Early 2011 Atlantic Hurricane Season Forecasts

By: Dr. Jeff Masters , 6:22 AM GMT on April 07, 2011

Share this Blog
6
+

Hi everybody, this is Dr. Rob Carver filling in for Dr. Masters. 

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 April 6 by Dr. Phil Klotzbach and Dr. Bill Gray of Colorado State University (CSU). They are calling for 16 named storms, 9 hurricanes, and 5 intense hurricanes. An average season has 10 named storms, 6 hurricanes, and 2 intense hurricanes. The new forecast is nearly identical to their forecast made in December, which called for 17 named storms, 9 hurricanes, and 5 intense hurricanes. 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 (48% chance, 31% chance is average) and the Gulf Coast (47% chance, 30% chance is average). The Caribbean is forecast to have a 61% 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, 1996, 1955, and 2006.  The first four years listed all had neutral to La Niña SST's during hurricane season, while 2006 had El Niño SST's.  The average activity for these years was 12.6 named storms, 7.8 hurricanes, and 4.8 major hurricanes.

This year, the forecasters have introduced a new statistical model for their  April forecasts.  There are four components in this model:

1. Average sea-level pressure in March around the Azores in the subtropical Atlantic.

2. The average of January through March sea-surface temperatures (SST's) in the tropical Atlantic off the coast of Africa.

3. Average sea-level pressure in February and March for the southern tropical Pacific ocean west of South America.

4. Forecasts of September's SST in the tropical Pacific using a dynamical model from the European Centre for Medium-Range Weather Forecasts (ECMWF) 

The first two components are loosely linked together.  Statistical studies have shown that a weaker subtropical high near the Azores, combined with warmer SST's off the coast of Africa in March are associated with weak winds near the surface and aloft from August to October.  This decrease in wind speeds reduces wind shear which can disrupt forming storms.  These March conditions also are associated with warmer SST's in August to October, which is also favorable for more tropical storms.   For this forecast, the first component is strongly favorable for increased hurricane activity, while the second component is weakly negative.

The last two components represent the changes in sea-surface temperature and sea-level pressure that are the El Niño-Southern Oscillation (ENSO).  Briefly speaking,  El Niño conditions (warm sea-surface temperatures) are not favorable for Atlantic hurricanes.  For more info on ENSO and hurricanes, Jeff has this article.

Using the ECMWF model as guidance (see Figure 1), the CSU group believes that SST's in the tropical Pacific will be neutral (less than 0.5°C from normal).  This would have a small negative effect on hurricane activity.  However, the tropical Pacific sea-level pressure shows that the atmosphere looks like a La Niña event is still going on.  This is strongly favorable for Atlantic hurricane activity in the CSU group's model.

Figure 1. Forecasts of El Niño conditions by 20 computer models, made in March 2011. The ECMWF forecast used by the CSU group is represented by the dark orange square.  The forecasts for August-September-October (ASO) show that 5 models predict 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.

How accurate are the April forecasts? While the formulas used by CSU do well in making hindcasts--correctly modeling the behavior of past hurricane seasons--their April hurricane season forecasts have had no skill in predicting the future. This year's April forecast is using a new system and has not yet produced a verified forecast.  The scheme used in the past three years successfully predicted active hurricane seasons for 2008 and 2010, but failed to properly predict the relatively quiet 2009 hurricane season. A different formula was used prior to 2008, and the April forecasts using that formula showed no skill over a simple forecast using climatology. CSU maintains an Excel spreadsheet of their forecast errors ( expressed as a mathematical correlation coefficient, where positive means a skilled forecast, and negative means they did worse than climatology) for their their April forecasts. For now, these April forecasts should simply be viewed as an interesting research effort that has the potential to make skillful forecasts. The next CSU forecast, due by June 1, is the one worth paying attention to. Their early June forecasts have shown considerable skill over the years.


Figure 2.
Accuracy of long-range forecasts of Atlantic hurricane season activity performed by Phil Klotzbach and Bill Gray of Colorado State University (colored squares) and Tropical Storm Risk, Inc. (colored lines). The CSU team's April forecast skill is not plotted, but is less than zero. The skill is measured by the Mean Square Skill Score (MSSS), which looks at the error and squares it, then compares the percent improvement the forecast has over a climatological forecast of 10 named storms, 6 hurricanes, and 2 intense hurricanes. TS=Tropical Storms, H= Hurricanes, IH=Intense Hurricanes, ACE=Accumulated Cyclone Energy, NTC=Net Tropical Cyclone Activity. Image credit: TSR.

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 April 5. They are also calling for  a  very  active  year: 14. 2 named storms, 7.5 hurricanes, and 3.6 intense hurricanes. We would round that to 14 named storms, 8 hurricanes, and 4 intense hurricanes.   This  compares to their forecast issued in December of 15.6 named storms, 8.4 hurricanes,   and intense hurricanes. TSR predicts a 55%  chance  of  an  above-average  hurricane season, 28% chance of a near-normal season, and only a 17%  chance  of  a  below normal season. TSR bases their April forecast on predictions  that  sea  surface temperatures this fall in the tropical  Atlantic  will  be  above  about  0.08°C above average, and trade  wind  speeds  will  be  about 0.2  m/s  slower  than average.  The decrease in the trade wind speeds is favorable for enhanced hurricane activity, while the forecast SST's are expected to be neutral for hurricane activity.

TSR puts their skill level right next to the forecast numbers: 13% skill above chance at forecasting the number of named storms, 11% skill for hurricanes, and 10% 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.

Rob's critiques of the April forecasts
I have to note that Jeff and I wrote this article together.  He wrote the general framework before the forecasts were issued, while I wrote the details based on the actual forecasts.  So the preceding text is a joint production.  However, I have a few observations to make that are my responsibility alone.

First, I am disappointed that the CSU group has changed forecast models only after three seasonal forecasts.  This makes it very difficult to assess the skill of the current forecast using past performance.  This is very important for forecast users, and they do it everyday.  For example, I tend to discount a forecast of rain if it comes from a source that over-forecasts rain (The boy who cried wolf problem).

In the documentation that came with the April forecast, the CSU group argue that the hindcasts show the new forecast model has skill.  However, I think hindcasts are a poor substitute for real forecasts in understanding the skill of a statistical forecast model, like that of the CSU's group.  As Jeff noted, the previous forecast model did well with the hindcasts and yet had mixed results with the actual forecasts.  This does not give me confidence that the new forecast model will be superior to the previous model.

From a philosophical viewpoint, I am inherently cautious about statistical forecast models like the one used by the CSU group.  Essentially, they look at what happened in the past and use that to predict the future.  However, for making forecasts, we assume that the relationships in space and time between the predictors (such as the average March sea-level pressure around the Azores) and the predictands (Atlantic hurricane activity) does not change as we move forward in time.  In a world with climate change, that's a tricky assumption to make.

In any event, it is customary in the meteorological community to continue running older forecast guidance models after the introduction of newer models.  This allows forecasters and forecast users to leverage their knowledge of the forecast skill of the older model and gain insight into the forecast skill of the new model.  The CSU group really should have included the forecast from the previous statistical forecast system in this forecast.     

I am uneasy with some of the methodology choices made in implementing the forecast model.  Data for the first three predictors was obtained from the Climate Forecast System Reanalysis (CFSR), NOAA's newest and most advanced reanalysis product.  However, CFSR data for 2010 and 2011 has not been released yet, so the CSU group used NCEP/NCAR Reanalysis (NNR), NOAA's first-generation reanalysis, to fill in the gaps.  Due to differences in design, resolution, etc., CFSR and NNR can have different depictions of the state of the atmosphere.  So using NNR's March 2011 average SLP instead of CFSR's could alter the forecast in unexpected ways.  It would be interesting to see how CFSR's 2010-2011 data changes the results. 

In any event, we will have to wait and see what the Atlantic hurricane season of 2011 brings.

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 734 - 684

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35Blog Index

Quoting Grothar:



I was just about to post this, can't believe you mentioned it.



Guten Abend Grothar.

I was just about to post it then I saw that you and Plaza had already beaten me to it. I watched the video and I could give you a summary of what is said in there.

"State of emergency on the A19 near Rostock. More than 50 vehicles were involved in large scale collisions, among them a road tanker. Several people were killed and many badly injured.

An unusual weather phenomenon presumably caused the multi-vehicle collision. According to eye-witnesses, hurricane force gusts raised dust and a tornado-like sand storm formed. This reduced visibility to less than 1 meter. The bad conditions led to collisions on roadways in both directions. Several vehicles were set ablaze.

A large contingent of emergency services, including several helicopters, arrived at the scene and the state of emergency was declared."

On the German yahoo site I found more detailed information. The article speaks of several collisions killing 8 and severely injuring 27 people and over 80 vehicles were involved. In the worst collision 17 cars and 3 trucks burnt out completely, one of them allegedly carried liquid carbon hydride but this has not yet been confirmed.
Member Since: Posts: Comments:
.
Member Since: July 15, 2006 Posts: 168 Comments: 53285
a dirty slide yankee swisher? rameriz now retired. are his records worthless? oh im sorry thought i was on mlb
Member Since: Posts: Comments:
730. Skyepony (Mod)
Quoting TampaTom:


The National Hurricane Conference - I am moderating two panels:

Crisis Communications: Case studies in Successful public outreach

Reaching out: Social Vulnerability in emergency public information

And, I'll be teaching in:

How social media is being used today by Emergency Management and media in disasters.

Should be fun...


Fugate in 2004 was about the best I've seen.
Member Since: August 10, 2005 Posts: 161 Comments: 37159


Good ole seabreeze looking good today
Member Since: August 7, 2010 Posts: 0 Comments: 1933
National Hurricane Conference FACEBOOK page
Member Since: Posts: Comments:


2011 National Hurricane Conference

April 18-22|Hyatt Regency Atlanta|Atlanta, GA

The nation's forum for education and professional training in hurricane and disaster preparedness!



Purpose of the Conference

The primary goal of the National Hurricane Conference is to improve hurricane preparedness, response, recovery and mitigation in order to save lives and property in the United States and the tropical islands of the Caribbean and Pacific. In addition, the conference serves as a national forum for federal, state and local officials to exchange ideas and recommend new policies to improve Emergency Management.

To accomplish these goals, the annual conference emphasizes:



* Lessons Learned from Hurricane Strikes.

* State of the art programs worthy of emulation.

* New ideas being tested or considered.

* Information about new or ongoing assistance programs.

* The ABC's of hurricane preparedness, response, recovery and mitigation -- in recognition of the fact that there is a continual turnover of emergency management leadership and staff.
Member Since: Posts: Comments:
Quoting TampaTom:


The National Hurricane Conference - I am moderating two panels:

Crisis Communications: Case studies in Successful public outreach

Reaching out: Social Vulnerability in emergency public information

And, I'll be teaching in:

How social media is being used today by Emergency Management and media in disasters.

Should be fun...

Please remind them that all forms of media must be used during a disaster. A lot of people are without electricity and there are still a lot of poor folks who have no computers or iphones and the elderly who do not want or can't afford such devices.
Member Since: Posts: Comments:
Quoting CybrTeddy:


Already had 90L in March.
90L in march yep and the first invest in may will be 91L unless we get 91 in april and hey anything is possible anything

faster and faster we go
Member Since: July 15, 2006 Posts: 168 Comments: 53285
Is it a new particle, or just a fluke?
By Elizabeth Landau, CNN
April 8, 2011 2:36 p.m. EDT


(CNN) -- In the search for answers to some of the most mysterious and fundamental questions about the the universe, Europe's $10 billion particle-smashing Large Hadron Collider has been hogging the spotlight in recent years.

Suddenly, this week, physics enthusiasts' eyes turned to Tevatron, a much smaller and less powerful particle accelerator in Batavia, Illinois, that is scheduled to be shut down for good after September. And, depending on what happens with the budget crisis on Capitol Hill, it could be even sooner.

At Tevatron, part of the Fermi National Accelerator Laboratory (Fermilab), scientists said they may have found evidence of a particle never observed before. That would mean a brand new building-block of matter would be added to what physicists know about the universe.

But the keyword is "may" -- there's a 1 in 1,000 chance that it's just a fluke of statistics. In the coming weeks and months, additional data from Tevatron's detectors and the Large Hadron Collider will probably deliver a more definitive answer about whether indeed a new particle has been discovered.

"If it is true, then it's of course very important. But there's a big if," said Csaba Csaki, associate professor of physics at Cornell University, who was not involved in the experiment.

What they're looking for

Research at particle accelerators often addresses big questions that get at the very nature of existence: Why do we -- and everything around us -- have mass?

One theory that has gained a lot of attention is that there is a particle called the Higgs boson that has this power of giving particles mass. For that reason it has been deemed the "God particle" in popular culture.
Member Since: Posts: Comments:
Quoting TampaTom:




Social Media has definitely changed the way us humans communicate. This is a good way to get information out during times of disasters. Wish it was around when I was in EM 15 years ago
Member Since: August 7, 2010 Posts: 0 Comments: 1933
Quoting gordydunnot:
History channel has storm of the century on at this moment it's about 1935 hurricane in the Keys. Not trying to be coy here but shutter to think if that scenario ever plays out again. Will be cash building only in the Keys because there won't be any insurance.
That might happen anyway if the Governor has his way. The rest of Fl., especially the coastal regions need to be up on what the State Legislature is planning to do to "help" the insurance industry. They are going to stick it to the rest of us.
Member Since: Posts: Comments:
Quoting KEEPEROFTHEGATE:
and its name is mrs. Grothar


Who told????
Member Since: Posts: Comments:
Quoting PlazaRed:
European news reports:-

Over 10 people killed and over 100 injured in severe sand storms in Germany.
The sand storms blocked visibility on motorways and traffic which is not speed restricted on some motorways was involved in pile ups.
Apparently these sandstorms are not uncommon in Germany. Makes you wonder why they don't have speed limits? That may affect fast car sales, of course!!



I was just about to post this, can't believe you mentioned it.

Member Since: Posts: Comments:
716. CybrTeddy


Im well aware of that,,tyvm.
Member Since: Posts: Comments:
Quoting emcf30:
TampaTom, what venue are you going to be teaching at?


The National Hurricane Conference - I am moderating two panels:

Crisis Communications: Case studies in Successful public outreach

Reaching out: Social Vulnerability in emergency public information

And, I'll be teaching in:

How social media is being used today by Emergency Management and media in disasters.

Should be fun...
Member Since: Posts: Comments:
Quoting emcf30:
Wasn't this the same type of weather pattern last year that kept all the 'canes going out to sea?
Member Since: Posts: Comments:
Quoting Patrap:
Am going with May 18th for the First Atlantic Invest.




Already had 90L in March.
Member Since: Posts: Comments:
Quoting Some1Has2BtheRookie:



We have nothing to fear but, fear itself. Or, as Grothar once said, "I bring my own fear!".
and its name is mrs. Grothar
Member Since: July 15, 2006 Posts: 168 Comments: 53285
European news reports:-

Over 10 people killed and over 100 injured in severe sand storms in Germany.
The sand storms blocked visibility on motorways and traffic which is not speed restricted on some motorways was involved in pile ups.
Apparently these sandstorms are not uncommon in Germany. Makes you wonder why they don't have speed limits? That may affect fast car sales, of course!!
Member Since: Posts: Comments:
Quoting RastaSteve:


Yeah Accuweather is expecting a huge outbreak with 50 to 70 tornadoes. I'm sure we will be seeing photos of some F3 and F4 wedge tornadoes on the news this weekend.



ehhh its Accuweather, I'm not sure if you wanna go to them for valid scientific information. They would be much better at making weather disaster movies for hollywood.
Member Since: Posts: Comments:
Quoting Grothar:


All I want to know is where do you get a copy of my high school picture?? LOL


The internet is a wonderful thing. Wow, I thought it was a old college photo from a frat party or something
Member Since: August 7, 2010 Posts: 0 Comments: 1933
TampaTom, what venue are you going to be teaching at?
Member Since: August 7, 2010 Posts: 0 Comments: 1933
Quoting Grothar:



You mean it stood out because the temperatures were in the low 20's or you are in your low 20's????
The temps are in the low 20s. I'm well past my low 20s. Not quite as advanced as your ancientness, but definitely past the low 20s.
Member Since: Posts: Comments:
Joe Bastardi has great site at WeatherBell!He predicted 20 storms last year and nailed it!
Member Since: Posts: Comments:
Quoting emcf30:



yea about 50 years ago, oh wait, we did not have computers back then


All I want to know is where do you get a copy of my high school picture?? LOL
Member Since: Posts: Comments:
Quoting jeffs713:
I know it is a highly variable area, due to its shallowness, but it just stood out at me being in the low 20s.



You mean it stood out because the temperatures were in the low 20's or you are in your low 20's????
Member Since: Posts: Comments:
Quoting Grothar:


Here is emcf30 trying to reach the F5 key. Go ahead, make my day. LOL



Quoting Grothar:


Here is emcf30 trying to reach the F5 key. Go ahead, make my day. LOL




yea about 50 years ago, oh wait, we did not have computers back then
Member Since: August 7, 2010 Posts: 0 Comments: 1933
Quoting Patrap:


2011 National Hurricane Conference

April 18-22|Hyatt Regency Atlanta|Atlanta, GA

The nation's forum for education and professional training in hurricane and disaster preparedness!



Purpose of the Conference

The primary goal of the National Hurricane Conference is to improve hurricane preparedness, response, recovery and mitigation in order to save lives and property in the United States and the tropical islands of the Caribbean and Pacific. In addition, the conference serves as a national forum for federal, state and local officials to exchange ideas and recommend new policies to improve Emergency Management.

To accomplish these goals, the annual conference emphasizes:



* Lessons Learned from Hurricane Strikes.

* State of the art programs worthy of emulation.

* New ideas being tested or considered.

* Information about new or ongoing assistance programs.

* The ABC's of hurricane preparedness, response, recovery and mitigation -- in recognition of the fact that there is a continual turnover of emergency management leadership and staff.



I'll be there! Teaching, in fact...
Member Since: Posts: Comments:
Quoting Patrap:
TCHP





Thank Goodness last year the loop current wasn't running into the Gulf during Deepwater spill. It would have brought all that oil to the Keys and the reefs.
Member Since: Posts: Comments:
Well have a nice weekend you'll. Repeat history channel has great 1935 hurricane special on right now. It's covering other aspects about the times back then and the treatment of the ww1 vets. It's amazing how true the saying is history always repeat itself.
Member Since: Posts: Comments:
Quoting Grothar:


It is normally cool around the big bend area. Things should heat up soon.
I know it is a highly variable area, due to its shallowness, but it just stood out at me being in the low 20s.
Member Since: Posts: Comments:
WAVETRAK - Northern Atlantic Sector
Member Since: Posts: Comments:
We have had invest in May for how many years in a row now?
Member Since: Posts: Comments:
Quoting jeffs713:
Well, the Loop Current is extremely.. uh.. "prominent". Of some note is the cold pools near the upper TX coast and also around the big bend area.


It is normally cool around the big bend area. Things should heat up soon.
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Quoting Patrap:
Am going with May 18th for the First Atlantic Invest.



So blobcasting will start around... tomorrow?
Member Since: Posts: Comments:
Am going with May 18th for the First Atlantic Invest.


Member Since: Posts: Comments:
Quoting Grothar:
Interesting about the Gulf.

Well, the Loop Current is extremely.. uh.. "prominent". Of some note is the cold pools near the upper TX coast and also around the big bend area.
Member Since: Posts: Comments:
Quoting Jedkins01:


I don't know, I can imagine dry Tortugas can actually be quite wet at times. That part of the gulf can be absolutely drenched with rain sometimes. Its just that it's April on an island off the coast of South Florida.

I would probably bet dry Tortugas is known for some huge rain events at times actually. People probably just visited it during the winter and spring and called it "dry Tortugas".


No, the Spanish seafarers named it Tortugas because of all the sea turtles nesting on it. The "dry" was added later to denote there was no fresh drinking water available on the islands. It told other mariners that they may as well pass it up when they were searching for fresh water. Unless of course, they wanted a turtle to eat.
Member Since: Posts: Comments:
Quoting hurricane23:
Hurricane Andrew Page
I still have the publication the Miami Herald put out on Andrew with all the pictures. The lower middle and lower keys were spared, but we all had survivors guilt in one form or another. It just amazes me how people can live through the destruction that occurred.
Member Since: Posts: Comments:
Interesting about the Gulf.

Member Since: Posts: Comments:
Quoting Grothar:


Here is emcf30 trying to reach the F5 key. Go ahead, make my day. LOL

And here is Grothar not posting an image, since none of us can see it.

;)
Member Since: Posts: Comments:
Quoting Neapolitan:

I'm going to send JB the latest edition of Climate for Dummies; what he's blathering about in this video is the same stuff that's been proven time and time and time again, so perhaps he needs a simple refresher on the basics. Either he's forgotten some of this stuff, or he's intentionally lying and obfuscating; it's sometimes hard to tell.

That is unbelievable- people buy that dribble huh?
Member Since: Posts: Comments:
Quoting emcf30:


Here is emcf30 trying to reach the F5 key. Go ahead, make my day. LOL


Member Since: Posts: Comments:
Quoting Jax82:
Todays top google searches.

1. planned parenthood
2. government shutdown 2011
3. military pay
4. cspan
5. real housewives of new york

We sure do have a priorities straight here in the Ole US of A.

Link

The first 4 I get. #5... uh... wha? #6 was shocking (and a travesty), and then the rest go into the category of "huh" and "we're lame"
Member Since: Posts: Comments:
History channel has storm of the century on at this moment it's about 1935 hurricane in the Keys. Not trying to be coy here but shutter to think if that scenario ever plays out again. Will be cash building only in the Keys because there won't be any insurance.
Member Since: Posts: Comments:

Viewing: 734 - 684

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35Blog Index

Top of Page

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.