Average hurricane season foreseen by CSU, but TSR predicts an active season

By: Dr. Jeff Masters , 5:01 PM GMT on April 07, 2009

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A near-average Atlantic hurricane season is on tap for 2009, according to the latest seasonal forecast issued today by Dr. Phil Klotzbach and Dr. Bill Gray of Colorado State University (CSU). The Klotzbach/Gray team is calling for 12 named storms, 6 hurricanes, and 2 intense hurricanes. An average season has 10-11 named storms, 6 hurricanes, and 2 intense hurricanes. The new forecast is a step down from their December forecast, which called for 14 named storms, 7 hurricanes, and 3 intense hurricanes. The new forecast calls for a near-average chance of a major hurricane hitting the U.S., both along the East Coast (32% chance, 31% chance is average) and the Gulf Coast (31% chance, 30% chance is average). The Caribbean is also forecast to have an average risk of a major hurricane.

The forecasters cited several reasons for reducing their forecast from an active season to an average season:

1) Sea surface temperature (SST) anomalies in the tropical Atlantic have cooled considerably since December. In fact, these SST anomalies are at their coolest level since July 1994. Cooler-than-normal waters provide less heat energy for developing hurricanes. In addition, an anomalously cool tropical Atlantic is typically associated with higher sea level pressure values and stronger-than-normal trade winds, indicating a more stable atmosphere with increased levels of vertical wind shear detrimental for hurricanes. Part of the reason for the substantial cooling since December is because a stronger than average Bermuda-Azores High drove strong trade winds. These strong winds acted to evaporate more water from the ocean, cooling it. Higher winds also increase the mixing of cool waters to the surface from below. However, in March, the Bermuda-Azores High weakened. The resulting weaker trade winds may allow SSTs to warm to above average levels by the coming hurricane season, if this weaker Bermuda-Azores High persists.

2) Hurricane activity in the Atlantic is lowest during El Niño years and highest during La Niña or neutral years. The CSU team expects current weak La Niña conditions to transition to neutral and perhaps weak El Niño conditions (50% chance) by this year's hurricane season. April and May are typically the months when the atmosphere will swing between El Niño and La Niña, which makes any seasonal forecasts of hurricane activity during April low-skill. The current computer models used to predict El Niño (Figure 1) mostly favor neutral conditions for the coming hurricane season. These models are primarily based on statistical methods that observe how previous El Niño events have evolved. Three of the newer computer-intensive dynamical models (similar to the GFS model we use to make weather forecasts) do predict an El Niño event by hurricane season. The reliability of all of these models is poor.


Figure 1. Computer model forecasts of El Niño/La Niña made in March. The forecasts that go above the red line at +0.5°C denote El Niño conditions; -0.5°C to +0.5°C denote neutral conditions, and below-0.5°C denote La Niña conditions. Three computer models predict El Niño conditions for hurricane season (ASO, August-September-October). However, most of the models predict neutral conditions. Image credit: Columbia University's IRI.

Analogue years
The CSU team picked five previous years when atmospheric and oceanic conditions were similar in April to what we are seeing this year. Those five years were 2001, featuring Category 4 storms Michelle, which hit Cuba, and Iris, which hit Belize; 1985, which had Category 3 Gloria in New England and Category 3 Elena in the Gulf of Mexico; 1976, which had Category 1 Hurricane Belle in New England; 1968, which had Category 1 Hurricane Gladys north of Tampa; and 1951, which had only one landfalling hurricane, Category 3 Hurricane Charlie in Mexico. The mean activity for these five years was 11 named storms, 7 hurricanes, and 3 intense hurricanes.

How accurate are the April forecasts?
This year's April forecast uses the same formula as last year's April forecast, which did quite well predicting the 2008 hurricane season. Last year's forecast included the statement, "These real-time operational early April forecasts have not shown forecast skill over climatology" during the 13-year period 1995-2007. Unfortunately, this year's forecast neglects to mention this fact. In fact, when looking at 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) their April forecasts have had negative skill between 1995-2008. In other words, you would have been better off using climatology than believing their April forecasts.

2009 Atlantic hurricane season forecast from Tropical Storm Risk, Inc.
The British private forecasting firm Tropical Storm Risk, Inc. (TSR), issued their 2009 Atlantic hurricane season forecast yesterday, but they are calling for an active year: 15 named storms, 7.8 hurricanes, and 3.6 intense hurricanes. TSR predicts a 63% chance of an above-average hurricane season, 24% chance of a near-normal season, and only a 13% chance of a below normal season. They give a 63% chance that 2009 will rank in the top third of most active hurricane seasons on record. The April 2009 TSR forecast is virtually identical to their December 2008 forecast, and is also quite close to their April 2008 forecast made for the 2008 hurricane season.

I like how TSR puts their skill level right next to the forecast numbers: 11% skill above chance at forecasting the number of named storms, 9% skill for hurricanes, and 7% skill for intense hurricanes. That's not much better than flipping a coin, but is better than the negative forecast skill of the Klotzbach/Gray April forecasts.

TSR projects that 4.8 named storms will hit the U.S., with 2.1 of these being hurricanes. The averages from the 1950-2008 climatology are 3.2 named storms and 1.5 hurricanes. Their skill in making these April forecasts for U.S. landfalls is 10-15% above chance. In the Lesser Antilles Islands of the Caribbean, TSR projects 1.4 named storms, 0.6 of these being hurricanes. Climatology is 1.1 named storms and 0.5 hurricanes.

TSR cites one main factor for their forecast of an active season: slower than normal trade winds from July - September over the Main Development Region (MDR) for hurricanes over the Atlantic (the region between 10° - 20° N from Central America to Africa, including all of the Caribbean). Trade winds are forecast to be 0.4 meters per second (about 1 mph) slower than average in this region, which would create greater spin for developing storms, and allow the oceans to heat up due to reduced evaporational cooling. TSR forecasts that SSTs will be near average in the MDR during hurricane season, and will not have an enhancing or suppressing effect on hurricane activity.


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 TSR (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.

Jeff Masters

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255. That could be both good and bad in some ways Drak?
Ouote feature running OK with FF3
Member Since: July 3, 2005 Posts: 427 Comments: 129419
256. Well I don't like that what if you live next to Lizzie Bordin?
251. kmanislander

Mine's not working either.

Same here, unusually cool winter. Unfortunately, I wish ours was wetter. Haven't seen real rain in quite some time.
Member Since: September 9, 2008 Posts: 6 Comments: 3414
How long until we see stormkat?
Member Since: July 8, 2005 Posts: 259 Comments: 24548
In Southeast La. one keeps an AX or other means of escaping to ones roof from the Attic..in their Hurricane Prep Kit.


NHC recommends an ax



Member Since: July 3, 2005 Posts: 427 Comments: 129419
I have a feeling we are going to have to look closer to home for development this season. A lot of the long-range dynamic computer forecast models show a less active ITCZ and cooler SSTs near the coast of Africa.
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Hi Tampa

You are correct. Neutral conditions or weak La Nina versus a weak El Nino may be the single most important factor this year in determining how the season unfolds
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246. Seastep 3:19 PM GMT on April 09, 2009

For some reason my " quote " function does not work.

Our winter started out wetter than usual with unseasonably cool temps until about 10 days ago. In March we had temps of 68 at 6 pm which is almost unheard of. The cool snap lasted for weeks at a time and it has only been in the past few days that typical day time temps for this time of year have appeared.
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Quoting kmanislander:
245. hurricanelover236 3:18 PM GMT on April 09, 2009

Other than speculating, one cannot say with any degree of certainty this far out what the season will be like IMO. This is clear from the limited skill of a long range forecast even by the " experts "

Much can change between now and late July when the season tends to get going. In particular, if we see neutral conditions or a weak La Nina an above average season would be probable, especially since water temps in the GOM and the Caribbean will likely be quite high regardless of what they are in the open Atlantic.

Under such a scenario, while systems might be weaker before entering the Caribbean or GOM they could easily intensify quickly with the aid of high TCHP in these regions.


In the case of Bertha, Low TCHP may not be always an inhibiting factor.
Member Since: July 8, 2005 Posts: 259 Comments: 24548
Just curious -
What is the strangest item on your hurricane shelf or in your hurricane kit?

Throughout the winter/spring, I collect books to go on my shelf (working in a used book store, makes it easy - I just look on our quarter table). Just good old trashy novels, mysteries, thrillers etc - not reading 'War and Peace' ; ) Folks just shake their heads.

I am hoping one of you beat me in hurricane supplies weirdness - would love to show them that I am not the only one.
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245. hurricanelover236 3:18 PM GMT on April 09, 2009

Other than speculating, one cannot say with any degree of certainty this far out what the season will be like IMO. This is clear from the limited skill of a long range forecast even by the " experts "

Much can change between now and late July when the season tends to get going. In particular, if we see neutral conditions or a weak La Nina an above average season would be probable, especially since water temps in the GOM and the Caribbean will likely be quite high regardless of what they are in the open Atlantic.

Under such a scenario, while systems might be weaker before entering the Caribbean or GOM they could easily intensify quickly with the aid of high TCHP in these regions.
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Quoting kmanislander:
Good morning all

It has been interesting to see the effect that the recent cold front has had on the SST in the NW Caribbean. The water temps had been rising steadily before it but in the wake of the front's passage a significant " cool pool " has shown up in the NW Caribbean.

Given that the front did not have a cold wind in our area I can only assume that the wave action caused some upwelling.This early in the year warm water does not extend to any appreciable depth and this type of quick surface temp response to a late season front underscores that.

This cool pool will probably disappear in the next few days as stable hot conditions prevail.

Cooler than normal Atlantic water temps has been given as a reason for the reduced forecast by the Colorado Team but this far out and with several months before the peak season in which water temps can recover that factor may not necessarily play an inhibiting role.




Kman one factor in Atlantic SST is the prevailing winds. With LaNina or even Nuetral conditions, the lack of weaker than normal Westerly winds would tend to create an environment of higher SST's. We will see!
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Hey kman.

How's your winter been?
Member Since: September 9, 2008 Posts: 6 Comments: 3414
I personally think that this hurricane season is going to be extremely quiet. I think less activity than 06. Does anyone agree with me?
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Good morning all

It has been interesting to see the effect that the recent cold front has had on the SST in the NW Caribbean. The water temps had been rising steadily before it but in the wake of the front's passage a significant " cool pool " has shown up in the NW Caribbean.

Given that the front did not have a cold wind in our area I can only assume that the wave action caused some upwelling.This early in the year warm water does not extend to any appreciable depth and this type of quick surface temp response to a late season front underscores that.

This cool pool will probably disappear in the next few days as stable hot conditions prevail.

Cooler than normal Atlantic water temps has been given as a reason for the reduced forecast by the Colorado Team but this far out and with several months before the peak season in which water temps can recover that factor may not necessarily play an inhibiting role.

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Did anyone participate in the Hurricane Futures Market? Not sure if it still exists, but a very interesting "pay for prediction" senario done by a few schools.
Link

For the record, I am not the author of the posted comment at the bottom of the atricle. Albeit, I am not sure if I dissagree with it.
Member Since: June 12, 2005 Posts: 6 Comments: 8188
Quoting CybrTeddy:
warmed up a good 20 degrees in the past 2 hours. 71.3 now


Is it safe to assume you are logging everyones predictions so we can declare a winner in December ? BTW, what is the prize ? :¬)
Member Since: June 12, 2005 Posts: 6 Comments: 8188
warmed up a good 20 degrees in the past 2 hours. 71.3 now
Member Since: July 8, 2005 Posts: 259 Comments: 24548
Haiti's hurricanes caused $1 billion in damage

By EDITH M. LEDERER – 2 days ago

UNITED NATIONS (AP) — Haiti's impoverished economy has been battered by $1 billion in damage from last year's hurricanes and a drop in money transfers from Haitians working abroad caused by the global financial crisis, the top U.N. envoy to the Caribbean nation said Monday.

Ahead of next week's donors conference in Washington, Hedi Annabi told the U.N. Security Council that continued humanitarian aids is critical to ensure many Haitians get enough food and are able to send their children to school.

He said international assistance also is needed to generate immediate jobs as well as longer-term development to help Haiti escape its plight as the Western Hemisphere's poorest country.
Member Since: July 3, 2005 Posts: 427 Comments: 129419

Fla. lawmakers 'waking up' to insurance failures

State lawmakers are abandoning long-held promises to lower rates for hurricane policies -- even amid the prospect of stronger storms -- in favor of rapid hikes to rescue public insurance programs that could sink, financially speaking, during the looming cyclone season.
Member Since: July 3, 2005 Posts: 427 Comments: 129419
i can't ask for a more beautiful morning here in Delray beach fl! Figures since my time off is over and i go back to work :(
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78 degrees and not a cloud in the sky here on the beach in sarasota........there goes the cool weather until next fall(waving towards the North).....
Member Since: October 5, 2007 Posts: 20 Comments: 4970
Complete Blog Refresh, with New Weather/CritterCam
Mirror Site
Current Home weather station data.

Daily Area of Interest
Member Since: October 1, 2007 Posts: 81 Comments: 26512
Check this out. Technology is changing everything. Here is a link to the India/Pakistan border earthquake from today. Zoom in. You can see the epicenter location noted and you can actually see a small city in close proximity to it by paning the map accordingly. The city is on the left. Also included is the link to the same for the central Italy quake from a few days ago, city on the right on that one. Amazing, this is public info, think of what is secret! Similar tools were used after Katrina to expedite the assessment of what happened.




If you really want to get a feel for how this Sat stuff works. Look at Zillow.com and put your address in and use the birds eye view. Not only will it tell you how much your house has gone down in price,LoL, you can see things on your property that will open your eyes. I could actually see in my garage and that is only a realestate site.

India/Pak

Italy
Member Since: June 12, 2005 Posts: 6 Comments: 8188
post 181 your saying at the we are at the end of a cat 5 cycle but you also theorized that the duration of this supposed cycle is affected by the AMO since were close to the peak I guess the cat 5 duration might last 1-2 years longer so I'll stay with 40%
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Suppose to be in the lower 80s in florida for a high, drastic warm up today and tomorrow.
54 degrees now.
Member Since: July 8, 2005 Posts: 259 Comments: 24548
Quoting KoritheMan:


I don't have faith in his December and April forecasts, but his May forecasts seem to be much more accurate, since by that time, we have a general idea (usually; there are exceptions, such as 2005, where an average season was predicted, similar to this year, and we had the most active season on record) of what the weather pattern is going to be like throughout a good portion of the hurricane season. This usually includes the most important factor for the season, ENSO. By May, we can usually predict with reasonable accuracy how ENSO will affect the season, barring any rapid and significant changes over the span of just a few months (i.e., 2006's rapid transition to El Nino in September, as well as 2005's transition to weak La Nina conditions during October).


Agreed, and things can change in a month. Right now all the models are saying Cool/Warm Neutral.
Member Since: July 8, 2005 Posts: 259 Comments: 24548
227. P451
Italy still rumbling away.
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226. HadesGodWyvern (Mod)
India Meteorological Department

Chief Meteorological Forecast (0000z 09APR)
==============================
A low pressure area is likely to form over south Bay of Bengal around 12th April.

Tropical Cyclone Outlook (0600z 09APR)
========================================
Convective clouds are seen over parts of southeast Arabian Sea, Comorin Area, south Bay of Bengal, and south Andaman Sea

High Sea Forecast (0900z 09APR)
================================
A trough of low a sea level lies over southwest Bay of Bengal and adjoining Sri Lanka

Member Since: May 24, 2006 Posts: 52 Comments: 46527
Quoting Bobbyweather:
Umm.. come join my 2009 AHS contest for those who are interested in tropical cyclones.



Posted.
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224. HadesGodWyvern (Mod)
tampa ya 5.2.

looks like the North Pacific tried to match it (west of Oregon) with a 4.2.
Member Since: May 24, 2006 Posts: 52 Comments: 46527
223. HadesGodWyvern (Mod)
Fiji Meteorological Services
Tropical Disturbance Summary
TROPICAL DISTURBANCE FIFTEEN-F
18:00 PM FST April 9 2009
=================================

At 06:00 AM UTC, Tropical Disturbance 15F (1004 hPa) located at 8.0S 163.0E is reported as moving slowly. Position POOR based on multispectral infrared imagery with animation and peripheral observations.

The system lies embedded along a monsoonal trough. Deep convection is mostly associated with a convergence zone to the north of 15F with organization has improved slightly. CIMMS indicates the system lies in a low shear environment under a diffluent region. Sea surface temperature is around 31C. Latest water vapor imagery shows dry air to the south. Most global models has picked up the system and moves it southwest with little intensification.

POTENTIAL FOR TD15F TO DEVELOP INTO A TROPICAL CYCLONE WITHIN THE NEXT 24 TO 48 HOURS IS LOW.
Member Since: May 24, 2006 Posts: 52 Comments: 46527
Umm.. come join my 2009 AHS contest for those who are interested in tropical cyclones.

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Quoting ajcamsmom2:
I have no faith in Dr. Gray's predictions...


I don't have faith in his December and April forecasts, but his May forecasts seem to be much more accurate, since by that time, we have a general idea (usually; there are exceptions, such as 2005, where an average season was predicted, similar to this year, and we had the most active season on record) of what the weather pattern is going to be like throughout a good portion of the hurricane season. This usually includes the most important factor for the season, ENSO. By May, we can usually predict with reasonable accuracy how ENSO will affect the season, barring any rapid and significant changes over the span of just a few months (i.e., 2006's rapid transition to El Nino in September, as well as 2005's transition to weak La Nina conditions during October).
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thanks storm!!!,good night (for real this time) everyone!!!
Member Since: October 5, 2007 Posts: 20 Comments: 4970
can anyone recommend a good meteorology book????,with all the basic science of weather,kinda a weather bible of sorts????,if there are any out there.....
Member Since: October 5, 2007 Posts: 20 Comments: 4970
good night all ,don't forget to color your eggs for easter......does anyone like "fishsticks"????
Member Since: October 5, 2007 Posts: 20 Comments: 4970
More communication, education needed in hurricanes

By JACKIE STONE Associated Press Writer © 2009 The Associated Press
April 8, 2009, 6:53PM


AUSTIN, Texas — Graphics that show the risk of storm surges are just one way officials and emergency responders hope to better prepare themselves and coastal residents for the 2009 hurricane season.

Bill Read, director of the National Hurricane Center, said at the National Hurricane Conference on Wednesday that most coastal residents have a hard time understanding storm surge risk and the center didn't communicate the threat well during Ike, which stormed ashore in Galveston in September.
Member Since: July 3, 2005 Posts: 427 Comments: 129419
SRQ,siesta key to be exact.....right on the beach.even have myself a little view of the GOM from my balcony on the 3rd floor!!!!
Member Since: October 5, 2007 Posts: 20 Comments: 4970
Quoting HadesGodWyvern:
Magnitude 4.5
Date-Time Thursday, April 09, 2009 at 03:14:52 UTC
Thursday, April 09, 2009 at 05:14:52 AM at epicenter

Location 42.412°N, 13.419°E
Depth 5 km (3.1 miles) set by location program
Region CENTRAL ITALY


Did you see that large Quake in the Atlantic today....WOW!
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212. HadesGodWyvern (Mod)
Magnitude 4.5
Date-Time Thursday, April 09, 2009 at 03:14:52 UTC
Thursday, April 09, 2009 at 05:14:52 AM at epicenter

Location 42.412°N, 13.419°E
Depth 5 km (3.1 miles) set by location program
Region CENTRAL ITALY
Member Since: May 24, 2006 Posts: 52 Comments: 46527
StormW you got mail!
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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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