CSU predicts highly active hurricane season; Cyclone Phet approaching Oman
A very active Atlantic hurricane season is on tap for 2010, according to the seasonal hurricane forecast issued June 2 by Dr. Phil Klotzbach and Dr. Bill Gray of Colorado State University (CSU). The CSU team is calling for 18 named storms, 10 hurricanes, and 5 intense hurricanes, and an Accumulated Cyclone Energy (ACE) 185% of average. Between 1950 - 2000, the average season had 10 named storms, 6 hurricanes, and 2 intense hurricanes. But since 1995, the beginning of an active hurricane period in the Atlantic, we've averaged 14 named storms, 8 hurricanes, and 4 intense hurricanes per year. The new forecast is a step up from their April forecast, which called for 15 named storms, 8 hurricanes, and 4 intense hurricanes. The new forecast calls for a much above-average chance of a major hurricane hitting the U.S., both along the East Coast (51% chance, 31% chance is average) and the Gulf Coast (50% chance, 30% chance is average). The risk of a major hurricane in the Caribbean is also high, at 65% (42% is average.) This is the most aggressive early June forecast ever issued by the CSU group; the previous most aggressive such forecasts were for the 2006 and 2007 seasons, when the CSU team predicted 17 named storms, 9 hurricanes, and 5 intense hurricanes. Both of these forecasts did poorly, particularly the 2006 forecast, as only 10 named storms, 5 hurricanes, and 2 intense hurricanes were observed.
The forecasters cited four main reasons for an active season:
1) Weak La Niña conditions should develop by the most active portion of this year's hurricane season (August-October). The expected trend towards weak La Niña conditions should lead to reduced levels of vertical wind shear compared with what was witnessed in 2009.
2) Current SST anomalies are running at near-record warm levels. These very warm waters are associated with dynamic and thermodynamic factors that are very conducive for an active Atlantic hurricane season.
3) A weaker-than-normal Azores High prevailed during April-May. Weaker high pressure typically results in weaker trade winds that are commonly associated with more active hurricane seasons.
4) We are in the midst of a multi-decadal era of major hurricane activity, which began in 1995. Major hurricanes cause 80-85 percent of normalized hurricane damage.
Analogue years
The CSU team picked four previous years when atmospheric and oceanic conditions were similar to what we are seeing this year: weak El Niño to neutral conditions, well above-average tropical Atlantic SSTs, and above-average far North Atlantic SSTs during April - May. Those four years were 2005, the worst hurricane season of all time; 1969, the 3rd worst hurricane season of all time, featuring Category 5 Hurricane Camille which hit Mississippi; 1966, a relatively average year that featured Category 4 Inez that killed 1,000 people in Haiti; and 1958, a severe season with 5 major hurricanes. The mean activity for these five years was 17 named storms, 10 hurricanes, and 5 intense hurricanes, almost the same as the 2009 CSU forecast.
How accurate are the June forecasts?
The June forecasts by the CSU team over the past 12 years have had a skill 19% - 30% higher than a "no-skill" climatology forecast for number of named storms, number of hurricanes, and the ACE index (Figure 1). This is a decent amount of skill for a seasonal forecast, and these June forecasts can be useful to businesses such as the insurance industry and oil and gas industry that need to make bets on how active the coming hurricane season will be. Unfortunately, the CSU June 1 forecasts do poorly at forecasting the number of major hurricanes (only 3% skill), and major hurricanes are what do 80 - 85% of all hurricane damage (normalized to current population and wealth levels.) This year's June forecast uses the same formula as the past two years, which did quite well predicting the 2008 hurricane season (prediction: 15 named storms, 8 hurricanes, 4 intense hurricanes; observed: 16 named storms, 8 hurricanes, 5 intense hurricanes) and 2009 hurricane season (prediction: 11 named storms, 5 hurricanes, 2 intense hurricanes; observed: 9 named storms, 3 hurricanes, 2 intense hurricanes.) An Excel spreadsheet of their forecast skill (expressed as a mathematical correlation coefficient) show values from 0.44 to 0.58 for their June forecasts, which is respectable.
Figure 1. Comparison of the percent improvement over climatology for May and August seasonal hurricane forecasts for the Atlantic from NOAA, CSU and TSR from 1999-2009 (May) and 1998-2009 (August), using the Mean Squared Error. The British firm Tropical Storm Risk (TSR) will issue their outlook for the 2010 Atlantic hurricane season on June 4. Image credit: Verification of 12 years of NOAA seasonal hurricane forecasts, National Hurricane Center.
NOAA's 2010 hurricane season forecast
NOAA issued their forecast for the upcoming Atlantic hurricane season last week. As I discussed in my post on their forecast, NOAA is calling for very active and possibly hyperactive season. They give an 85% chance of an above-normal season, a 10% chance of a near-normal season, and just a 5% chance of a below-normal season. NOAA predicts a 70% chance that there will be 14 - 23 named storms, 8 - 14 hurricanes, and 3 - 7 major hurricanes, with an Accumulated Cyclone Energy (ACE) in the 155% - 270% of normal range. If we take the midpoint of these numbers, NOAA is calling for 18.5 named storms, 11 hurricanes, 5 major hurricanes, and an ACE index 210% of normal. A season with an ACE index over 175% is considered "hyperactive."
Figure 2. Visible satellite image of Tropical Cyclone Phet on Thursday, June 3, 2010.
Tropical Cyclone Phet the 2nd strongest Arabian Sea storm on record
Record heat over southern Asia in May has helped heat up the Arabian Sea to 2°C above normal, and the exceptionally warm SSTs helped fuel Tropical Cyclone Phet into the second strongest tropical cyclone ever recorded in the Arabian Sea. Phet peaked at Category 4 strength with 145 mph winds yesterday, and has weakened slightly to 135 mph winds this morning. Only Category 5 Cyclone Gonu of 2007, which devastated Oman, was a stronger Arabian Sea cyclone.
Phet is over very warm waters of 30 - 31°C, and is under moderate wind shear of 10 - 20 knots. However, the storm is wrapping in dry air from the Arabian Peninsula, which has caused weakening. Visible satellite imagery from this morning (Figure 2) shows that the heavy thunderstorms on the north side of Phet have been eroded away by dry air. Phet is a small storm, and could fall apart fairly quickly if dry air can penetrate into its core. This should happen later today, since wind shear is on the increase, and the shearing winds should be able to disrupt the circulation enough that dry air can force its way into Phet's eyewall. Phet is fairly small, will miss the most heavily populated areas of Oman, and will likely undergo significant weakening before landfall, so the storm is unlikely to cause the kind of catastrophic flooding that Category 5 Cyclone Gonu of 2007 brought to Oman. Gonu killed 50 people and did $4.2 billion in damage. Phet's heaviest rains will be confined to a relatively sparsely populated region of Oman's coast. Rainfall amounts in excess of 6 inches in 18 hours (Figure 3) can be expected along Oman's coast today, which will likely cause extreme flooding.
After Phet's encounter with Oman, the storm will probably be at tropical storm strength when it makes its second landfall in Pakistan. Heavy rains from Phet will be the major danger for Pakistan, and serious flooding can be expected over southern Pakistan.
Figure 3. Forecast rain amounts for the 18-hour period ending at 2am EDT June 3, 2010. Image credit: NOAA/NESDIS.
Oil spill update
Onshore winds out of the south, southwest, or west are expected to blow over the northern Gulf of Mexico over most of the next week, resulting increased threats of oil to Alabama, Mississippi, and the Florida Panhandle, according to the latest trajectory forecasts from the State of Louisiana. The latest ocean current forecasts from the NOAA HYCOM model show that these winds will generate a 0.5 - 1 mph current flowing from west to east along the Florida Panhandle coast Sunday and Monday. If this current develops as predicted, it will be capable of bringing light amounts of oil as far east as Fort Walton Beach, Florida, by Monday. If you spot oil, send in your report to http://www.gulfcoastspill.com/, whose mission is to help the Gulf Coast recovery by creating a daily record of the oil spill.
Oil spill resources
My post, What a hurricane would do the Deepwater Horizon oil spill
My post Wednesday with answers to some of the common questions I get about the spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami
I'll be back Friday with an analysis of the new TSR hurricane forecast and a new forecast by a promising Florida State University model.
Jeff Masters
Reader Comments
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The current cap for the BOP is different than previous fixtures ("top hat" etc) as it has lines to pump the equivalent of a "de-icer" into the capture area of the cap. The hydrate buid up Patrap discussed is indeed a possible reason for the current blow-by we are seeing. That said, the cap has been under suction since they began lowering it today. It is key to lowering it into place and guiding it as without that suction the cap would bounce side to side and be hard to control. There does seem to be a problem of flow rate which could be due to hydrate "icing" in the tube farther up the suction pipe. The "de-icing" capability has difficulty handing hydrate ice build-up if it occurs too far away from their nozzle in the cap.
Ok I was just wondering if there was a reason I wasn't aware of so I didn't do it. Thanks
Brilliant.
BP = BIG PR*CKS!!!
sorry... rage chokes sometimes.
We can always change the channel
The oil spill is on topic, Dr. Masters mentioned it in his post.
That was to btwntx08
Because this needs to be said twice. He might miss it on page 36. No way I'm letting that happen.
The blob north of the Virgins should be labelled an invest.
BROAD UPPER LEVEL ANTI-CYCLONIC FLOW COVERS THE FAR EASTERN AND WESTERN ATLANTIC AREA OF DISCUSSION THIS EVENING. HOWEVER...AN UPPER LEVEL LONGWAVE IS OVER THE CENTRAL ATLANTIC, RIGHT IN BETWEEN THESE TWO AREAS OF ANTI-CYCLONIC FLOW, SUPPORTING AN AREA OF WEAK SURFACE TROUGHINESS FROM 20N TO 30N BETWEEN 34W AND 48W. WEAK TO ISOLATED MODERATE CONVECTION IS WITHIN THIS REGION.
COMPUTER MODELS SHOW THIS AREA OF CONVECTION WILL DIMINISH OVER THE NEXT 24 TO 36 HOURS. A SURFACE TROUGH IS ANALYZED OVER THE WESTERN ATLANTIC ALONG 25N68W 23N72W 20N74W. MODERATE TO ISOLATED MODERATE CONVECTION IS FOUND EAST OF THE SURFACE TROUGH...FROM 21N TO 26N BETWEEN 65W AND 71W. WEAK UPPER LEVEL DIVERGENCE EAST OF THE BAHAMAS IS FURTHER SUPPORTING THE CONVECTION IN THIS REGION. THIS SURFACE TROUGH IS EXPECTED TO SLOWLY MOVE EASTWARD AS THE CONVECTION WEAKENS OVER THE NEXT 24 HOURS. NO SIGNIFICANT WEATHER IS OCCURRING OR EXPECTED TO DEVELOP ELSEWHERE ACROSS THE ATLANTIC.
Excellent point. But hr regularly references politics and GW and we can still be banned for that.
They can screw him just like he screwed our gulf!
We all get headaches from time to time. It's all a part of too much information:
So wrong ... this isnt opinion .. this isnt debatable. This is a disaster of epic proportions and demands the attention of any media outlets, not excluding a "weather" blog. I do not think the Doc would have any problems with the majority of what is being said (though I dont know if he approves of us setting Mr "I want my life back" adrift in the oil slick .... but oh well)
1)their share holders would have to approve their chapter 11 request and that isn't likely
2)A court would have to approve a chapter 11 hearing and they wont touch it
3)they are still making money hand over fist
Looks like it's not going to encounter any shear higher than 20-25 kt.
Hi Astro...it's called a surface trough right now..."THIS SURFACE TROUGH IS EXPECTED TO SLOWLY MOVE EASTWARD AS THE CONVECTION WEAKENS OVER THE NEXT 24 HOURS."
I absolutely agree with you. The weather blog is not a media outlet.
Thanks for the reponse. And that's good news, as least they will always be on the hook.
Well I can understand his refrences to them when he is talking about weather, but sometimes the discussions on here spiral out of control and have absolutley nothing to do with meteorology or geosciences.
BP is a British based company, so it gets really complicated.
The nation of Oman I believe is almost entirely a very dry desert. The 6 inches of rain in 18 hrs will produce catastrophic flash flooding!!
From www.iexplorer.com:
Oman's climate is mainly hot and dry, particularly in the scorching barren interior where summer temperatures can soar to 130F (54C). On the coast humidity can be high during the summer months. Milder temperatures and a more temperate climate are found in the southern Dhofar region, which experiences heavy monsoon rains between June and September each year. In general the rest of the country experiences low and irregular rainfall.
It's called "Hurricane Season Tourette Syndrome". farely common.
It'll pass Nov. 30th..... could be later???
I wont say what I want to because Im sure Im angry about the oil spill and that would cause my tongue to lash harder than it should. I will say this though. ignored.
Ah its a medicinal mud bath, the birds will be fine....from BP !
eh your loss. I was agreeing with you.
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