CSU and TSR continue to predict a near-average hurricane season

By: Dr. Jeff Masters , 3:18 PM GMT on August 04, 2009

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A tropical disturbance embedded in the Intertropical Convergence Zone (ITCZ), near 9N 35W, is moving west at about 15 mph. The heavy thunderstorm activity associated with this tropical wave has changed little over the past 24 hours, and remains disorganized. This morning's QuikSCAT pass showed a moderate wind shift, but nothing resembling an organized surface circulation. Top winds were in the 20 - 30 mph range. Strong easterly winds are creating about 20 knots of wind shear over the wave, which is marginally conducive for development. The disturbance is about 300 miles south of the Saharan Air Layer (SAL), so dust and dry air should not hinder development over the next few days.

Given the disturbance's current lack of organization, combined with the presence of 20 knots of wind shear, any development should be slow to occur. The forecast wind shear along the storm's path over the next five days is predicted to remain at or below 20 knots, which should allow some slow development. Sea surface temperatures (SSTs) will warm from about 28°C to 29°C as the storm progresses westward. The GFS model has been indicating some development is possible in several of its runs over the past few days, but has not been consistent with this prediction. None of the other models show any development of the system. NHC is giving the disturbance a low (less than 30% chance) of developing into a tropical depression over the next two days, which is a good forecast. The GFS and ECMWF models predict the system will be approaching the northern Lesser Antilles Islands by Sunday. Both models forecast the development of a band of very high wind shear just to the north of the islands at that time, so the long-range survival of anything that might manage to develop is in doubt.

CSU forecast team continues to predict an average hurricane season
A near-average Atlantic hurricane season is on tap for 2009, according to the seasonal hurricane forecast issued August 4 by Dr. Phil Klotzbach and Dr. Bill Gray of Colorado State University (CSU). The CSU team is calling for 10 named storms, 4 hurricanes, and 2 intense hurricanes, and an Accumulated Cyclone Energy (ACE) 83% 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 June forecast, which called for 11 named storms, 5 hurricanes, and 2 intense hurricanes. Their April forecast 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 (27% chance, 31% chance is average) and the Gulf Coast (26% chance, 30% chance is average). The Caribbean is also forecast to have an average risk of a major hurricane (37%; 42% is average).

The forecasters noted that while sea surface temperature anomalies have increased in the tropical Atlantic and surface pressures have fallen in recent weeks, which normally would favor higher hurricane activity, the presence of El Niño conditions in the Eastern Pacific should counteract these influences. They forecast that the current weak El Niño event will strengthen to a moderate event by September:

El Niño events tend to be associated with increased levels of vertical wind shear and decreased levels of Atlantic hurricane activity. Tropical Atlantic sea surface temperatures anomalies have warmed somewhat since our early June prediction and surface pressures have fallen somewhat. But, the negative influences of El Niño-induced strong Caribbean Basin and Main Development Region vertical wind shear typically dominate over surface pressure and sea surface temperature in the tropical Atlantic.



Figure 1. Change in Sea Surface Temperature anomaly (in °C) between July 2009 and May 2009. Most of the tropical Atlantic has warmed, relative to normal, over the past 2 months. Image credit: NOAA/ESRL.

Analogue years
The CSU team picked four previous years when atmospheric and oceanic conditions were similar to what we are seeing this year: weak to moderate El Niño conditions, and average tropical Atlantic and far northern Atlantic SSTs. Those four years were 2002, which featured Hurricane Lili that hit Louisiana as a Category 1 storm; 1965, which had Category 3 Betsy that hit New Orleans; 1963, which had Category 4 Hurricane Flora that devastated Cuba; and 1957, which didn't have any hurricanes that hit hit land during the peak part of hurricane season. The mean activity for these four years was 9 named storms, 4 hurricanes, and 2 intense hurricanes--almost the same as the 2009 CSU forecast.

How accurate are the August forecasts?
The August forecasts by the CSU team have historically offered a skill of 45 -62% higher than a "no-skill" forecast using climatology (Figure 2). However, they are using a new forecast scheme this year, so it is difficult to judge how skillful this year's forecast might be.


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.

August 2009 Atlantic hurricane season forecast from Tropical Storm Risk, Inc.
The British private forecasting firm Tropical Storm Risk, Inc. (TSR) also issued a new forecast today, and have increased their numbers by 20% from their June and July forecasts. TSR is also calling for a near-average season, predicting 12.6 named storms, 6.5 hurricanes, 2.8 intense hurricanes, and an Accumulated Cyclone Energy (ACE) 103% of average. Their June forecast called 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 slightly above the 50-year average of 10 named storms, 6 hurricanes, and 2 intense hurricanes. TSR predicts a 40% chance of an above-average season, 44% chance of a near-average season, and a 19% chance of a below-average season, as defined by ACE index. TSR rates their skill level as 51% above chance at forecasting the number of named storms, 60% skill for hurricanes, and 44% skill for intense hurricanes. These are far higher skill numbers than the June ones: 26% above chance at forecasting the number of named storms, 15% skill for hurricanes, and 19% skill for intense hurricanes.

TSR projects that 3.8 named storms will hit the U.S., with 1.6 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 August forecasts for U.S. landfalls is 25% above chance. In the Lesser Antilles Islands of the Caribbean, TSR projects 1.1 named storms, 0.5 of these being hurricanes. Climatology is 1.1 named storms and 0.5 hurricanes.

TSR cites one main factor for their increased forecast: higher sea surface temperatures than expected over the tropical Atlantic, due to the fact that the trade winds over the Atlantic should be slower than originally anticipated. Faster than average trade winds 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.

The CSU and TSR groups are done making forecasts for the coming hurricane season, but NOAA is still due to put out an August update.

I'll have an update on Wednesday.
Jeff Masters

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Quoting StormW:


Nice post.

TY and I know he referenced you and I truly do respect your opinion with the sound reasoning you give. There are plenty of days that no 2 mets agree on the weather. That is why I love this career field.
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Quoting HaboobsRsweet:

You are right I did not. Did it ever make it past a yellow circle? I do not think it did. Good comeback

lol now that was funny
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Quoting AllStar17:


No surprise you do not expect development. You never even gave 97L a chance either.

You are right I did not. Did it ever make it past a yellow circle? I do not think it did. Good comeback
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Quoting HaboobsRsweet:
I have been wrong before and maybe I am wrong again but I just see too many negatives at the moment for this storm to survive. Like I said, if I was asked to make a decision today on what is going to happen I would say it is dead. If I was asked 3 days from now maybe I was wrong and the pattern shifted. I just can not convince myself that the pattern will shift and that shear will drop off as much as the models are saying over by the islands. What weather feature is going to reduce the shear so much in the next 5 days?


No surprise you do not expect development. You never even gave 97L a chance either.
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Quoting WeatherStudent:


Sir, all indications are that the season will finally get underway in earnest commencing from next on and beyond. Are you still expecting this to pan out as of tonight, StormW? :)


please translate into English....ty
Member Since: August 13, 2007 Posts: 0 Comments: 10492
I have been wrong before and maybe I am wrong again but I just see too many negatives at the moment for this storm to survive. Like I said, if I was asked to make a decision today on what is going to happen I would say it is dead. If I was asked 3 days from now maybe I was wrong and the pattern shifted. I just can not convince myself that the pattern will shift and that shear will drop off as much as the models are saying over by the islands. What weather feature is going to reduce the shear so much in the next 5 days?
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we didn't get so much as a drop out here on the islands
Member Since: August 13, 2007 Posts: 0 Comments: 10492
hey guys when does D-max start
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Quoting presslord:
Stoopid...You OK? Looked like y'all got pounded pretty hard this evening...


I was in the main building on base when it happened. Yea, it was pretty nasty, one of the stronger storms I'd seen in awhile. Apparently it stormed all weekend here as well, but I was back in Port Orange on special liberty.
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Quoting AllStar17:


Remember Felix???? How quickly it went from a ragged invest to a TS and then to a Cat. 5? This distubance is also only in the early stages of its developmental process. If it is still like this through tomorrow, then I will say it is done, but not yet. StormW also said it still has hope.

Yes I remember many hurricanes from the past and I still think this one is dead. You do not have to get all hot and bothered because someone has a different opinion. You also do not have to reference other people on here to prove your point. I am a very experienced met and have my own mind and can come to my own conclusions. Man last night we had such great discusses bouncing ideas off each other with no one getting so fired up over a different opinion. Can we go back in time?
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Stoopid...You OK? Looked like y'all got pounded pretty hard this evening...
Member Since: August 13, 2007 Posts: 0 Comments: 10492
Quoting wunderkidcayman:

thanks 9n 37w
bookmark that page. If something develops you can get a pretty good idea where it will move to and how far it is from certain places.
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So, is this wave gonna rise out of the ITCZ? Its gonna just run into South America...
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Iz funnny how youcn alwaz tell whose been prinking when they dost....
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Quoting stormwatcherCI:
Go to stormpulse.com

thanks 9n 37w
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Morakot looking like a beast in the making. Gaining size and no doubt building a sizable storm surge. Morakot is very near hurricane strength by the 1 minute mean measure meant right now, and is forecast to reach category 2 equivalent. I'm surprised this hasn't been talked about more in light of our own inactivity.

Link
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1051. Dakster
Welp. Good night everyone. I got a really important test to take tomorrow and I need my sleep.

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1050. Patrap
Theres a big push to overide his veto and ,well..NOAH is around the corner from me here and its the place for young folks and schoolchildren with Mental disabilities recieve,..well used to get care.

Sad stuff to close such a place when he accepted 2 Billion from the Feds fore other stuff.
Typical.
Member Since: July 3, 2005 Posts: 427 Comments: 129439
1049. IKE
Quoting AllStar17:


Still vorticity with our AOI


Near 11N and 30W.

Not where the spin is. Maybe the blob at 11N and 30W with vorticity, will amount to something. Area where the spin is, is on life-support.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
1048. hahaguy
Quoting presslord:
Pat...mental health services should be increased after a disaster...Jindal should be ashamed...


Agreed.
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Quoting wunderkidcayman:

anyone knows
Go to stormpulse.com
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Quoting wunderkidcayman:

anyone knows


It really does not have a "center" It has mid-level turning.
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Pat...mental health services should be increased after a disaster...Jindal should be ashamed...
Member Since: August 13, 2007 Posts: 0 Comments: 10492
1044. Dakster
Orca - WHAT a difference only 83 today, down from 104! It 86 at night here... The pool is 92..
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Quoting IKE:


Still vorticity with our AOI
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Quoting wunderkidcayman:

well guys where is it center

anyone knows
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1041. IKE
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Felicia looking even better in the latest images.
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1039. Dakster
H23 - Thanks... I read it - it would be interesting if we have the same type of season and a nasty winter storm in 2010....

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This whole Felicia/Enrique thing is real cool.
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Quoting StormW:


You've got me beat Orca...only been twice.


Basically the Canadian Navy's third Homeport on the west coast. Victoria, Diego and Hawaii.
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Quoting HaboobsRsweet:

I got to go the other way man and agree with Cyberstorm...yes it changes with the diurnal cycle but if convection does not hold during dmin then there is no hope because during dmax all it does is get back to where it was and never grows or allows a surface low to form. There is weak weak mid level turning. This storm is sick and needs help. Of course we will watch it but if i was asked today will it turn into something I would lean towards no. Shoot it isnt even and invest yet.


Remember Felix???? How quickly it went from a ragged invest to a TS and then to a Cat. 5? This distubance is also only in the early stages of its developmental process. If it is still like this through tomorrow, then I will say it is done, but not yet. StormW also said it still has hope.
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Quoting wunderkidcayman:
guys where is the center of this system

well guys where is it center
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1033. Patrap
Yup press,that would be the distinguished Doofus Gov Jindals decision.

Heck-of-a-Guy,...


Jindal is wrong to veto the funding of NOAH
Member Since: July 3, 2005 Posts: 427 Comments: 129439
Quoting ALCoastGambler:
I agree Storm. Hey everybody Orca sending everyone to Hawaii.......lol


ROFL, I have been there over 30 times... you couldn't pay me to go back.
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Eyewall almost all the way around the eye. That is also a thick eyewall. Intensification could be gradual to rapid after the eye clear out and the eye wall fully surrounds the eye.



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Mental illness tidal wave swamps New Orleans
City's care system shrinking, coming undone
By Audrey Hudson (Contact)

Originally published 04:45 a.m., August 4, 2009, updated 01:15 p.m., August 4, 2009

NEW ORLEANS Washington Times

A mental health crisis that has swamped this city's care facilities as surely as Hurricane Katrina's floodwaters washed over the Lower 9th Ward is about to become even worse, care providers say.

New Orleans already is struggling with fewer than half of the inpatient beds for the mentally ill that it had before the 2005 hurricane - even as suicide rates and the number of people with mental health problems have doubled.

That shortage is about to become even more acute with the scheduled closing Sept. 1 of the New Orleans Adolescent Hospital (NOAH), the city's only public hospital still providing inpatient services for the mentally ill.

The closure, designed to trim $14 million from the state's 2010 budget, will leave New Orleans with 133 beds for mental health inpatient care and will make the city jail - with 60 of those beds - the city's largest psychiatric ward.
Member Since: August 13, 2007 Posts: 0 Comments: 10492
Quoting AllStar17:
CyberStorm

What??????? Disturbances / Invests do suffer from diurnal cycles. Convection wanes during DMIN, and increases during DMAX. And, if a disturbance has a spin, the spin always has a chance to reach the surface. Your comment was absolutely wrong.

I got to go the other way man and agree with Cyberstorm...yes it changes with the diurnal cycle but if convection does not hold during dmin then there is no hope because during dmax all it does is get back to where it was and never grows or allows a surface low to form. There is weak weak mid level turning. This storm is sick and needs help. Of course we will watch it but if i was asked today will it turn into something I would lean towards no. Shoot it isnt even and invest yet.
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Quoting Orcasystems:
Anyone want to go to Hawaii?


Shoot I'll still go! LOL.
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guys where is the center of this system
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Quoting StormW:


Ok! LOL!!
I agree Storm. Hey everybody Orca sending everyone to Hawaii.......lol
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Quoting Orcasystems:
Anyone want to go to Hawaii?

It would still be at least 200 miles S if it continued on that path...plus it would be weakened by low water temps...
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1024. amd
Quoting hurricane23:
My page on the 93 superstorm.


the 1993 superstorm, an amazing winter storm. Pressures fell to 960 mb in Philadelphia, and even though the storm passed less than 40 miles to the southeast (from where I was living at the time), the precipitation from the storm never changed to plain rain.

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CyberStorm

What??????? Disturbances / Invests do suffer from diurnal cycles. Convection wanes during DMIN, and increases during DMAX. And, if a disturbance has a spin, the spin always has a chance to reach the surface. Your comment was absolutely wrong.
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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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