Early 2011 Atlantic Hurricane Season Forecasts

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

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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.

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Cheesy Shirt!! LOL
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233. Jax82
Here is a link for the history of Oil prices, its pretty slick.

History of oil prices

wiki
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Quoting IKE:
http://www.stormw.com/

Copy and paste for his website.


Hey man did you see his T-shirt! LOL!! I can't stop laughing right now!
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Big Fight Apr 15-18 Euro vs GFS ( I like Euro more)
By Joe Bastardi



"The Atmospheric Avenger"

That is all.

Ciao.,
Member Since: July 3, 2005 Posts: 426 Comments: 129090
229. IKE
http://www.stormw.com/

Copy and paste for his website.
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Quoting hydrus:
I am sure he lurks here...Especially during hurricane season.


I bet he has a different profile and he is on this blog.
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Quoting RastaSteve:
I have a funny feeling StormW is upon us as we speak.
I am sure he lurks here...Especially during hurricane season.
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I have a funny feeling StormW is upon us as we speak.
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oh yeah baby, I cast spells and chants and charms all the time.

be afraid.
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Quoting aquak9:
well...ya'll remember how it was last year, the "hotties" and StormW...
Yes...Pimp Daddy Storm was in da house. Hope you are doing good Aqua.
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223. Jax82
Gas prices are high and going higher, and imagine if a hurricane tracks to the western gulf coast states and takes out oil rigs, then were in big trouble.
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Can anyone here tell me what happen to StormW?
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Quoting aquak9:


StormW-Caster!!


excuse me? What is a StormW Caster? Are you guys like world of war craft nerds in here or something? I mean gosh, I'm a weather nerd but forreal I don't think spells and science go together very well, what do you think?
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Quoting aquak9:
well...ya'll remember how it was last year, the "hotties" and StormW...


Pimp-Caster! LOL! I need to visit his blog and see what he a HO77ywood are up too.
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well...ya'll remember how it was last year, the "hotties" and StormW...
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Quoting aquak9:


StormW-Caster!!
O- YEAH..?.....everything in the Universe-caster....
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Quoting FLweathergirliee:
Its very nicee day in Florida! The clouds are growing and the warm humid air is here!


StormW-Caster!!
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Whats all the talk of expensive gas . I here am paying 11.50 already and i still am not complaining.
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Its very nicee day in Florida! The clouds are growing and the warm humid air is here!
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College of DuPage Meteorology
Severe Weather and Flash Flood Warnings
Note: This page will reload every 2 minutes. Warnings are listed with the most recent first.
NEW!! Click on the station ID to bring up list of recent severe weather statements.
No severe warnings in past 3 hours

Severe Warnings Issued More Than Three Hours Ago

FLASH FLOOD WARNING HONOLULU HI - PHFO 1259 AM HST THU APR 7 2011
FLASH FLOOD WARNING HONOLULU HI - PHFO 1259 AM HST THU APR 7 2011
FLASH FLOOD WARNING HONOLULU HI - PHFO 1114 PM HST WED APR 6 2011
FLASH FLOOD WARNING HONOLULU HI - PHFO 1114 PM HST WED APR 6 2011
FLASH FLOOD WARNING HONOLULU HI - PHFO 420 PM HST WED APR 6 2011
FLASH FLOOD WARNING HONOLULU HI - PHFO 420 PM HST WED APR 6 2011
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Low over Hawaii

Member Since: August 2, 2010 Posts: 21 Comments: 9874
Member Since: August 2, 2010 Posts: 21 Comments: 9874
Just had a brief and heavy but tiny sea breeze shower, so much for a 0% chance of rain! The sun is back out and its 88 and very humid, feels like early summer to me!

BTW, moisture is exactly very high at the surface, there is numerous convective cloud activity forming around here. However, the moisture is shallow and high pressure is sinking downward against any development so rain is isolated. But still, none was in the forecast at all.
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Quoting jeffs713:
I stand corrected. I didn't look at previous maps.

My apologies to RastaSteve.


No need to apologize brother! It's just weather! I posted the link so you could see but I should have posted the looped version so you could see what I was talking about.
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Complete Update







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Quoting eddy12:
hurricanejunky basically the wall design i just gave is rated for winds exceeding 155mph with 4000 pound mud {concrete}


It sounds like it. Poured and reinforced walls are the way to go.

My builder assured me that our design was good up to 155mph. The vertical garage door braces we installed supposedly make an already 130mph wind rated garage door capable of handling 180mph winds. Since garage door failure accounted for 80% of homes destroyed in Hurricane Andrew, I think protecting the garage door is a big step in fortifying the home against ravaging winds.
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Oil tops $110 after Japan suffers another blow - Apr 7 1:48pm:
Crude futures rise sharply as the outlook for the world's third largest economy is clouded further by a second major earthquake.



But don't worry... All employers are going to give us a 28% salary increase effective April 1, 2011 (COLA)
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206. IKE

Quoting aquak9:



GAS-CASTER!!!
LYSOL-CASTER!
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We love Ike on here but is know as the resident down-caster/ now gas-caster! J/K Ike we love ya it's all in good fun.
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Quoting Levi32:


He's actually not wrong...about what the GFS shows that is. It shows what appears to be a tropical low forming in the eastern Pacific around day 7 and advecting northeastward into the western Caribbean in response to a frontal system. It is definitely not the Columbian Heat Low.

I stand corrected. I didn't look at previous maps.

My apologies to RastaSteve.
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Quoting TomTaylor:

Avg price of gas in CA $4.106

Our state has the second most expensive gas, behind Hawaii.

Cheapest gas in SD (where I am from) is $3.93



Wow. All you have to do to kill this blog is to mention the high, and ever rising, gas prices.

Excellent debates on here earlier. Thoughtful and civil discussions. That is why this blog is well above the rest! Even the bickering here is more insightful than many blogs. Thank you, all!
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Quoting aquak9:



GAS-CASTER!!!
Is that the same as a gas passer? I know a lot of them LOL.
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From one of the best blogs on the Web,
"Many people noticed the halt in SciTechDaily's services from February 22nd, the day a 6.3 magnitude earthquake hit Christchurch, shaking us and our buildings with the strongest vertical acceleration yet recorded for an earth tremor (2.2g). Small wonder the city shattered...
So did information systems..."

A magnitude6.5earthquake on the Isthmus of Tehuantepec was epicentered
58miles 148.7degrees(SSE) from Coatzacoalcos
97miles 44.9degrees(NE) from Juchitan de Zaragoza

VER is Veracruz, and CUN is Cancun
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Quoting IKE:
$4.00 a gallon?

$5.00 a gallon?



  • Oil+0.87Price/barrel$109.70




GAS-CASTER!!!
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$3.69 here just outside Houston.
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Quoting StAugustineFL:


Time will tell. To be a bit more specific on my post, I was speaking in terms of the 2011 summer season in FL. States such as CA, AK, and HI will probably see $5 plus. $3.69 in my area.

Avg price of gas in CA $4.106

Our state has the second most expensive gas, behind Hawaii.

Cheapest gas in SD (where I am from) is $3.93
Member Since: August 24, 2010 Posts: 19 Comments: 4358
Quoting Levi32:


He's actually not wrong...about what the GFS shows that is. It shows what appears to be a tropical low forming in the eastern Pacific around day 7 and advecting northeastward into the western Caribbean in response to a frontal system. It is definitely not the Columbian Heat Low.



Thanks Levi32! I've been noticing this trend on the GFS for a few days now and didn't comment on it until now as it appears there must be some sort of pattern switch going to occur next week. It seems as this big high builds off the Carolinas then pressures will begin lowering in the Caribbean. Maybe that's the reason for all the convection gathering down there.
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A little snippet on GW/hurricane links from NS (sorry):

At this week's Greenhouse 2011 conference in Cairns, a swell of researchers agreed on one conclusion. Quoting Tom Knutson, co-chairman of the World Meteorological Organisation's expert team on climate impacts on tropical cyclones, The Australian reports:

'The overwhelming majority of global climate models predicted a rise in the strength of cyclones and hurricanes worldwide, but a reduction in their number, as temperatures rose'

Also at the conference was meteorologist Kevin Walsh of the University of Melbourne, who told Sydney Morning Herald that his climate models predicted a 20 per cent drop in the number of cyclones affecting Australia by 2100, but an increase of about five per cent in the strength of cyclones.

The big question, posed by Matthew Collins at Exeter University, UK, was: why?

"We can't give a lucid answer at this time," replied Knutson - which he admitted, was a concern. One clue, however, came from the modelling. Knutson said that removing carbon dioxide from the models wiped off around half of the cyclone's predicted intensity.

Speculating, Steve Sherwood at the University of New South Wales, Sydney, Australia says that since CO2 absorbs heat, more CO2 in the atmosphere could affect where, and with what intensity, water vapour is being heated over the ocean.

As for what would make cyclones happen less often: "That's something I would like to figure out," says Sherwood.

'Somehow the atmosphere will have to make it slightly harder for a hurricane to form in order to keep evaporation in balance'

Link

Nothing new, though. In essence, they don't know if the suspicion on the link between the two is correct, and even if so, why it is like that.

Weather here has been fantastic of late - even 22C (72F) in places already. Been mostly dry on the whole, same as last year, but it feels far warmer. Hopefully it's a sign of a good summer, rather than a spring mirage.
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Brent Crude Oil
$122.47 ▲0.32
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194. IKE
Oil +1.25
Price/barrel 110.08.
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Quoting RastaSteve:
GFS is continuing to indicate that something may try to form in the Caribbean over the next couple of weeks. Either way lots of rain on tap for FL starting mid next week and lasting for what maybe quite awhile.

Link below shows where the first storm of the season may take shape over the coming weeks!

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/ carib/gfs/12/fp0_288.shtml


He's actually not wrong...about what the GFS shows that is. It shows what appears to be a tropical low forming in the eastern Pacific around day 7 and advecting northeastward into the western Caribbean in response to a frontal system. It is definitely not the Columbian Heat Low.

Member Since: November 24, 2005 Posts: 635 Comments: 26684
Government shutdown on the way, gas nearing $4 a gallon, Obama on his way out next year
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Nearing $110, barrel
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WTI Crude Oil
$109.96 ▲1.13
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Also I don't cap off my gas tank like other people, I only put in a certain amount and have about 3/4ths of a tank. Some might say why dont you fill it up? because I'm not paying for that crap, I just drive friggin less!
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Money hungry Saudi's! Oil $110 per barrel! I mean really!
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Quoting RastaSteve:


I saw on the news last night about the potential for $7.00 a gallon if we don't see a stop in rising demand for oil. I heard that could come reality in 2012.


Time will tell. To be a bit more specific on my post, I was speaking in terms of the 2011 summer season in FL. States such as CA, AK, and HI will probably see $5 plus. $3.69 in my area.
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News reports say no further damage at nuclear plant, but I'm not buying that quite yet. What else could they say?
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Here's the key with gas. Go to Shell one week, go to Exxon one week, go to Chevron one week. If you spread out with different stations regardless if one is 5 cents cheaper or not you wont have to pay a large one time bill. Your billing periods are spread out this way and it's easier to pay. It works for me.
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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.

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