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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NEXRAD Radar
Wichita, Base Reflectivity 0.50 Degree Elevation Range 124 NMI
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There's what it looks like a small fire a few blocks away from me.
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LSU HURRICANE CENTER



The MISSION of the LSU HURRICANE CENTER is to advance the state-of-knowledge of hurricanes and their impacts on the natural, built, and human environments; to stimulate new interdisciplinary/collaborative research activities; to transfer this knowledge and technology to students and professionals in concerned disciplines; and to assist the state, the nation, and the world in solving hurricane-related problems.



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Acting Administrator Ward Speaks At The National Hurricane Conference


WASHINGTON, D.C. -- The U.S. Department of Homeland Security's Federal Emergency Management Agency (FEMA) Administrator Nancy Ward today highlighted plans FEMA has implemented to prepare for the 2009 Hurricane Season during her address at the 31st Annual National Hurricane Conference.

In her speech, Acting Administrator Ward discussed reforms and improvements in the areas of preparedness and training, logistical management, communications, disaster operations, recovery, and mitigation. She highlighted the fact that FEMA now has 236 pre-scripted mission assignments with 29 different departments and agencies to expedite disaster response. She added that the agency continues to provide regional evacuation planning support to hurricane prone states. Ward stressed how critical federal, state, territorial, tribal, and local relationships are to successful disaster response. "If we do not plan together, train together and develop policies and procedures together, from the start, we as an emergency management community will never be as effective as we should be," Ward said. "FEMA Administrator Nominee, Craig Fugate, like DHS Secretary Napolitano, recognizes just how critical this is and knows that we need to continue to improve and expand our lines of communication and engagement."

Another key focus for Mrs. Ward was the importance of public information this hurricane season. She highlighted FEMA's use of new tools and technologies, and the incorporation of social media into outreach efforts through use of YouTube, Twitter, and Facebook. "There are so many ways the public gets their information today," said Nancy. "We need to continue to seek out communications tools outside the traditional forms of media."
Member Since: July 3, 2005 Posts: 423 Comments: 128240
Afternoon everyone. Just ordered weather station #2. 7-10 days for delivery, can't wait. Is anyone with a running cam having any issues uploading images today? Warmed up rather quickly today. 47 degrees this morning and almost 85 now. Summer is on the way.
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Dow Posts Fifth Straight Week in the Black



8083.38 246.27E (3.14%) Apr 9 4:03pm ET
Open: 7839.89
High: 8087.28
Low: 7839.89

Volume: 462,029,806
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305. HadesGodWyvern (Mod)
India Meteorological Department

Chief Meteorological Forecast (0900z 09APR)
==============================
Numerical Weather Prediction models suggest that a low pressure area is likely to form over southwest Bay of Bengal around 11th leading to increase in rainfall activity along the east coast.

The low pressure area over southwest Bay of Bengal may become more marked

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Hey Storm!

From CPC this morning...

A majority of model forecasts for the Nino-3.4 region show that once ENSO-neutral conditions are reached, it will continue through the remainder of 2009. Several models indicate La Nina will continue through March-May 2009. Based on current observations, recent trends, and model forecasts, a transition to ENSO-neutral conditions is expected during April 2009.

Full update HERE
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303. N3EG
My hurricane preparedness kit consists of a house in Washington State. Thingamabobbercane missed us by 250 miles, and those who live where it hit only needed a rake to move the leaves into their neighbor's yard.
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Just remember that the generator may not be applicable until the storm passes. Sometimes it may take 12-18 hours or longer before you can run it safely.

Additionally, do the math on the consumption with those generators. I have a 4000 watt gas unit that can run 13hours on 4 gallons at half load and a 10,000 watt, used to backfeed my AC unit that uses a gallon an hour. The big boy is only used for the AC and cooking as necessary, the other powers the amenities necessary to keep everyone at peace. Keeping in mind I usually have about 20 evac's from the beach each time.

Load chart if you need it. Link
Member Since: June 12, 2005 Posts: 6 Comments: 8186
if we have a neutral La Nina, with a below normal season for the Verdes; Combine that with high SSt's near the coast, and depending on the location of the Bermuda High. What does all that mean in terminology that some bloggers here would be better formatted to undestanding?
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Quoting plywoodstatenative:
what was the seasonal conditions for 04, 05 versus what was forecasted by Gray and company?

Whats the forecast for SST's for the season as well?

On the hurricane supplies, look to Patrap and Press, they both had some serious pages on that stuff.


I think 2004 was a neutral enso and a slight El Nino towards the end, 2005 was La Nina. Don't hold me to that i think i might be wrong.
Member Since: August 12, 2007 Posts: 2 Comments: 2838
what was the seasonal conditions for 04, 05 versus what was forecasted by Gray and company?

Whats the forecast for SST's for the season as well?

On the hurricane supplies, look to Patrap and Press, they both had some serious pages on that stuff.
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Of course... as I say all this, I live near Houston... and its just as bad here. (I live on the north side of town, so I don't even get the benefit of the sea breeze.
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293. Have you seen a doctor lately? That much heat may be getting to your brain a bit. ;)
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Quoting billsfaninsofla:


You sound disappointed! Being without power is not a pleasant thing to deal with. Especially in Florida during the summer.

Especially when it's hot and humid. Then you stick to everything.
Member Since: August 12, 2007 Posts: 2 Comments: 2838
Quoting Vortex95:
Having no power is like living in a different world somtimes. Too bad that won't happen anymore, we got a generator that runs off natural gas.


You sound disappointed! Being without power is not a pleasant thing to deal with. Especially in Florida during the summer.
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Plenty of Parrot food, dehydrated veggies & fruit as well as Jerky (for us as well as the flock). Dry dog and cat chow, plenty of kitty litter. We used a solar/hand powered radio for after Ike. It still works great. Paper towels and toilet paper and disinfecting wipes. Lots of plastic trash bags.
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Quoting Seastep:
ossqss - LOL.

For the hurricane supplies, if you have kids, plenty of board games. We have a ton because we're old school like that. No wii, xbox allowed yet. Amazing how many of my kids friends come over that have virtually zero board games.. only the electronic stuff.

They love coming over and playing them.

The kids love it. Whenever we shutter up and/or power goes out, it's like camping and we all play. They think it's cool and, at the same time, alleviates their anxiety.


I don't care how old i get, nothing beats a game of monopoly and screaming at your family to sell the boardwalk. LMAO
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Hur kit new additions this year

-Rabbit ear antenna
-digital OTA TV signal converter box ( funded $40 by the gov)net $10 cost
-Portable DVD player with inputs for the converter box, used as a monitor
-one 500 watt power inverter
-one deep cycle 120ah battery (pre-charged)
-poof- several days of intermittent news updates to ease the nerves of those who need it.
Member Since: June 12, 2005 Posts: 6 Comments: 8186
we have a bunch of board games too, but it would be just my wife and i together, no kids yet.. If we just played board games we would probably come out of the hurricane divorced lol
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ossqss - LOL.

For the hurricane supplies, if you have kids, plenty of board games. We have a ton because we're old school like that. No wii, xbox allowed yet. Amazing how many of my kids friends come over that have virtually zero board games.. only the electronic stuff.

They love coming over and playing them.

The kids love it. Whenever we shutter up and/or power goes out, it's like camping and we all play. They think it's cool and, at the same time, alleviates their anxiety.
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Quoting Patrap:
Considering the unconsidered, I think Patrap popped this one up prior, what impact on our season could a significant volcanic event produce


Not I.

I dont do the Global Picture with all the fancy Ash Plume forcings.

That a climatology thing.

Im a GOM Man myself.



My bad.

I think I am indecisive, but I am really not sure. :)
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Quoting Vortex95:
Drak just want to make sure red= high wind shear?


It means anomalously higher wind shear.
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Quoting atmoaggie:


I am kinda glad that those things do not have all that much skill...after looking at that one, anyway. Hope that hopes true.


I wouldn't mind the first half of the season being blasted with shear. You're right they don't have much skill but is something to look at.
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Quoting Drakoen:
CFS shear forecast

Peak season might actually be interesting.


I am kinda glad that those things do not have all that much skill...after looking at that one, anyway. Hope that hopes true.
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CFS shear forecast

Peak season might actually be interesting.
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Considering the unconsidered, I think Patrap popped this one up prior, what impact on our season could a significant volcanic event produce


Not I.

I dont do the Global Picture with all the fancy Ash Plume forcings.

That a climatology thing.

Im a GOM Man myself.

Member Since: July 3, 2005 Posts: 423 Comments: 128240
Quoting KEHCharleston:
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.


An espresso percolator for use on my little Coleman backpacking stove. 1/3 espresso, 2/3 hot water makes a terrific cup-o-joe in a camping-type environment.

Have to support that particular chemical dependence...
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Seasonal Hurricane Prediction Scientist
Member Since: July 3, 2005 Posts: 423 Comments: 128240
Considering the unconsidered, I think Patrap popped this one up prior, what impact on our season could a significant volcanic event produce. IE, Alaska and South America with some potential for this to occur? I would assume there would be some data avialable relating to any potential correlation.
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Morning Folks.....Overall SST's in the MDR will always hit the magical 80 degree mark once the Summer hits in earnest every year (they are usually a "given" come July and August)...Agree that the ENSO conditions, during the peak of the season, per historical climatology, will play a big role so I think that the current issue on the table (given the spread between Gray and TSR, as well as every one else who will chime in in the coming months with typically inaccurate early season predictions)is whether we will have an average or slightly above average year this season...Too early to narrow down right now and certainly impossible to accurately predict several months out.....Only time will tell
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Quoting CybrTeddy:
How long until we see stormkat?


Biting my upper and lower lips......HUM!
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Well I have to get back to work now but will check in from time to time as we get closer to June 1st.

Have a great day. 4 day weekend here for Easter !
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does anyone like fishsticks????
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Quoting Vortex95:
255. That could be both good and bad in some ways Drak?



closer to home=less preperation time
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Got the " quote " feature to work finally. Luck of the draw I guess
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Quoting Vortex95:
255. That could be both good and bad in some ways Drak?


Good as in the fact less Cape Verdes,
bad that they will develop close to home like in 2005,
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Quoting Drakoen:
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.



Those two factors would, if they materialize , put a damper on the Cape Verde season. As a follow on from that, if we get few systems of any strength entering the Caribbean the water temps and TCHP here could reach very high levels and provide ideal conditions for rapid intensification of anything forming close to home.

Looks like an interesting season on tap.
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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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