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 BurnedAfterPosting:


That was Wilma, not Mitch

Mitch is tied for 7th with Camille and Dean

Most of the deaths attributed to Mitch was due to massive amounts of flooding in Honduras after the storm made landfall there


He said to that date.
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Quoting Ossqss:


The strongest ATL basin cane to that date, surpassing Gilbert. 888 mb if memory server me right.


That was Wilma, not Mitch

Mitch is tied for 7th with Camille and Dean

Most of the deaths attributed to Mitch was due to massive amounts of flooding in Honduras after the storm made landfall there
Quoting java162:


category 1?????? i think you meant 5!!!!!!


Mitch was at one point a 5, but by the time it had landfalled and stalled over Honduras, it was a Category 1. A similar situation occurred in 2000 with Keith striking Belize, only Keith was a tropical storm at landfall, not a hurricane, and it fortunately did not cause a significant amount of deaths.
Member Since: Posts: Comments:
I had a starbucks once,..walked out the Store and there was another one across the Street,..I thought I sipped myself into a frigging wormhole.


You got Jarhead blood,since you a Black Java Guy,..me too.
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Quoting java162:


category 1?????? i think you meant 5!!!!!!


The strongest ATL basin cane to that date, surpassing Gilbert. 888 mb if memory server me right.

Edit: Nope that's not right, my bad.
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Eye about ready to clear out. RI may occur soon after.

You can definitely still see a spin on theCATL Infrared Satellite Loop, so this disturbance should NOT be written off yet.

Member Since: June 29, 2009 Posts: 13 Comments: 5313
Quoting KoritheMan:


...You do realize Mitch killed upwards of 18,000 people in 1998 in Central America, correct? And it was only a Category 1.


Thank You.
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Quoting KoritheMan:


...You do realize Mitch killed upwards of 18,000 people in 1998 in Central America, correct? And it was only a Category 1.


category 1?????? i think you meant 5!!!!!!
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Pat....I like my coffee cold and black....just like my heart....SJ, on the other hand, likes those sissified high dollar drinks...
Member Since: August 13, 2007 Posts: 0 Comments: 10484
Quoting BurnedAfterPosting:
It really really gets old that poeople think that because someone wants a storm to track that the same person wants death and destruction. It is completely an unfair assumption that is being made there.

I agree with you 100%, that's what I'm trying to explain, even if not that eloquently.
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911 posts about NOTHING, and I made 6
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enacirruh
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Quoting BurnedAfterPosting:
It really really gets old that poeople think that because someone wants a storm to track that the same person wants death and destruction. It is completely an unfair assumption that is being made there.


I'm thinking of typing up a rebuttal to that unsubstantiated notion, and then saving it on Notepad for future use.

copypasta FTMFW. ;)
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Quoting wunderkidcayman:
hi guys I was out so what did I miss update please thanks


Just a heads up,wunder,..always read back and bring oneself up to date as were deeply engrossed in the Atlantic turmoil .
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Quoting Patrap:


Starbucks.?,..give me a second,I wanna picture Paul with a Double Choco-Latte..,LOL


Cough, snicker, gurgle, gonna have to check the shirt that's on its way for coffee stains now. LoL
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Quoting cyclonekid:
Hey I said CARIB. like maybe Central America...


...You do realize Mitch killed upwards of 18,000 people in 1998 in Central America, correct? And it was only a Category 1.
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Quoting presslord:
Chuck...I was @ South Windemere Starbucks about 6P...there was just a little rain...but you could tell it was nasty out that way...


Starbucks.?,..give me a second,I wanna picture Paul with a Double Choco-Latte..,LOL
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Quoting sammywammybamy:
I Have an Idea..

IF THE NHC NEEDS MONEY IT COULD MAKE NAMING RIGHTS TO HURRICANES..

SOME EXAMPLES:

Rush Limbah Hurricane

Drake's Face Lifting Hurricane

Joe's Barber Hurricane


lol lol lol lol lol lol
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It really really gets old that poeople think that because someone wants a storm to track that the same person wants death and destruction. It is completely an unfair assumption that is being made there.
Quoting sammywammybamy:



Here in South Florida... Ive went though Jeanne, Frances , and Wilma...

They were all above or at cat 2 status..

I Dont mind a Tropical Storm hiting me .. but once it hits 74mph... its serious ..and i dont want hurricanes to hit my house..

Wilma Was Pretty scary ... My neighboor's car got hit by a downed tree...

and all my roof tiles were gone..

OUT of Power for 8 Days


Yea,
In Katrina I had 12 Feet of water in my home for 3 and a half weeks, Then Rita caused a portion of my roof to collapse.
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hi guys I was out so what did I miss update please thanks
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The McHurricane
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Quoting sebastianflorida:
Category 5 is the highest category a tropical cyclone can obtain in the Saffir-Simpson scale. These storms cause complete roof failure on many residences and industrial buildings, and some complete building failures with small utility buildings blown over or away. Collapse of many wide span roofs and walls, especially those with no interior supports. Very heavy and irrepairable damage to many wood frame structures and total destruction to mobile/manufactured homes. Only a few types of structures are capable of surviving intact, but only if located at least 3 to 5 miles inland. They include office/condo/apartment buildings and hotels that are of solid concrete construction, public multistory concrete parking garages, and residences that are made of either reinforced brick or concrete/cement block and have hipped roofs with slopes of no less than 35 degrees from horizontal and no overhangs of any kind. The storm's flooding causes major damage to the lower floors of all structures near the shoreline, and many coastal structures can be completely flattened and/or washed away by the storm surge. Storm surge damage can occur up to 4 city blocks inland, with flooding, depending on terrain, reaching 6 to 7 blocks inland. Massive evacuation of residential areas may be required if the hurricane threatens populated areas.[5]

Storms of this intensity can be extremely damaging. Several historical examples include the Labor Day Hurricane of 1935, the 1959 Mexico Hurricane, Hurricane Camille in 1969, Gilbert in 1988, Andrew in 1992, and Dean in 2007.


Surge from Hurricane Katrina penetrated 6 miles inland in some Hancock and Harrison County areas in Mississippi.
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Chuck...I was @ South Windemere Starbucks about 6P...there was just a little rain...but you could tell it was nasty out that way...
Member Since: August 13, 2007 Posts: 0 Comments: 10484
Maybe I dont't want this in my town, I think life would change FOREVER!
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Quoting duajones78413:
Death and destruction is what they cause with landfall. Phenomenon or not, I wish they didnt exist

Fair enough, I understand, trust me if I never hear Hurricane again it will be too soon, but I'm also realistic & know this a seasonal pattern and a part of life as I live basically in Hurricane Alley so I keep posted and on top of all tropical activity during hurricane season, but I also understand those that track them and are absolutely amazed & overwhelmed by their power & destruction. There is 2 sides to almost every story and I try to understand both sides , regardless of right or wrong or the side I personally choose.
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Loop
Member Since: July 11, 2006 Posts: 14 Comments: 11288
From Sat 8th a deep-layered TROF penetrates S&E of Bermuda, weakening the Azores-Bermuda-Florida RIDGE. This weakness may persist throughout next week, and likely pulls to the N or NW into a hostile, high-shear environment any Tropical LO that may approach the E Caribbean
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Nothin' Chuck....but we sure heard it....
Member Since: August 13, 2007 Posts: 0 Comments: 10484
If our AOI has a good night during DMAX, tomorrow everyone will think this will become Ana, just like now during DMIN, it is struggling everyone is writing it off. Some people on this blog just need to be patient.
Member Since: June 29, 2009 Posts: 13 Comments: 5313
Category 5 is the highest category a tropical cyclone can obtain in the Saffir-Simpson scale. These storms cause complete roof failure on many residences and industrial buildings, and some complete building failures with small utility buildings blown over or away. Collapse of many wide span roofs and walls, especially those with no interior supports. Very heavy and irrepairable damage to many wood frame structures and total destruction to mobile/manufactured homes. Only a few types of structures are capable of surviving intact, but only if located at least 3 to 5 miles inland. They include office/condo/apartment buildings and hotels that are of solid concrete construction, public multistory concrete parking garages, and residences that are made of either reinforced brick or concrete/cement block and have hipped roofs with slopes of no less than 35 degrees from horizontal and no overhangs of any kind. The storm's flooding causes major damage to the lower floors of all structures near the shoreline, and many coastal structures can be completely flattened and/or washed away by the storm surge. Storm surge damage can occur up to 4 city blocks inland, with flooding, depending on terrain, reaching 6 to 7 blocks inland. Massive evacuation of residential areas may be required if the hurricane threatens populated areas.[5]

Storms of this intensity can be extremely damaging. Several historical examples include the Labor Day Hurricane of 1935, the 1959 Mexico Hurricane, Hurricane Camille in 1969, Gilbert in 1988, Andrew in 1992, and Dean in 2007.
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Quoting presslord:


C'mon!!!! don'cha see the pinhole eye?!?!?!?!
Gotta love Presslord's sarcasm - Any storm damage out your way from this evening? 1.86 at Charleston Airport
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Quoting SevereHurricane:


People live and have Homes in Central America.



yup
Member Since: August 13, 2007 Posts: 0 Comments: 10484
GFS forecast bust again!
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Quoting presslord:


C'mon!!!! don'cha see the pinhole eye?!?!?!?!


Where is it gonna hit sir?
LOL
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Quoting cyclonekid:
Hey I said CARIB. like maybe Central America...


People live and have Homes in Central America.
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Quoting Drakoen:
LOL?



C'mon!!!! don'cha see the pinhole eye?!?!?!?!
Member Since: August 13, 2007 Posts: 0 Comments: 10484
Quoting SevereHurricane:


You wish? Have you ever been through a Hurricane and then have serious damage done to your home? I can tell ya, its no fun. In 2005 we had to decorate our fema trailer instead of a tree. I don't wish for that kind of stuff.
Hey I said CARIB. like maybe Central America...
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New 'crisis satellites' launched

A rocket has been launched from Kazakhstan carrying two British-built satellites which will help monitor natural disasters.

The UK-DMC2 and Deimos-1 spacecraft will join four platforms already in the sky that together form the Disaster Monitoring Constellation.

The network obtains rapid pictures of areas struck by natural calamities - such as floods, earthquakes and fire.

The imagery is used by governments and aid agencies to co-ordinate relief.
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LOL?

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Death and destruction is what they cause with landfall. Phenomenon or not, I wish they didnt exist
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Quoting cyclonekid:
Wish this thing could go into the CARIB. but shear to HIGH!!


You wish? Have you ever been through a Hurricane and then have serious damage done to your home? I can tell ya, its no fun. In December 2005 we had to decorate our fema trailer instead of a tree. I don't wish for that kind of stuff.
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Quoting duajones78413:
Why would anyone in their right mind wish for a named storm. They can be deadly so why hope for one?

I don't think anyone in their right minds want to see death and destruction from these storms, I know I don't after my experience with Hurricane Ivan in 2004, but in reality they are a phenomenon that is extremely riveting in the way they form, intensify and track, this has become a fascinating thing to watch for weather enthusists. They are just amazed and in awe of their powerful destructful force, but in all honesty and belief , I don't think one person on this blog want to see death & destruction despite the intriguing nature of these beasts.
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Quoting eye:
RIP wave, it is poofing....


I dunno...I'm pretty sure I see a pinhole eye...
Member Since: August 13, 2007 Posts: 0 Comments: 10484
874. eye
RIP wave, it is poofing....
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12N 30.2W seems like we have the sfc L trying to start spining. We may have 98L by tommorow morning.
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Quoting Patrap:
I do have a occasional moment of sanity press,but it usually passes rather fast.



Good! One can have too much of a good thing...but once in a while is OK...
Member Since: August 13, 2007 Posts: 0 Comments: 10484

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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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