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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On the eve of a possible government shutdown, hundreds of thousands of federal workers and members of the military are at risk of not collecting a paycheck until after Congress reaches a deal to fund the government.
But as of now, the people directly involved in bringing about a shutdown -- members of Congress -- will still continue to receive their pay as scheduled even if scores of other workers are furloughed.
Damn if they don't pay the military. That's messed up.
Deputy Secretary of Defense William J. Lynn III Message to DOD Workforce on Potential Government Shutdown
Excerpt:
“If the government shuts down due to the absence of funding, the DoD will have no funds to pay military members or civilian employees for the days during which the government is shut down. However, both military and civilian personnel will receive pay for the period worked prior to the shutdown. Military personnel, and civilians occupying excepted status positions and required to work, are entitled to be paid for work performed during the shutdown, and will be paid retroactively once the department receives additional funding. Congress would have to provide authority in order for the department to retroactively pay non-excepted employees for the furloughed period.
“Military retirees and annuitants are not paid from annually appropriated funds, and therefore their benefits should continue without interruption.
Check out the bird rising just north of Lake O this morning.
What ever happened to compromise? Isn't compromise one of the ideals this country was founded upon? Are the insolent children in Congress actually so full of themselves that they refuse to even consider compromise, and would rather put the health of the economy at risk over a talking point? Seriously?
Don't they realize that the difference in the cuts they are seeking (roughly $30 billion) is a drop in the bucket compared to our deficit? And something less than a drop in the bucket for our entire economy? What Congress is doing is akin to an office employee refusing to work because they don't have a scanner on their desk. Most companies I know of, if you pulled that, you would be looking for a new job that afternoon.
Its a travesty.
yeah, but "retroactive" don't fly with mortgage companies.
I was watching the house debate and vote yesterday, the military will get paid i'm pretty sure. By the way, did you know each house representative makes $174,000 a year?
The WPB TDWR radar had several of the "poofs" this morning too.
And dangerous... look up Roman history. Soldiers always got paid first. For a good reason.
He who has the guns makes the rules. ;)
IMO, Congress shouldn't get paid, and they should not be allowed to leave their offices and the Capitol area until something is hammered out. No weekend visit to the family, no trips back home. They don't get it fixed, they don't get any fun.
I agree. and IMO, its not congress that is the root of the problem. They are just the symptom. The root is corporate lobbying. The only people who don't understand that lobbying is, in effect, legal bribery is the people who are being lobbied. Lobbying has nothing to do with making government more transparent, or empowering the will of the people. Lobbying is all about making a single viewpoint the dominant one. Its a collection of single-issue voters, who could care less about everything else.
"I was actually saving up for a Caribbean cruise, but that money may actually be used to live on. It's certainly more important to make sure we can get the bills paid and provide for our family," he said.
but still, saving is always better than spending.
Congress will keep working during the shutdown. I agree they shouldn't be paid but they will be working. Our President, on the other hand....
At the very least, by midnight tonight, they should be able to pass a temporary measure that funds military payroll and freezes Congressional pay during any shutdown.
...and the overhead shots clearly showed the wreckage from the magnitude9.1earthquake as I shifted the map and zoomed in.
I'm impressed. Didn't realize that GoogleMaps updated their satellite photos so frequently.
I'll be amazed if there has been much more turnover than usual, which is typically about 15%. This means that 85% of the same people that have betrayed out trust so many times we can't count are sill in office! From what I've heard, most of the turnover will have occurred because about 40 people decided to retire.
Once the results are final I'll bet, of all the incumbents that ran, most of them got to keep their jobs. Even if there is a bit more turnover than usual, we still threw away another golden opportunity to hold them ALL accountable. WE wasted yet another chance to FIRE THEM ALL!
In the next election the powers-that-be will do their best to fixate everyone's attention on the totally controlled presidential race. Most everyone will ignore the heart of the problem, the Congress and become all caught up in the presidential contest. The powers-that-be will once again con everyone into believing the most important thing is who the El Presidente is. Folks, it's a CON. The Congress has more power than the executive branch and . . .
The President has no Constitutional authority to do most of the things they claim they can do. They can only ask the Congress to do what they want. The Congress could have stopped everything that's happening; the wars, the Wall Street takeover, the TRILLION DOLLAR defense budget they just passed. Our so-called representatives have sold us out so many times it makes my head spin and what do we all do? We not only let them keep their jobs, but you watch, they will most likely give themselves a raise, like they always do, for the fine job of screwing us they've done over the last two years. The way we hold our representatives accountable is to let them keep their $174,000 a year jobs so they can stick it to us for another two years! In case you're wondering, that's $14,500 a month! And you watch. One of the first things they will probably do in the next Congress is to give themselves another raise! Last time they immediately gave themselves a $4,500 a year raise. When was the last time you got a raise like that?
Listen. If we are ever going to get a grip on our government, we're going to have to start acting like the employers that we are. The Congress critters work for US, not the central bankers and transnational corportions. What would you do If you owned a company and none of your employees listened to you, they lied to you, didn't do the jobs you gave them to do, and in fact, were actually working for your competition and selling your company down the river as fast as they could? I don't think you'd keep them on and give them a raise!
Well, that's exactly what we've been doing, only in this case, your company is our Federal Government, and your employees are the 435 members in the House of Representatives and the 100 members of the Senate, virtually all of them working for the transnational corporations (the competition) and they have already achieved a hostile takeover of our government on every level and are using the powers of our own government against us in order to take over our entire nation.
What the heck happened to that thing called "the wisdom of the American people?" You don't reward employees that betray you. YOU FIRE THEM! It's the most obvious and immediate remedy. And you don't worry that their replacement may turn out to be as bad. In fact, it's much less likely the replacements will be as bad when they know you will not tolerate such things, that you will not hesitate to fire anyone that lies and betrays your trust. Employees are far more likely to toe the line and actually do their jobs as best they can when they know they can't get away with anything less.
Of course, no analogy is perfect. This one breaks down in the sense that a company couldn't actually fire everyone all at once unless the entire company shut down. Lucky for us, our Congress isn't engaged in actually producing goods or services (the bureaucracies Congress has set up handle all government services). All Congress does is enact laws and authorize spending. It's just the legislative branch of government. We could easily go without any new laws authored by "corporate/special interest" for quite some time. So in this case, firing a large number of traitorous Congressional employees is imminently doable and quite frankly is the only thing we can do to slam the brakes on the corporate driven freight train that is railroading all of us into a nation ruled by corporate colonialism.
There are people we have elected to Congress who have been there 10, 20, 30, 40, even over 50 years! Our Congress has been betraying our trust and selling us out for generations. They not only suffer no consequences for what they've done; they've benefited greatly from their wheeling and dealing. They take an oath to protect our best interests and defend our rights as guaranteed by the Constitution and Bill of Rights, and yet they make a mockery of that oath.
$111.56 1.26
They're quick, alright; they actually updated the maps for the tsunami zone within three days of the quake.
Yeah, you could do that. Or you could talk about weather here; nobody will try to stop you. I promise. ;-)
They normally don't update them this often, but they will rush localized updates in after major events like natural disasters. They did the same thing for Haiti and Ike.
DAY 3 CONVECTIVE OUTLOOK CORR 1
NWS STORM PREDICTION CENTER NORMAN OK
0246 AM CDT FRI APR 08 2011
VALID 101200Z - 111200Z
...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF SE
MN...WI...ECNTRL IA...NW IL AND FAR NE MO...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE UPPER MS
VALLEY...MID-MS VALLEY...OZARKS AND SRN PLAINS...
CORRECTED TO EXTEND MDT RISK AREA FURTHER INTO SE MN AND NRN IA TO
MATCH PROBABILITIES
...UPPER MS VALLEY/WRN GREAT LAKES...
AN IMPRESSIVE UPPER-LEVEL TROUGH IS FORECAST TO MOVE INTO THE CNTRL
PLAINS SUNDAY WITH AN UPPER-LEVEL LOW CLOSING OFF OVER THE NRN
PLAINS. AHEAD OF THE SYSTEM...A POWERFUL 55 TO 70 KT JET WILL
TRANSPORT LOW-LEVEL MOISTURE QUICKLY NWD INTO THE UPPER MS VALLEY
WHERE SFC DEWPOINTS SHOULD REACH THE LOWER TO MID 60S F. THIS SHOULD
ALLOW MODERATE INSTABILITY TO DEVELOP ACROSS MUCH OF THE UPPER
MIDWEST BY SUNDAY AFTERNOON WHERE NUMEROUS THUNDERSTORMS APPEAR
LIKELY TO DEVELOP AS LARGE-SCALE ASCENT INCREASES DURING THE
AFTERNOON. THUNDERSTORMS SHOULD FIRST DEVELOP DURING THE AFTERNOON
ALONG A WARM FRONT ACROSS IA...WI AND SRN MN WITH ADDITIONAL
CONVECTION INITIATING ALONG THE COLD FRONT DURING THE EARLY EVENING
EXTENDING SWD INTO NW MO. THIS IS EXPECTED AS THE EXIT REGION OF THE
AN IMPRESSIVE 80 TO 100 KT MID-LEVEL JET SPREADS ACROSS THE
UPPER-MIDWEST CREATING STRONG DEEP LAYER SHEAR AND VERY FAVORABLE
CONDITIONS FOR SEVERE STORMS. THIS COMBINED WITH STRONG LOW-LEVEL
SHEAR PROFILES SHOULD BE FAVORABLE FOR SUPERCELLS AND TORNADOES
ESPECIALLY IN ERN IA...NW IL...SE MN AND SW WI WHERE A MODERATE RISK
HAS BEEN PLACED. A FEW STRONG TORNADOES COULD OCCUR EITHER NEAR THE
WARM FRONT IN THE AFTERNOON OR ALONG THE COLD FRONT AS THE LOW-LEVEL
JET STRENGTHENS DURING THE EARLY EVENING.
AT THIS POINT...THE MODELS APPEAR TO BE IN GOOD AGREEMENT CONCERNING
THE TIMING AND STRENGTH OF THE SYSTEM. ALTHOUGH THIS IS THE
CASE...AM EXPECTING THE UPPER-LEVEL TROUGH TO BE A BIT SLOWER INTO
THE PLAINS SO HAVE NUDGED THE MODERATE RISK A BIT SWWD TO ACCOUNT
FOR THIS.
...SRN AND CNTRL PLAINS...
AN IMPRESSIVE UPPER-LEVEL TROUGH WILL MOVE INTO THE GREAT PLAINS
SUNDAY. THUNDERSTORM DEVELOPMENT WILL BE PROBABLE AHEAD OF THE
TROUGH ALONG A COLD FRONT FROM ERN KS SWD INTO ERN OK AND ECNTRL TX
WHERE MODERATE INSTABILITY AND STRONG DEEP LAYER SHEAR IS FORECAST.
DUE THE POTENTIAL FOR SUPERCELL DEVELOPMENT...AN ENHANCED THREAT FOR
TORNADOES...LARGE HAIL AND WIND DAMAGE COULD OCCUR DURING THE EARLY
EVENING FROM WCNTRL MO SWD INTO NW AR AND NE OK. THE THREAT SHOULD
BE MORE ISOLATED IN SE OK AND ECNTRL TX BUT THE ENVIRONMENT SHOULD
STILL SUPPORT HAIL AND WIND DAMAGE.
...UPPER OH VALLEY AND CNTRL APPALACHIAN MTNS...
ISOLATED THUNDERSTORM DEVELOPMENT ALSO MAY OCCUR JUST TO THE EAST OF
AN UPPER-LEVEL RIDGE IN THE UPPER OH VALLEY AND CNTRL APPALACHIAN
MTNS. IN THIS REGION...MODELS FORECAST AN AXIS OF MODERATE
INSTABILITY WITH ENOUGH DEEP LAYER SHEAR FOR A MARGINAL SEVERE
THREAT MAINLY SUNDAY AFTERNOON.
..BROYLES.. 04/08/2011
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And the effect of federal workers having to cutback on spending -- with no paycheck in sight -- is going to send ripples of cutbacks in workhours and lower pay into a large portion of the service sector. So those loan triggers will also be pulled on private-sector workers.
Decisions, decisions.
My niece was born the day Andrew hit. The low peasure induced early labor and she was 1.5 pounds when she was born, 3 months early. Her father drove through the early part of the storm to get to the hospital. When He got there they would not let anyone in and He had to ride the storm out in the parking garage.
I don't agree with ALL of it, but I do agree with the jist of it. The American public has had the wool pulled over its eyes every 2 years, and especially so every 4 years. The American voter, in general, does not remember what happens 6 months before the election. We remember what happened last week. We remember what the candidate said in the last debate 3 weeks ago. We don't remember that they voted to reduce school funding, or voted against that healthcare bill. Or held up a college funding bill over a trade proposal that would cost a corporate donor a few million in sales. We don't remember that. All we see is what the talking heads on TV say in a 20-second sound bite, or what some divisive editorial writer says.
We don't vote based on the best candidate any more. We don't vote based on who we think will represent our ideals the best. We vote based on a vague party platform. We vote on rhetoric. We vote based on what the candidate says, knowing full good and well they are lying about 80% of what they say, and the other 20% they can't do on their own anyway.
In the past 30 years, our country has effectively been stuck in neutral (sometimes first gear). We've made lots of talk, but little progress. Think back to 1980. What advances have come since then due to a federal government initiative?
- The internet? No, that was started by the government, but restricted to educational institutions. The government didn't make it available to the rest of the world, private parties did.
- The computer? Nope, private parties did that.
- Space exploration? Ok, we put the shuttle in space, and the ISS. That was all started before 1980, and wasn't a new initiative.
In the 30 years prior to 1980, we put men in space, put a man on the moon, and started the interstate highway system.
The US government, as a whole, is stuck into neutral because Congress figured us out. They figured out what they need to do to be re-elected without actually doing much. Since I'm seeing more evidence that we have figured them out too, we need to do something about it!
I headed a team the day after Andrew hit that set up and ran a DMAT unit on Crome ave at what was the community center in Homestead. We had delivered several babies at that center. We slept on the shuffle board courts for several days. Was an interesting experience.The damage was amazing. There was Homestead Police officers assigned with us when we started to do search and rescue. Most of the times they did not even know where we were at due to the visual landmarks and signs being wiped out. I will try to scan some photos and post them in my pics section of the website.
I wonder how many other folks at other NWS offices will be furloughed? At Norman, OK? During the spring tornado season?
The NCDC is having some server issues, so that map shows only incomplete data from April 4th, 5th, and 6th. On those days, there were 352 record daily highs (269 new, 83 ties), 86 record daily high minimums (59, 27), 80 record daily lows (42, 38), and 50 record daily low maximums (32, 18).
The map source is Ham Weather. The dot is on Dry Tortugas, its tough to see ;) On Wed, Apr 6th Dry Tortugas recorded 0.5 inches, the old record was 0.07 inches in 1954.
Here's a Link
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