Early 2011 Atlantic Hurricane Season Forecasts
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
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And the somewhat related Fodder caster: one who concentrates on feeding trolls.
The part just outside San Juan would be my guess...
Yeah sorry about that. I copied straight off of my browser bar. Google "Are Earthquakes Really on the Increase" and it will come up. It is two years old you are right about that. So they have changed their minds on that?
another ThirdWorld DDT vs Malaria tale of unintended consequences.
The DDT killed the mosquitoes, then villagers' roofs started caving in.
And then the number sylvatic plague and typhus infections skyrocketed.
How? Read the link.
BTW, it was the dried vines used to lash the thatching together that was eaten, not the thatching.
I saw something on NBC and CNN that said so, but I do not trust either. I have not been able to find a peer reviewed publication yet. I have been looking. From my own experience coming from CA, I have been paying pretty close attention for many years, it does seem so to me.
It just ends up being two sides arguing to two brick walls.
Interesting note... from that article:
"According to long-term records (since about 1900), we expect about 17 major earthquakes (7.0 - 7.9) and one great earthquake (8.0 or above) in any given year."
That's an avg. annual total of earthquakes >7.0 of: 18
Current 2011 count for earthquakes >7.0 is: 8
Given that it's only the 97th day of the year, if we continue to have major earthquakes at this rate we will have roughly 30 major earthquakes this year, about twice the average number.
I haven't found any studies attempting to predict what the rest of the year might be like, but I'd expect things to start quieting down soon if history is any indication. That said, even if things do calm down (and let's hope they do), the first part of 2011 has been a period of above-average earthquake activity.
It'll be interesting to see how the rest of the year pans out, but it might be a little soon to quit your job in preparation for the end of days... :)
One should vote every chance they get, if nothing else to preserve your right to bitch about what the person who won does. How can you bitch if you voluntarily gave up your right to choose and instead gave that choice to someone else?
And I never said you shouldn't vote...
Yeah I voted when I got my first chance, now I'm just questioning whether I should or not anymore, I'm 20 now, was 18 then. I'll be hitting the big 21 this October 21st
woah didn't realize you were that young! you aren't much older than me. I thought I was like an endangered species on this blog.
No, you're not. I'm only 12 1/2 years old, turning 13 in October. I'm probably the youngest here but my knowledge of hurricanes is as sharp as a knife, no intention to brag.
The April 7, 2011 earthquake near the east coast of Honshu, Japan occurred as a result of thrust/reverse faulting on or near the subduction zone plate boundary between the Pacific and North America plates.... This earthquake can be considered an aftershock of the March 11, 2011 Mw 9.0 Tohoku earthquake. The aftershock sequence of that event has been ongoing since March 11, and has included 58 earthquakes of M 6 or greater up until April 7 2011, two of which were greater than M 7 (M7.7 and M7.9, both on March 11).
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haha same here! I didn't realize you were that young either
I do.
you do pretty good here, sweety. Sorry if I was ever real harsh to you. I'll be nicer from now on.
Well I think I may see a subtropical storm well East of North Carolina about 200 hours out on the NCEP model--so at last we have an even remote chance of perhaps seeing...Arlene? It reminds me a tad bit of Ana in 2003 which also formed in April and affected Bermuda, I think.
Thanks, you were never really harsh just occosionally you kinda got a bit critizing but thats OK. I do not understand why is Grothar teased so much, however.
dang starting early
Ya but im not too arrogant about it. Some of my friends in school are always asking me what's the weather gonna be days ahead in case one of them wants to go to the beach or has a scheduled baseball practice or whatever.
16 NS, 9 HUR, 5 INT.HUR, Although I do believe that Texas, Louisiana, and the caribbean will be the JUNE/JULY/AUGUST Targets. But once you get 2-4 months down the road it gets pretty blurry... Won't be back on the blog until next week so, have a good Friday, Saturday, and Sunday.
Dean out...
I sometimes wonder what it would take to drench the coast of Belize. Last year we had a 7.2 a little closer to Belize which shook us all up but it caused no tsunami. But history tells us that Belize has been affected by tsunamis already.
Belize has a long lead of shallow water off of its coast, which is what is needed to turn short&long ocean-going tsunamis into really tall BigWaves by the time they reach then pass over the shoreline.
It would take a Caribbean earthquake that breaks the crust up and/or down to cause a tsunami. Apparently you've been lucky to only experience quakes that move the crust side-to-side.
I studied Weather in 3rd grade, and began spreading my knowledge of hurricanes ever since I started watching them(That's why my user name is Hurricane Dean) it was the first storm I ever tracked. I've also started my own hurricane site, and can free hand North/South America, Western Africa, and Western Europe vividly by memory. So i have no trouble making hurricane maps on blank paper. Actually it's really useful...
I make hurricane maps all the time. I've been tracking Hurricanes Gustav & Ike, just about every named storm in the 2008 Hurricane Season plus the very end of the 2007 season.
It is possible to change your username?
I want to change mine to reflect my location.
hahahahohohohohehehehe
Oh, sorry. ;)
USUALLY if a season is normal or not active, the waves emerge in mid-late May, If its a above average season you see the waves emerge in early May.
First Wave Emerges~
2004: May 21 El Nino
2005: May 02 Neutral
2006: May 11 El Nino
2007: May 21 Strong La Nina
2008: May 02 Neutral
2009: May 13 El Nino
2010: May 02 Strong La Nina
2011: N/A
You can't change it without creating a new account attached to a different e-mail address.
1. Then the other guys win.
2. (my opinion only) If you don't vote then you have given up all right to complain because you didn't take part in the process.
3. People have died for the right to vote, and still die to this day trying to vote in some countries.
again, just my opinion
Ben- we tease Grothar, cause he's like 92 years old. Really. But he has a good sense of humor about it. He remembers things that most of us can only read about on Wikipedia.
When he takes his meds properly, that is.
2007 was another story... I tracked only the major storms(Dean, and Felix) and the storms that hit Texas.(Erin, Humberto)
I first started following hurricanes in 2004. In 2005 my interest for hurricanes really took off--mostly because it was the biggest season in the history of the Atlantic. After 2005 though, I lost interest in hurricanes. Not really weather, I still watched the weather on tv and stuff, but I wasn't really following weather. Maybe it's because the activity was low. At any rate, 2010 kicked back up again, and I became interested again, and now here I am.
Oh dear. Okay. Thank you.
2011 April 07 23:11:09 UTC
Nah, you're not, just turned 19, it'll be my first election as well. I always check in between classes, or right before I go to bed.
What made you reach that conclusion or guess?
Company planning biggest rocket since man on moon By SETH BORENSTEIN, AP Science Writer Tue Apr 5, 11:42 pm ET
WASHINGTON -A high-tech entrepreneur unveiled plans Tuesday to launch the world's most powerful rocket since man went to the moon.
Space Exploration Technology has already sent the first private rocket and capsule into Earth's orbit as a commercial venture. It is now planning a rocket that could lift twice as much cargo into orbit as the soon-to-be-retired space shuttle.
The first launch is slotted for 2013 from California with follow-up launches from Cape Canaveral in Florida.
Space X's new rocket called Falcon Heavy is big enough to send cargo or even people out of Earth's orbit to the moon, an asteroid or Mars. Only the long retired Saturn V rocket that sent men to the moon was bigger.
Link
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