with many more missing. The Dominican Republic suffered 82 deaths, Haiti 43, the Bahamas one, and Jamaica one. Noel is the deadliest storm this hurricane season.

Links to follow for 'Noreaster Noel
New England Marine weather and buoy reports
Long range radar out of Boston, MA
Google Maps interface, zoomed in on Nantucket, MA

Figure 2. Total rainfall from 'Noreaster Noel.


New tropical depression could form near Nicaragua
A region of disturbed weather that was the southern portion of Hurricane Noel's rainy regime has acquired a spin of its own, and appears to be organizing into a tropical depression. This disturbance has been labeled "91L" by NHC today. Wind shear is about 10 knots over 91L, and is expected to be 10-20 knots through Monday. This should allow the system enough time to organize into a tropical depression or weak tropical storm before it makes landfall over Nicaragua on Monday. Heavy rains will begin to affect northeastern Nicaragua tonight and spread into northeast Honduras on Sunday. Total rain amounts of 4-8 inches are likely by Tuesday. An Air Force Hurricane Hunter aircraft is scheduled to investigate 91L Sunday afternoon.

I'll have an update Sunday morning.

Jeff Masters

Hurricane

Updated: 7:09 PM GMT en Enero 05, 2012

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Noel the hurricane becomes Noel the 'Noreaster

By: JeffMasters, 1:59 PM GMT en Noviembre 02, 2007

Hurricane Noel pulled off a surprising burst of intensification last night despite 30 knots of wind shear. The storm's pressure dropped from 993 mb to 981 mb in just a few hours, and the winds cranked up to 80 mph. Noel is the first November hurricane in the Atlantic since Hurricane Michelle of 2001. Fortunately, Noel's intensification burst came after the storm had cleared the Bahama Islands, and wind damage was relatively minor in the islands. The latest Hurricane Hunter eye report at 8am EDT found the pressure holding steady at 981 mb, and weaker surface winds, 70-75 mph.

Noel the hurricane becomes Noel the 'Noreaster
Noel will brush Cape Hatteras, North Carolina, today, bringing winds near tropical storm force and a few rain bands. Strong northerly winds are expected to cause coastal flooding inside Pamlico Sound, with water levels 4-6 feet above normal. Winds at the Diamond Shoals buoy off the coast of Cape Hatteras were sustained at 40 mph, gusting to 47 mph, at 10am EDT. Seas were 15 feet, and 10-12 foot breakers are expected along the Outer Banks today. Noel has expanded significantly in size over the past 24 hours, and is bringing tropical storm force winds over a huge area of ocean (Figure 1). As Noel approaches New England on Saturday, the hurricane will make the transition to a powerful 'Noreaster, as cold air spills into the storm from the northwest. Noel's wind field is expected to expand farther, and the storm will maintain its intensity. Sustained winds of tropical storm force (39 mph) are likely along eastern Long Island and the coasts of Rhode Island, Massachusetts, New Hampshire, Maine, and Nova Scotia. The latest (06Z) runs of the GFDL and HWRF models intensify Noel to a 954 mb 'Noreaster, and bring sustained winds of hurricane force (75 mph) to Cape Cod and Nantucket. The ECMWF and NOGAPS models also bring Noel quite close to Cape Cod, and foresee a landfall near the Maine/Nova Scotia border. The UKMET and GFS models are farther east, bringing Noel to the western or central coast of Nova Scotia. Due to the wide wind field of Noel, both Massachusetts and Nova Scotia may see hurricane force winds. Due to the cold air invading Noel from the west, the western side of the storm will be the rainy side, and coastal Massachusetts can expect 2-6 inches of rain. About 1-3 inches are likely for Nova Scotia.


Figure 1. QuikSCAT image from 6:47am EDT Friday, 11/02/07. Can you find the hurricane?

Noel's trail of destruction
Noel's death toll now stands at 115, with many hard-hit rural areas yet to be heard from. The Dominican Republic suffered 73 deaths, Haiti 40, the Bahamas one, and Jamaica one. Noel is the deadliest storm this hurricane season. Hurricane Felix's official death toll was 101 people in Nicaragua and Honduras earlier this season (wikipedia puts this toll at 133). Additional rains of 1-2 inches are likely to fall in Haiti, eastern Cuba, and the eastern Bahamas today, due to Noel. Noel brought over 20 inches of rain to some of the Bahamas Islands, such as Rum Cay and San Salvador Island (Figure 2).


Figure 2. Satellite estimated rainfall totals for October 26-November 1, from the NASA TRMM satellite.

Links to follow for Noel
Satellite loop
North Carolina marine weather and buoy reports
Long range radar out of Cape Hatteras, NC
Google Maps interface, zoomed in on Cape Hatteras, NC

I'll have an update Saturday morning.

Jeff Masters

Hurricane

Updated: 7:10 PM GMT en Enero 05, 2012

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Noel to bring big winds to Massachusetts and Nova Scotia

By: JeffMasters, 7:39 PM GMT en Noviembre 01, 2007

Tropical Storm Noel is headed out to sea, and will clear the Bahama Islands early this evening. The latest report from the Hurricane Hunters at 1:17pm EDT found Noel at about the same strength--a pressure of 993 mb, and winds of 65 mph. Satellite imagery shows an impressive burst of thunderstorms on Noel's east side, and these thunderstorms dumped 5.5 inches of rain since midnight on Spanish Wells on Eleuthera Island, just northeast of Nassau. Wind gusts up to 50 mph have been observed at Foots Cay and 59 mph at Elbow Cay on Abaco Island this afternoon.

Big winds for Nova Scotia, Maine, and Massachusetts
The latest 12Z model runs have zeroed in on western or central Nova Scotia as the next target for Noel, which will be a powerful extratropical storm with sustained winds of 60-80 mph on Saturday. The GFDL and and HWRF intensity models show sustained winds of 75 mph impacting Cape Cod and Nantucket Island Saturday afternoon. Tropical storm force winds would affect the coast along eastern Long Island, Rhode Island, the rest of Massachusetts, New Hampshire, and Maine. The GFS and UKMET models take Noel farther east, and bring lower winds in the 4-50 mph range to Cape Cod and Nantucket Island. The GFS and UKMET models are better designed to forecast extratropical systems, so more weight should be given to these models. Still, residents of the Massachusetts coast should be aware of the possibility of damaging winds on Saturday.


Figure 1. Satellite estimated rainfall totals for October 26-31, as estimated by the NASA TRMM satellite.

Noel's death toll
Noel's death toll now stands at 107, with many hard-hit rural areas yet to be heard from. At least 40 people died in Haiti, and in the Dominican Republic, the death toll stands at 66, with 27 missing. According to Reuters, the worst incident appeared to have occurred in the village of Villa Altagracia, outside the Dominican capital Santo Domingo, where two rivers broke their banks and destroyed most of the community of 200 or so houses. Survivors said up to 35 bodies were seen strewn on the river banks there. As many as 52 communities remain isolated due to collapsed bridges and washed out roads, and power is off to over 3 million of the nation's 9.4 million people. The Dominican meteorological service reports that 21.65" (550 mm) of rain fell at Padre Las Casas as of 8am EDT Wednesday. Thankfully, no rain has fallen on the Dominican Republic since dawn today, and Noel's rains may be over. The extreme southwestern tip of Haiti is the only portion of that country to receive more rain from Noel today, and those rains were only about an inch. Noel is the deadliest tropical cyclone to affect the Dominican Republic since Hurricane Georges hit Hispaniola in 1998, killing 380 Dominicans and causing over $1 billion in damage to the county. The death toll for Noel makes it the second deadliest storm this hurricane season, behind Hurricane Felix, which killed 133 people in Nicaragua and Honduras.

Links to follow for Noel
Satellite loop
Long range radar out of Miami, FL
Nassau, Bahamas current weather
Google Maps interface, zoomed in on Nassau, Bahamas

I'll have an update Friday morning.

Jeff Masters

Hurricane

Updated: 7:10 PM GMT en Enero 05, 2012

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Noel's death toll rises to 81; storm heads north through the Bahamas

By: JeffMasters, 1:49 PM GMT en Noviembre 01, 2007

Tropical Storm Noel is finally on its way north, after a long stay by the coast of Cuba. The latest center report from the Hurricane Hunters at 9:18am EDT indicated Noel was not strengthening--the pressure remained at 995 mb, and no winds above 60 mph were measured. Satellite loops show an impressive burst of thunderstorms developing on Noel's east side. The latest Hurricane Hunter report showed that Noel's center jumped about 30 miles eastward to relocate itself under these thunderstorms. This jump lessens the chance that southeast Florida coast will experience sustained winds exceeding 30 mph.

The latest GFDL, SHIPS, and HWRF intensity model runs show little change in Noel's strength, and keep the storm's top winds near 60 mph today. Wind shear is about 20 knots over the storm, and is expected to increase above 30 knots tonight, so it is unlikely Noel will intensify into a hurricane. On Friday, the models agree that Noel will transition to a powerful extratropical storm. Noel is expected to bring winds of 55-65 mph to Nova Scotia and Newfoundland on Saturday. Noel's remains may pass close enough to Nantucket and Cape Cod, Massachusetts to bring sustained winds of 40-50 mph there, according to the latest runs of the HWRF and GFDL models. The GFS model takes Noel farther from Cape Cod, and does not bring tropical storm force winds to Massachusetts.

Noel remains a prodigious rain-maker, and produced over 16 inches of rain in 24 hours over ocean areas near the central Bahamas yesterday (Figure 1). Rainfall totals in the Bahamas should range between 10-15 inches by the time Noel departs. Cuba has fared better, receiving no more than 6 inches of rain. However, the soils were already saturated on the island from previous rains, and flooding has forced many people from their homes, damaging at least 1,000 buildings. Heavy rains on Jamaica created a landslide that killed one person yesterday.


Figure 1. Satellite estimated rainfall totals for the 24 hours ending at 2am EDT Thursday November 1. About 16 inches (400 mm, white colors) fell over ocean areas just south of the central Bahamas. Rainfall rates as high as 1.2"/hour were observed this morning. Image credit: Navy Research Lab, Monterey.

Noel's death toll
Another 1-3 inches of rain fell in the past 24 hours over hard-hit Hispaniola, where the death toll is 80. At least 24 people died in Haiti, where deforestation has led to severe flooding problems. In the Dominican Republic, the death toll stands at 56, with many more missing. At least 6,000 buildings were damaged, and 10 bridges washed out. As many as 39 communities remain isolated due to collapsed bridges and washed out roads, and the power is off to over 3 million of the nation's 9.4 million people. The Dominican meteorological service reports that 21.65" (550 mm) of rain fell at Padre Las Casas in the mountains of the central Dominican Republic as of 8am EDT Wednesday. Another 1-2 inches of rain may fall over the island before Noel's rains finally cease. Noel is the deadliest tropical cyclone to affect the Dominican Republic since Hurricane Georges hit Hispaniola in 1998, killing 380 Dominicans and causing over $1 billion in damage to the county. The death toll for Noel makes it the second deadliest storm this hurricane season, behind Hurricane Felix, which killed 133 people in Nicaragua and Honduras.

Links to follow for Noel
Satellite loop
Camaguey, Cuba radar.
Long range radar out of Miami, FL
Nassau, Bahamas current weather
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Impact on Florida
There is no change to the forecast for Florida. Noel will pass well east of the state, bringing winds of 20-30 mph with gusts to 40 mph along the coast of Florida today. Florida will be on the dry side of Noel, thanks to upper level winds from the west that will be creating about 20-25 knots of wind shear over the storm. Expect occasional heavy rain showers with rain amounts totaling 1-3 inches if you live along the Southeast Florida coast. The main hazard from Noel will be beach erosion, thanks to the 10-foot seas expected to pound area beaches. Wind and seas will subside Friday morning as Noel pulls rapidly away from Florida.

I'll have an update this afternoon.

Jeff Masters

Updated: 2:06 PM GMT en Noviembre 01, 2007

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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.

Local Weather

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