CSU and TSR predict an extremely active 2011 Atlantic hurricane season

By: Dr. Jeff Masters , 12:54 PM GMT on December 09, 2010

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A continuation of the pattern of much above-average Atlantic hurricane activity we've seen since 1995 is on tap for 2011, according to the latest seasonal forecast issued Wednesday by Dr. Phil Klotzbach and Dr. Bill Gray of Colorado State University (CSU). They are calling for 17 named storms, 9 hurricanes, and 5 intense hurricanes. An average season has 10 - 11 named storms, 6 hurricanes, and 2 intense hurricanes. The new forecast is a very aggressive one, since only six seasons since 1851 have had as many as 17 named storms; 19 seasons have had 9 or more hurricanes. The 2011 forecast calls for a much above-average chance of a major hurricane hitting the U.S., both along the East Coast (49% chance, 31% chance is average) and the Gulf Coast (48% chance, 30% chance is average). The Caribbean is forecast to have a 62% chance of seeing at least one major hurricane (42% is average.) Five years with similar pre-season November atmospheric and oceanic conditions were selected as "analogue" years that the 2011 hurricane season may resemble: 2008, 1999, 1989, 1961, and 1956. The average activity for these years was 12 named storms, 7 hurricanes, and 4 major hurricanes.

The forecasters cited several reasons for their forecast of a much above-average season:

1) Unusually warm sea surface temperatures continue in the tropical Atlantic this fall, an indication that the active hurricane period we have been in since 1995 will continue (in technical terms, the positive phase of the Atlantic Multidecadal Oscillation, AMO, will continue.) SSTs in Atlantic Main Development Region (MDR) for hurricanes, from the Caribbean eastwards to the coast of Africa, were at a record high in October (November data are not yet available.)

2) Hurricane activity in the Atlantic is lowest during El Niño years and highest during La Niña or neutral years. This occurs because El Niño events tend to increase westerly upper-level winds over the tropical Atlantic, bringing high wind shear harmful for hurricanes. The CSU team notes that we are currently experiencing moderate to strong La Niña conditions, with an unusual amount of cool water present in the top 300 meters of the Equatorial Pacific Ocean off the coast of South America. Since 1979, only eight years have had similar amounts of cool water in November. The hurricane seasons that followed each of those eight years were unable to transition to El Niño conditions. Thus, the CSU team expects that we will have neutral or La Niña conditions in place for the Atlantic hurricane season of 2011, which should act to keep wind shear values average to below average, enhancing hurricane activity. Of the 16 El Niño/La Niña computer models that made November predictions for the July-August-September 2011 portion of hurricane season (Figure 1), only 4 (25%) predicted that El Niño would arrive.

How accurate are the December forecasts?
The CSU real-time December forecasts did not shown any skill over the period 1992 - 2007, so the forecast scheme was overhauled and a new scheme implemented for the forecasts made for the 2008 - 2010 hurricane seasons. This new scheme showed some decent skill in those three years, with skill levels 18%, 10%, and 30% above chance for predicting the number of named storms, hurricanes, and intense hurricanes, respectively. Still, three years is too short of a time period to evaluate the skill of these December forecasts, and we should view the latest forecast as an experimental research product. Last year's December forecast for the 2010 hurricane season predicted 13.5 named storms, 7 hurricanes, and 4 intense hurricanes. The actual numbers were 19 named storms, 12 hurricanes, and 5 intense hurricanes.


Figure 1. Forecasts of El Niño conditions by 20 computer models, made in November 2010. The longest range forecasts for July-August-September (JAS) at the right side of the image show that 4 models predict weak El Niño conditions, 7 predict neutral conditions, and 5 predict a weak to moderate La Niña. El Niño conditions are defined as occurring when sea surface temperatures in the Equatorial Pacific off the coast of South America (the "Niño 3.4 region) rise to 0.5°C above average (top red line). La Niña conditions occur when SSTs in this region fall to 0.5°C below average. Image credit: Columbia University.

2011 Atlantic hurricane season forecast from Tropical Storm Risk, Inc.
The British private forecasting firm Tropical Storm Risk, Inc. (TSR), issued their 2011 Atlantic hurricane season forecast on Monday. They are also calling for a very active year: 15.6 named storms, 8.4 hurricanes, and 4 intense hurricanes. TSR predicts a 66% chance of an above-average hurricane season, 22% chance of a near-normal season, and only a 12% chance of a below normal season. TSR bases their December forecast on predictions that sea surface temperatures next fall in the tropical Atlantic will be above about 0.3°C above average, and trade wind speeds will be about 0.7 m/s slower than average. The trade wind speed prediction is based on a forecast for a weak La Niña in August-September 2011.

I like how TSR puts their skill level right next to the forecast numbers: 2% skill above chance at forecasting the number of named storms, 1% skill for hurricanes, and 7% skill for intense hurricanes. That's not much skill, and really, we have to wait until the June 1 forecasts by CSU, NOAA, and TSR to get a forecast with reasonable skill.

Comparing 2005 and 2010 steering currents
The U.S. got extremely fortunate during the 2010 hurricane season that the steering currents carried most of the storms out to sea, or forced them to the south. A very graphic way of looking at this is to compare the amount of rain that fell due to tropical cyclones in the Atlantic in 2005 versus 2010 (Figure 2.) The U.S. received a direct hit only from Tropical Storm Bonnie, which hit South Florida as a minimal 40 mph tropical storm and caused no significant damage. TSR is predicting that this luck will not hold in 2010; they project that five named storms will hit the U.S., with two of these being hurricanes.


Figure 2. Rainfall amounts due to all Atlantic tropical cyclones in 2005 and 2010, as measured by NASA's TRMM satellite. Steering currents in 2010 tended to recurve many storms out to sea between the Caribbean and Bermuda, due to a large number of unusually strong troughs of low pressure moving off the U.S. East Coast.

Weekend winter storm for Eastern U.S.
The latest 06Z (1am EST) set of computer model forecasts for this weekend's winter storm over the Midwest and Eastern U.S. point towards a more northerly path for the storm, bringing the axis of heaviest snow through Wisconsin and Michigan. There is still a great deal of uncertainty in the predicted timing and strength of the storm, but a renewed blast of cold air Monday and Tuesday over the Southeast U.S. is still highly likely in the wake of the storm.

Jeff Masters

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331. Jax82
7:17 PM GMT on December 10, 2010
Member Since: September 2, 2008 Posts: 1 Comments: 1261
329. eddye
7:03 PM GMT on December 10, 2010
jeff wat the latest models showing colder air for this monday
Member Since: August 12, 2008 Posts: 0 Comments: 1204
325. Neapolitan
6:47 PM GMT on December 10, 2010
Climate change: still think it’s a myth?

"As the snow gently falls across northern Europe, many of those who’d rather believe we don’t have a [global warming] problem take comfort from the wintry weather. But many of the people who take snow and ice as affirmation for a policy of doing nothing have become confused between trends and events. For a while the snow gives the impression that temperatures are getting cooler but the global average readings tell a different story. Throughout 2010, high temperature records have been broken in country after country and this year will be one of the warmest on record. Sure, it’s cold outside, but the natural variability we experience every day in the changing weather must not be confused with the trends that are embedded in longer-term climatic patterns. The trend data show that the world is warming, that the climate is changing and that the release of greenhouse gases is the cause...Each day more and more of these heat-trapping gases accumulate in the atmosphere. Tick tock, tick tock."

More...
Member Since: November 8, 2009 Posts: 4 Comments: 13306
323. Patrap
6:46 PM GMT on December 10, 2010
Santa endorses the wunderground and use's the site for Navigating Xmas Eve.

He has a Blog here as well,,but he is Banned ATM.

Something about Yukon Cornelius and a NOLA Blogger getting into it.
Member Since: July 3, 2005 Posts: 415 Comments: 125722
322. tornadodude
6:42 PM GMT on December 10, 2010
Quoting Patrap:
Fla, hasnt had a Hurricane Strike since Oct 05.

The Shields hold fast as the Shower curtain Defense remains intact.


I was obviously being a little sarcastic :pp

and yeah, surprisingly no shower curtain blog appearances on awhile
Member Since: June 28, 2006 Posts: 24 Comments: 8185
321. Patrap
6:37 PM GMT on December 10, 2010
Fla, hasnt had a Hurricane Strike since Oct 05.

The Shields hold fast as the Shower curtain Defense remains intact.
Member Since: July 3, 2005 Posts: 415 Comments: 125722
320. Patrap
6:36 PM GMT on December 10, 2010





SSEC Global Composite Images


The Composite World image is a small image produced every three hours that shows the entire world. It is not useful for seeing specific systems, but it is useful to get an overview of what storms are going on in the world.
Member Since: July 3, 2005 Posts: 415 Comments: 125722
319. tornadodude
6:36 PM GMT on December 10, 2010
Quoting caneswatch:


Haha, sike.


oh come on, everyone knows that Florida is the most likely target for a major hurricane :p
Member Since: June 28, 2006 Posts: 24 Comments: 8185
318. Patrap
6:35 PM GMT on December 10, 2010
D-o-o-m-e-d?
Member Since: July 3, 2005 Posts: 415 Comments: 125722
317. TampaFLUSA
6:35 PM GMT on December 10, 2010
Are the models trending colder again?
Member Since: June 21, 2007 Posts: 10 Comments: 1657
315. caneswatch
6:26 PM GMT on December 10, 2010
Quoting Jeff9641:


Thanks for the heads up RufusBaker.


Haha, sike.
Member Since: October 8, 2008 Posts: 14 Comments: 4553
314. yonzabam
6:19 PM GMT on December 10, 2010
Mortality is over 50% if they don't get medical attention. So, I'm surprised it's as low as 3%.
Member Since: July 20, 2008 Posts: 0 Comments: 2450
313. yonzabam
6:17 PM GMT on December 10, 2010
So, now the Caribbean islanders and people living in central America are going to have to put up with virulent cholers epidemics as well as an increased frequency of hurricanes and intense rain events?

At least we can't blame global warming for the introduction of the new strain into the region. But, higher temperatures and more rain could make outbreaks worse.

Member Since: July 20, 2008 Posts: 0 Comments: 2450
312. aspectre
6:10 PM GMT on December 10, 2010
Was wondering about that. Had read that cholera normally has 1% mortality rate amongst those who receive medical attention (mostly rehydration therapy), yet the figures coming out of Haiti indicated a death rate of 3%.
Member Since: August 21, 2007 Posts: 0 Comments: 4860
310. hydrus
5:52 PM GMT on December 10, 2010
Quoting Ossqss:
Ok, now this is getting ridiculous. While the UN global warming/redistribution of wealth conference is in full swing in Cancun, they have now experienced 6 days of record low temperatures in a row and it looks like several more to come and perhaps a record cold month. That is well past ironic coincidence ..... see for yourself. The atmosphere must be gearing up for the visit from Orca :)

http://www.wunderground.com/history/airport/MMUN/2010/12/10/DailyHistory.html

Have not seen that commercial in a while . :)
Member Since: September 27, 2007 Posts: 1 Comments: 19608
309. Ossqss
5:33 PM GMT on December 10, 2010
Ok, now this is getting ridiculous. While the UN global warming/redistribution of wealth conference is in full swing in Cancun, they have now experienced 6 days of record low temperatures in a row and it looks like several more to come and perhaps a record cold month. That is well past ironic coincidence ..... see for yourself. The atmosphere must be gearing up for the visit from Orca :)

http://www.wunderground.com/history/airport/MMUN/2010/12/10/DailyHistory.html

Member Since: June 12, 2005 Posts: 6 Comments: 8183
308. tornadodude
5:07 PM GMT on December 10, 2010
Quoting Some1Has2BtheRookie:


Yes. Now we all have clearer image of what they mean by "service". LOL


what about community service? :P
Member Since: June 28, 2006 Posts: 24 Comments: 8185
307. SQUAWK
4:51 PM GMT on December 10, 2010
AMY!!!!!
Member Since: December 9, 2008 Posts: 0 Comments: 2498
306. Some1Has2BtheRookie
4:46 PM GMT on December 10, 2010
Quoting Orcasystems:
while I wait for the rain to stop...

Service

I became confused when I heard the word " Service " used with these agencies:

Revenue ' Service '
Postal ' Service '
Telephone ' Service '
Cable TV ' Service '
Civil ' Service '
Customer ' Service '

This is not what I thought ' Service ' meant.

Today, I heard two farmers talking, one of them said he had leased a bull to ' Service ' all his cows.

BAM!!! It all came into focus.


Yes. Now we all have clearer image of what they mean by "service". LOL
Member Since: August 24, 2010 Posts: 0 Comments: 4732
305. NRAamy
4:42 PM GMT on December 10, 2010
SQUAWK!!!!!!!

:)
Member Since: January 24, 2007 Posts: 316 Comments: 31944
304. RipplinH2O
4:29 PM GMT on December 10, 2010
Go to Sunday morning in Navarre, FL and see if the rain is light enough to golf in...
Member Since: July 30, 2010 Posts: 0 Comments: 491
302. RufusBaker
4:17 PM GMT on December 10, 2010
Just got back from the summer of 2011 in my time machine. 7 major canes hit U.S. 2 hit Tampa directly
Member Since: July 5, 2009 Posts: 0 Comments: 578
301. SuperYooper
4:09 PM GMT on December 10, 2010
Quoting aislinnpaps:
Good morning, everyone. Sorry for my disappearance, I had a house fire and lost my house. We're all fine, one son and I had smoke inhalation from rescuing pets. It's been rough though, I still lost some dogs, all but one cat and my three parrots. Pray that the weather stays clear for the next week and a half so they can get a small doublewide onto my property so my kids don't spend Christmas in a motel room.


I had a grandmother pass two weeks before my wedding. What doesn't take you out only makes you stronger expecially when it happens around events. It's tough now but you'll pull through even stronger than what you were before! Best wishes!
Member Since: August 18, 2010 Posts: 14 Comments: 1601
I think we in the Marquette area are going to be the big winners (if you want to call us that) for the stormy weekend. Predicting 24"+ for our area. Make sure you make your reservations at Marquette Mountain Ski now! :)
Member Since: August 18, 2010 Posts: 14 Comments: 1601
Quoting atmoaggie:
Loving this weather. (In SE LA).


Quoting atmoaggie:
Possible that station's temps calibrated a little low...



Already showing lower that our forecast low. (31 F)

On second look, Slidell recorded a 31 (30 minutes ago) when the forecast low there was 32 (~20 miles east of me). Maybe it's right!


Hey Atmo! Did you ever get over to Baby's Coffee?
Member Since: Posts: Comments:
Quoting PensacolaDoug:
Re: 279


One of those "it's all clear to me now moments!"


Hey Orca! Why am I Indefinitely banned from your blog? I'm house-broken!


I wasn't even aware you were... let me check.

Your not now.. must have been during the Blog wars... I put a lot of people on during that, I found it made life so much quieter.
Member Since: Posts: Comments:
Quoting aislinnpaps:
Good morning, everyone. Sorry for my disappearance, I had a house fire and lost my house. We're all fine, one son and I had smoke inhalation from rescuing pets. It's been rough though, I still lost some dogs, all but one cat and my three parrots. Pray that the weather stays clear for the next week and a half so they can get a small doublewide onto my property so my kids don't spend Christmas in a motel room.


That is absolutely horrible. I am so sorry for your loss. At least your family is safe and some of your pets made it. Good luck to you in the recovery. I hope everything works out for the holidays. It's never a good time for such an event but around the holidays is bad timing for sure. Stay safe...
Member Since: Posts: Comments:
Oops. NWS missed by a little last night. I really was below my forecast low by 9 pm.

For Slidell (official ob site), the forecast was 32 F.

25 F recorded: http://www.weather.gov/data/obhistory/KASD.html

Hope no one lost pets/plants/people(!?!) expecting 32 and getting 25...was below 32 for 12 hours!
Member Since: Posts: Comments:
Link


Cue the theme from "JAWS".
Member Since: Posts: Comments:
Re: 279


One of those "it's all clear to me now moments!"


Hey Orca! Why am I Indefinitely banned from your blog? I'm house-broken!
Member Since: Posts: Comments:
For West Palm Beach

Member Since: Posts: Comments:
290. eddye
jeff look at accuweather it shows 40
Member Since: August 12, 2008 Posts: 0 Comments: 1204
Quoting Orcasystems:
Complete Update

It would appear.. that in the next few days.. the weather Gods are going to get even with KOG






getting even naw just a nice snow base and cold air to work with after iam done with the south you are next
Member Since: Posts: Comments:
Well the NAO is dropping now, as the storm moves eastward, a low should develop along the coast and enhance the GLC. Unfortunatly the EURO had the right idea all along and nailed this storm. I really had some hopes of it being wrong but on the good side of things, if u like snow, the East Coast (big cities) will indeed see some snow out of this as the cold front sweeps through the moisture. So we should have a rain/snow band moving eastward. Accumulations of an inch or two is possible in the areas the snow band hits the hardests.
Member Since: Posts: Comments:
285. eddye
jeff it shoiws orlando at 39 degrees on the 18th
Member Since: August 12, 2008 Posts: 0 Comments: 1204
Quoting eddye:
jeff 9641 how cold does it show south florida geting


This coming Monday we may get a freeze which is totally crazy for December.



Good morning and happy Friday to you all!


Was watching the local weather last night for Ft Lauderdale area.
While we knew we broke over 150 year old "low temp" records last week and last weekend...

last night we found out that every day this week we broke the
record for the "lowest high temp" on these dates.
records set over 100 years ago!

Hope to actually reach 70's today and tomorrow then another bad artic blast..
the next freeze in the interior farm lands will finish off all the veggies that barely survived last week's frost/freeze...

Merry Christmas!

Gams



Glitterfy.com - christmas Glitter Graphics
Member Since: Posts: Comments:
281. eddye
jeff 9641 how cold does it show south florida geting
Member Since: August 12, 2008 Posts: 0 Comments: 1204

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