Average hurricane season foreseen by CSU, NOAA, and TSR

By: Dr. Jeff Masters , 4:45 PM GMT on June 02, 2009

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A near-average Atlantic hurricane season is on tap for 2009, according to the seasonal hurricane forecast issued June 2 by Dr. Phil Klotzbach and Dr. Bill Gray of Colorado State University (CSU). The CSU team is calling for 11 named storms, 5 hurricanes, and 2 intense hurricanes, and an Accumulated Cyclone Energy (ACE) 88% of average. Between 1950 - 2000, the average season had 10 named storms, 6 hurricanes, and 2 intense hurricanes. But since 1995, the beginning of an active hurricane period in the Atlantic, we've averaged 15 named storms, 8 hurricanes, and 4 intense hurricanes per year. The new forecast is a step down from their April forecast, which called for 12 named storms, 6 hurricanes, and 2 intense hurricanes. The new forecast calls for a near-average chance of a major hurricane hitting the U.S., both along the East Coast (28% chance, 31% chance is average) and the Gulf Coast (28% 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 an average season:

1) Sea surface temperature (SST) anomalies in the tropical Atlantic are quite cool. 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. Substantial cooling began in November 2008 (Figure 1), primarily due to a stronger than average Bermuda-Azores High that drove strong trade winds. These strong winds increased the mixing of cool waters to the surface from below, and caused increased evaporational cooling.

2) Hurricane activity in the Atlantic is lowest during El Niño years and highest during La Niña or neutral years. This occurs because El Niño conditions bring higher wind shear over the tropical Atlantic. The CSU team expects the current neutral conditions may transition to El Niño conditions (70% chance) by this year's hurricane season. I discussed the possibility of a El Niño conditions developing this year in a blog posted Friday.


Figure 1. Change in Sea Surface Temperature anomaly between November 2008 and 2009. Most of the Atlantic has cooled significantly, relative to normal, over the past 7 months. Image credit: NOAA/ESRL.

Analogue years
The CSU team picked five previous years when atmospheric and oceanic conditions were similar to what we are seeing this year: neutral to slightly warm ENSO conditions, slightly below-average tropical Atlantic SSTs, and above-average far North Atlantic SSTs during April-May. Those five years were 2002, which featured Hurricane Lili that hit Louisiana as a Category 1 storm; 2001, featuring Category 4 storms Michelle, which hit Cuba, and Iris, which hit Belize; 1965, which had Category 3 Betsy that hit New Orleans; 1960, which had two Category 5 hurricanes, Ethyl and Donna; and 1959, which had Category 3 Hurricane Gracie, which hit South Carolina. The mean activity for these five years was 10 named storms, 6 hurricanes, and 2 intense hurricanes, almost the same as the 2009 CSU forecast.

How accurate are the June forecasts?
The June forecasts by the CSU team have historically offered a skill of 20 - 30% higher than a "no-skill" forecast using climatology (Figure 2). This is a decent amount of skill for a seasonal forecast, and these June forecasts can be useful to businesses such as the insurance industry and oil and gas industry that need to make bets on how active the coming hurricane season will be. This year's June forecast uses the same formula as last year's June forecast, which did quite well predicting the 2008 hurricane season (prediction: 15 named storms, 8 hurricanes, 4 intense hurricanes; observed: 16 named storms, 8 hurricanes, 5 intense hurricanes). An Excel spreadsheet of their forecast skill (expressed as a mathematical correlation coefficient) show values from 0.44 to 0.58 for their June forecasts, which is respectable.


Figure 2. Accuracy of long-range forecasts of Atlantic hurricane season activity performed at Colorado State University (CSU) by Dr. Bill Gray's team (colored squares) and Tropical Storm Risk, Inc. (TSR, colored lines). 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.

NOAA's 2009 hurricane season forecast
The National Oceanic and Atmospheric Administration (NOAA), issued its 2009 Atlantic hurricane season forecast on May 21. NOAA anticipates that an average season it most likely, giving a 50% chance of a near-normal season, 25% chance of an above-normal season, and a 25% chance of a below-normal season. They give a 70% chance that there will be 9 - 14 named storms, 4 - 7 hurricanes, 1 - 3 major hurricanes, and an Accumulated Cyclone Energy (ACE) in the 65% - 130% of normal range. The forecasters cited the following main factors that will influence the coming season:

1) We are in an active period of hurricane activity that began in 1995, thanks to a natural decades-long cycle in hurricane activity called the Atlantic Multidecadal Oscillation (AMO).

2) There will either be an El Niño event or neutral conditions in the Equatorial Eastern Pacific. An El Niño event should act to reduce Atlantic hurricane activity. However, our skill at predicting an Niño in late May/early June is poor, so there is high uncertainty about how active the coming hurricane season will be.

3) Cooler-than-average SSTs are currently present in the eastern tropical Atlantic. These cool SSTs are forecast to persist through into August-September-October (ASO). ASO SSTs in the eastern tropical Atlantic have not been below average since 1997. Cooler SSTs in that region are typically associated with a reduction in Atlantic hurricane activity.

Thus, they expect that even though we are in an active hurricane period, the presence of an El Niño or cool SSTs in the eastern Atlantic could easily suppress activity, making a near-average season the most likely possibility. They note that two promising computer models, the NOAA CFS model and the European Center for Medium-Range Weather Forecasts (ECMWF) Global Climate Model System 3, both forecast the possibility of a below-average hurricane season.

2009 Atlantic hurricane season forecast from Tropical Storm Risk, Inc.
The British private forecasting firm Tropical Storm Risk, Inc. (TSR) has joined the ranks of NOAA and Colorado State University in calling for near-average activity. The latest TSR forecast issued June 4 calls for 10.9 named storms, 5.2 hurricanes, 2.2 intense hurricanes, and an Accumulated Cyclone Energy (ACE) 72% of average. The storm numbers are close to the 50-year average of 10 named storms, 6 hurricanes, and 2 intense hurricanes, and are sharp reduction from their April forecast of 15 named storms, 7.8 hurricanes, and 3.6 intense hurricanes. TSR predicts a 50% chance that this season will be in the bottom 1/3 of years historically, and a 40% chance that U.S. landfalling activity will be in the lowest 1/3 of years historically. TSR gives a 32% chance of a near-normal season, and a 17% chance of a below normal season. TSR rates their skill level as 26% above chance at forecasting the number of named storms, 15% skill for hurricanes, and 19% skill for intense hurricanes.

TSR projects that 3.2 named storms will hit the U.S., with 1.3 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 7 - 18% above chance. In the Lesser Antilles Islands of the Caribbean, TSR projects 0.9 named storms, 0.4 of these being hurricanes. Climatology is 1.1 named storms and 0.5 hurricanes.

TSR cites two main factors for their reduced forecast: a large and unexpected cooling of sea surface temperatures in the tropical Atlantic, and warmer SSTs in the Equatorial Eastern Pacific (which might lead to an El Niño event that will bring high wind shear to the Atlantic). TSR expects faster than 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 0.83 meters per second (about 1.7 mph) faster than average in this region, which would create less spin for developing storms, and allow the oceans to cool down, due to increased mixing of cold water from the depths and enhanced evaporational cooling. TSR forecasts that SSTs will cool an additional 0.3°C compared to average over the MDR during hurricane season.

Air France crash
The Air France Flight 447 A330 aircraft that disappeared over the mid-Atlantic Ocean yesterday definitely crossed through a thunderstorm complex near the Equator, according to a detailed meteorological analysis by Tim Vasquez. He concludes that "the A330 would have been flying through significant turbulence and thunderstorm activity for about 75 miles (125 km), lasting about 12 minutes of flight time" but that "complexes identical to this one have probably been crossed hundreds of times over the years by other flights without serious incident". See also the excellent CIMSS satellite blog for more images and analysis of the weather during the flight.

Invest 92
NHC is tracking a storm near the Azores Islands (Invest 92L) that is probably the remnants of the core of an extratropical cyclone that closed off some warm air at the center. The system has developed some heavy thunderstorm activity near its center, making this a hybrid storm. However, with ocean temperatures near 62°F (16°C), this storm has little chance of becoming a named subtropical storm.

Jeff Masters

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Quoting ackee:
invest92L has 50mph winds how comes its not a subtropical or tropical system ?


NHC thinks its non-tropical and it doesn't have enough t-storm activity.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
Good Morning....Looking at the Gulf this morning, looks to me like some of the recent GFS model runs have been "overhyping" a deepening low in the Northern Gulf; the Gulf has looked very "active" for the past few days but sheer is just too much for any significant development me thinks right now..
Member Since: August 8, 2006 Posts: 0 Comments: 9413
Quoting ackee:
invest92L has 50mph winds how comes its not a subtropical or tropical system ?

Low, unorganized convection.
Member Since: December 21, 2007 Posts: 13 Comments: 3046
509. ackee
invest92L has 50mph winds how comes its not a subtropical or tropical system ?
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Quoting StSimonsIslandGAGuy:
Hey Cane :) Upon reflection, I think the Texas MCC has a better chance once it gets over the Gulf of Mexico waters.


Sorry I missed this post last night. I made my last comment and went to bed.

I am looking at the Texas MCC. It will be interesting to see what it does when its been in the GOM a few hours.
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Quoting Hurricane4Lex:
Hi all hows everyone and everything on the 3rd day of '09 AHS (Atlantic Hurricane Season)

Good, I'm going to update my blog, but I'll check the comments every so often.
Member Since: December 21, 2007 Posts: 13 Comments: 3046
There's a possibility of a
Quoting IKE:



???

@ 126 hours.

@ 132 hours.

@ 138 hours.

@ 144 hours.

@ 150 hours.

@ 156 hours.


Wait a minute... those pictures aren't surface lows, they're probably 1000 MB. So unscratch what I said in comment 501.
Member Since: December 21, 2007 Posts: 13 Comments: 3046
Hi all hows everyone and everything on the 3rd day of '09 AHS (Atlantic Hurricane Season)
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504. IKE
Quoting cg2916:

WTF? I looked at the 06Z GFS and it showed no low. So scratch comment 501.


More coffee?

Now watch it drop it on the 12Z run.

Either way, looks like an increase in moisture in the western Caribbean next week.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting IKE:



???

@ 126 hours.

@ 132 hours.

@ 138 hours.

@ 144 hours.

@ 150 hours.

@ 156 hours.


WTF? I looked at the 06Z GFS and it showed no low. So scratch comment 501.
Member Since: December 21, 2007 Posts: 13 Comments: 3046
502. IKE
Quoting cg2916:

Look at the slides before and after that. No low.



???

@ 126 hours.

@ 132 hours.

@ 138 hours.

@ 144 hours.

@ 150 hours.

@ 156 hours.

Member Since: June 9, 2005 Posts: 23 Comments: 37860
Scratch what I said about the Caribbean low in my first comment today. I don't think it will form anything. Not enough models are forecasting it. And if they do, they show a 1007/1008 MB low with very little convection with no organization or any sign of rotation for 2/3 days, not enough time for cyclogenesis.
Member Since: December 21, 2007 Posts: 13 Comments: 3046
Quoting IKE:


Latest 6Z GFS @ 120 hours....


Look at the slides before and after that. No low.
Member Since: December 21, 2007 Posts: 13 Comments: 3046
There is some model agreement with development in the WCarib next week.

Invest 92L; Heavy Rains for Gulf Coast
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Morning from Spain !

Do you know if it is possible to obtain a map with the North Atlantic SST for 1st october 1980?

Thanks.
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496. IKE
Quoting cg2916:
Alright, time for my morning review that points out the obvious.

92L - It had its chance, and blew it. Yesterday, the clouds were too disorganized. I'm surprised it even reached ST3.0 on the Dvorak. Today, we have more convection near the center, but it's more disorganized. I give it a 0% chance of becoming anything more than 92L.

Gulf Area - Unfavorable forming conditions, no low pressure center, no enter of circulation, no rotation, should be extratropical.

Possible Caribbean Low (Check the models) - Could happen, too early to tell, but keep in mind that where the models are forecasting this, there is currently a tropical wave merging with a 1007 MB low. Of course right now there's nothing there, it's a possibility.


Latest 6Z GFS @ 120 hours....

Member Since: June 9, 2005 Posts: 23 Comments: 37860
Alright, time for my morning review that points out the obvious.

92L - It had its chance, and blew it. Yesterday, the clouds were too disorganized. I'm surprised it even reached ST3.0 on the Dvorak. Today, we have more convection near the center, but it's more disorganized. I give it a 0% chance of becoming anything more than 92L.

Gulf Area - Unfavorable forming conditions, no low pressure center, no center of circulation, no rotation, should be extratropical.

Possible Caribbean Low (Check the models) - Could happen, too early to tell, but keep in mind that where the models are forecasting this, there is currently a tropical wave merging with a 1007 MB low. Of course right now there's nothing there, it's a possibility.
Member Since: December 21, 2007 Posts: 13 Comments: 3046
Invest 92L; Heavy Rains for Gulf Coast
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Tazmanian:
this year will be more like 06 where in 06 all the cold front kep moveing down too the S and out too sea this is all most the same set up for 09 the cold fronts has not let up yet they sould all so be gone by now but there not



happy hurricane season 2006 evere one go out and in joy the nic summer we will have vary little in the way of storms this year



Ever hear of Hurricane Charley taz? Well yea, 2004 had really late season cold fronts.
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Me too Tazaroo.

Nitey nite out West
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night all i leve you with this



vary rare hail in CA



000
FXUS66 KSTO 030446
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
945 PM PDT TUE JUN 2 2009

.DISCUSSION...
A COUPLE OF AREAS OF STRONG CONVECTION DEVELOPED THIS AFTN IN SHASTA
AND SW TEHAMA COUNTIES. THESE AREAS WERE IN AN AREA OF GREAT
INSTABILITY/LOWER LEVEL CONVERGENCE AND STRONG UPPER LEVEL
DIVERGENCE IN THE NE QUAD OF THE UPPER LEVEL LOW CENTER OFF THE
COAST. IN SHASTA CO...HOURLY LAPS DATA INDICATED CAPES IN EXCESS OF
1000 J/KG AND GOOD CONVERGENCE AROUND SHINGLETOWN. A STRONG STORM
DEVELOPED THERE AND MOVED TOWARDS WHITMORE. SEVERAL SPOTTERS
REPORTED 1/4 TO 3/4 INCH IN THE SHINGLETOWN AREA...SOME COVERING THE
GROUND. SHORTLY THEREAFTER...A STRONG STORM DEVELOPED NEAR
LAKEHEAD/POLLARD FLAT...WHERE WE HAD A REPORT OF SMALL HAIL AND A
POWER OUTAGE AT A GAS STATION IN THE AREA FROM THE ELECTRICAL STORM.
IN SW TEHAMA CO...THE MOST IMPRESSIVE STORM OF THE NITE DEVELOPED
NORTH OF ALDER SPRINGS. RADAR ESTIMATED TENNIS BALL HAIL
AS VILS HIT
60...THIS STORM HAD THE CLASSIC FLYING EAGLE SHAPE ON RADAR FOR
AWHILE...INDICATIVE OF MID LEVEL WINDS SPLITTING AROUND A VERY
STRONG UPDRAFT. GIVEN THE DISTANCE FROM THE RADAR...WHERE THE BASE
OF THE RADAR BEAM WAS ABOUT 10 KFT...WE WOULD EXPECT EXAGGERATED VIL
AND HAIL SIZE ESTIMATES...BUT THE LIKELIHOOD OF QUARTER SIZE HAIL OR
A LITTLE LARGER WAS CERTAINLY NOT OUT OF THE QUESTION. SINCE THIS
STORM WAS IN A VERY RURAL AREA OF THE MENDOCINO NF...WE DOUBT WE CAN
VERIFY THE SVR ISSUED FOR IT. MADE USE THIS EVENING OF THE WRH`S NEW
SPS/SWA PRODUCT AS A BRIDGE TO THE HIGHER WARNING CRITERIA WHICH
COMMENCED 6/1...AND WE GIVE A BIG THUMBS UP TO THIS PRODUCT AND THE
SOFTWARE. WE COULD GET THESE STATEMENTS OUT IN LITERALLY SECONDS.

LOOKS LIKE MORE OF THE SAME FOR INTERIOR NORCAL ON WED AS THE UPPER
LOW OFF THE COAST WILL EDGE SLOWLY EWD DURING THE DAY...MAINTAINING
THE INSTABILITY AND UPPER MASS DIVERGENCE OVER INTERIOR NORCAL.
CURRENTLY RADAR INDICATES LIGHT SHOWERS IN THE NRN SAN JOAQUIN VLY
SPREADING NWD INTO THE SRN SAC VLY...SO CAN NOT RULE OUT A SHOWER OR
ISOLATED STORM OVERNITE AND ON WED AS WELL. MODELS INDICATE SHORT
WAVE ENERGY ROTATING AROUND THE OFFSHORE LOW AND INLAND ALONG AND S
OF THE I-80 CORRIDOR WED NITE WHICH MAY RESULT IN SOME NOCTURNAL
STORMS AS WELL. THU NITE AND FRI ALSO LOOK LIKE ACTIVE WX PERIODS AS
ADDITIONAL SHORT WAVES ROTATE AROUND THE SLOWLY EWD MOVING UPPER LOW
TRIGGERING CONVECTION OVER INTERIOR NORCAL. JHM
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I guess you Missed the Smooth NOLA Gustav evacuation last August 29th..too.


News aint all its cracked up to be,...
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News is News for the fodder Orca..

People get Killed in Churches and even B.C.
Unfortunately.

Jazz Fest to Mardi Gras..we take the World in 24/7 365

Even Canadians..







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Well if your like me..and just reading the news... Murder Capital of the US, and not having a Hurricane Command Centre open for Hurricane season... does not do the city image good at all.
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St Bernard Rebuilding Webpage
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St Bernard took a terrible Hit in 05.
About 70% have returned.
Many sold ..But the Parish is a strong Fishing and Refining community. Always tight knit.

Ground Breaking of Fire Station No. 11 held Friday, May 22

Old Arabi Neighborhood Association and St. Bernard Domino Sugar Refinery produces over 7 million pounds of sugar per day and is now the largest sugar refinery in the world.
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Orleans is the Parish east of Jefferson Parish.
The City Proper,Orleans Parish has 230,00 folks.
Thats the article EOC.
Jefferson Parish the western Suburb,with 5-6 Townships has 330,000 folks.
Everything aint Orleans Parish..



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Quoting Patrap:

Jefferson Parish EOC ..is a State of the Art Center and feeds the sister Orleans Parish 99% of the Time


So what is this one in the news article?
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Jefferson Parish West of NOLA is the Hub

Emergency Operating Center (EOC)
Home > Jefferson Parish Departments > Emergency Management
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New hurricane command center in New Orleans -- in disrepair...

NEW ORLEANS When hurricanes threaten emergency operations centers, or, across the state are the nerve centers for first responders and emergency managers. It's where they come together to make key decisions for public safety.......
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U.S. military spacecraft aid search for missing Airbus

U.S. Air Force Defense Support Program (DSP) missile warning satellite data collected early June 1 over the central Atlantic, is being examined to see if it captured a possibly fiery breakup or impact of the Air France Airbus A330 that disappeared enroute to Paris from Rio de Janeiro, Brazil.
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New Orleans again nation's murder capital

NEW ORLEANS (AP) - New Orleans is once again the nation's murder capital after briefly losing the title.

Fresh FBI statistics show that with 64 killings per 100,000 people in 2008, New Orleans had the highest per capita murder rate in the nation, well ahead of second-place St. Louis, which had 47 murders per 100,000 people.
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472. beell
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Quoting KEEPEROFTHEGATE:
kill what


Post 467 just brought me a dead halt... hard to load.. not sure why. I have all the power in the world.. but it sure lagged it down
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kill what
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March 6 2008 - Subtropical E ATL

Member Since: July 24, 2005 Posts: 407 Comments: 19076
KOG, you killed it
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Grrr stupid early storms are keeping me up... Really nice 99 image loop of this storm.. but its f*$#(ing java. Someone figure out how to save this please!!! Even a screen motion capture program. Please PM me if you do. i really need to leave cause i got work in 7 hours :(((((

92L 99-image java loop
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Blob(s)?
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Quoting Weather456:
Taz, thats 500 mb. I use it since I always saw it the best level to get a general idea of how upper level systems affect TC steering flow. It is also reflected in the MSLP for Sept.




oh
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The GOM Blob is in the Upper Levels.......nothing at the surface i can find.
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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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