Disturbance 98L probably no threat to land

By: Dr. Jeff Masters , 1:46 PM GMT on September 18, 2009

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A tropical disturbance (98L), is located midway between Africa and the Lesser Antilles Islands. This disturbance has a well-defined surface circulation, and has developed a modest amount of heavy thunderstorm activity overnight. This morning's QuikSCAT pass (Figure 1) shows a complete, circular wind pattern around the low pressure center of 98L, but top winds were only 25 mph. Wind shear is moderate, about 15 knots, and Sea Surface Temperatures are 28°C, which is about 2°C above the 26°C threshold needed to support a tropical cyclone. There is a large amount of dry air to the north and west of 98L, and this dry air is interfering with development.

The global computer models predict differing amounts of wind shear in the path of 98L as it moves west-northwest at 10 mph over the next three days. The ECMWF, GFS, and UKMET models do not develop 98L, while the NOGAPS, GFDL, and HWRF do. The models that do develop 98L predict that a strong trough of low pressure will turn 98L to the northwest and then north beginning on Monday, with the result that 98L misses the Lesser Antilles Islands by at least 500 miles. Given the moderate or higher wind shear in 98L's path, and dry air to the northwest, the system should develop only slowly. NHC is giving 98L a medium (30 - 50%) chance of developing into a tropical depression by Sunday. At this time, it does not appear that 98L will ever threaten any land areas.

The remains of Hurricane Fred are still spinning away, near 25N 66W, about 900 miles east of Florida. Wind shear is 20 knots, which is marginal for development, and there is very dry air surrounding ex-Fred on all sides. None of the computer models develop ex-Fred, and it will have a tough time regenerating with so much dry air and wind shear. The remains of Fred should move over Florida Monday night or Tuesday morning.


Figure 1. Morning QuickSCAT image of the Atlantic, showing the well-defined surface circulation of disturbance 98L. Image credit: NOAA/NESDIS.

One year anniversary of Hurricane Ike
I've been focusing this week on the 20th anniversary of Hurricane Hugo, but we also passed the one year anniversary of Hurricane Ike. Many areas along the Texas and Louisiana coast affected by Ike have fully recovered, but recovery efforts will still take many more years in other areas. In Galveston, which suffered $3.2 billion in damage, 75% of the businesses have reopened, and 95% of the population has returned. Boston.com has posted a very nice series of clickable images that show before and after scenes of some of the areas that have recovered from Hurricane Ike.

Ike washed away huge sections of beach and dunes that helped protect the Texas coast from more serious damage, and this week the state legislature approved $135 million in funds to help replace these critical natural protection systems. The restored beaches will probably last ten years, barring another strike by a hurricane of Ike's stature. Texas considers two-thirds of its 367-mile shoreline to be critically eroding, which it defines as a historical rate of more than 2 feet a year. Much of this erosion can be blamed on sea level rise. Global sea level rose seven inches over the past century, and is expected to rise at least that much over the coming century.


Figure 2. Villagers in Haiti plant one of their "Million Tree Campaign" trees. Image credit: Lambi Fund of Haiti.

Hurricane relief donations
There hasn't been a need for new hurricane-related disaster relief efforts this year, in stark contrast to 2008. However, the charities we rely on to provide disaster relief still require funds to operate in quiet years, and I encourage you to consider a donation at this time to one of my two favorite disaster relief charities. Portlight.org, which was very effective at helping out isolated, under-served communities in the wake of Hurricane Ike, is committed to raising $12,000 to purchase and outfit a mobile kitchen. This kitchen will be capable of feeding up to 2,000 people two hot meals per day in post-disaster situations. The Lambi Fund of Haiti has launched its "Million Tree Campaign", which aims to use local labor to plant a million trees over the next three years along severely deforested slopes in Haiti. Both of these charities wrote to me several times last year about the stunning generosity readers of this blog showed with their donations. Thanks!

Twenty years ago today
As Hurricane Hugo approached the U.S. Virgin Islands in the early morning hours of September 18, 1989, the storm slowed down to 10 mph. The slower speed allowed Hugo to punish the island of St. Croix with the worst beating of any location along the hurricane's destructive path. At 2am local time on September 18, 1989, Hurricane Hugo's eyewall struck St. Croix, bringing incredibly ferocious Category 4 winds, sustained at 140 mph. The hurricane's gusts were remarkably violent, and many residents witnessed tornado-like vorticies barreling across the island as the hurricane raged about them. A storm surge of 2 - 3 feet, topped by battering waves 20 - 23 feet high, assaulted the coast, adding to the destruction. Wunderground member Mike Steers wrote me to describe his experience on St. Croix: "Hugo was incredible. Many vortexes came in that night. The roar and intensity of the winds that night were incredible. When the eyewall came over, we were forced to take refuge in the bathroom as the rest of the house came apart. The pressure was so low outside the house that all of the water was sucked out of the toilet and an air draft was created through the toilet. Just when I thought it was as bad as it would get, the intensity of it all dialed up even higher. Dozens and dozens of times, my ears would violently pop due to rapid pressure changes. The next morning, of course, the devastation was unbelievable. In my front yard was a 18-foot boat with an outboard on it, that had been picked up from a marina two miles away. I had lost my house, and job, the Seaplane company I was a pilot for. After a couple months, I had to leave everything behind. In some respects, after 20 years, there an many aspects of the society that have yet to recover". Two people were killed on St. Croix, 80 injured, and 90% of the buildings were damaged or destroyed. Damage estimates for St. Croix were astronomical, over $1 billion, and the island's entire infrastructure was virtually wiped out. Six weeks after the hurricane, only 25% of the public roads had been cleared, and only 25% of the island had power.


Figure 3. GOES visible satellite image of Hurricane Hugo taken on September 18, 1989. Note the lack of cloud cover on the hurricane's southwest side, indicating that strong upper-level winds from the southwest were likely creating wind shear, weakening the storm. Image credit: Google Earth rendition of the NOAA HURSAT data base.

As Hugo departed St. Croix, strong upper-level winds from the southwest created wind shear that weakened the storm to a Category 3 hurricane with 130 mph winds. The upper level winds also caused Hugo to accelerate to 15 mph and turn more northwest. The eye passed over Puerto Rico's Vieques Island at 8am and over Fajardo on the extreme northeastern tip of Puerto Rico at 9am. On Culebra Island, an island twelve miles east of Fajardo, a gust to 170 mph was recorded by the ship Night Cap in the main harbor. The south-facing harbor received sustained southerly winds in excess of 120 mph for several hours as Hugo roared by to the south. The resulting wave "set-up" created a storm surge in excess of 13 feet in the supposedly hurricane-proof harbor. A large portion of the Caribbean's charter boat fleet, some 200 boats, was sheltering in Culebra's harbor, and 136 of these boats were badly damaged or sunk. Over 80% of the wooden structures on both Culebra and Vieques were destroyed.


Figure 4. Damage on St. Croix (two top photos), Culebra Island (bottom right), and Puerto Rico's Roosevelt Roads Navy Base (bottom left), after Hurricane Hugo. Image credit: NOAA Photo Library.

Along the northeastern coast of Puerto Rico, waves up to ten feet high riding on top of a 3 - 4 foot storm surge caused severe coastal flooding of low-lying areas. Hugo's winds tore into Puerto Rico's El Yunque rainforest, downing thousands of trees. The agricultural sector was devastated, with nearly all of the island's banana and coffee crops wiped out. Twelve deaths in Puerto Rico were attributed to Hugo, six of which occurred in the southern city of Guayama where some residents were electrocuted by downed power lines. Nearly 28,000 people were left homeless by the storm, and damage to the island exceeded $1 billion.

Storm chaser Michael Laca was at Luquillo Beach on the northeast shore of Puerto Rico, and has posted a remarkable 28-minute video on YouTube of Hurricane Hugo footage.

Jeff Masters

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Fred is being sheared by 20 knots of shear between a ridge over the Bahamas and the upper low that was over Fred (now to its southeast)

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NHC ran 18Z SHIPS using OFCI track, so they have done a track on 07L.

AL 07 2009091812 03 OFCL 0 253N 660W 25
AL 07 2009091812 03 OFCL 12 256N 680W 25
AL 07 2009091812 03 OFCL 24 259N 700W 25
AL 07 2009091812 03 OFCL 36 262N 715W 25
AL 07 2009091812 03 OFCL 48 266N 731W 25
AL 07 2009091812 03 OFCL 72 272N 760W 25
AL 07 2009091812 03 OFCL 96 280N 790W 25
AL 07 2009091812 03 OFCL 120 290N 825W 25
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Quoting nrtiwlnvragn:
18Z came out early so they may change the data. Down 1 mb

AL 07 2009091818 BEST 0 259N 670W 25 1012 LO


...INITIAL CONDITIONS...
LATCUR = 25.9N LONCUR = 67.0W DIRCUR = 287DEG SPDCUR = 12KT
LATM12 = 25.1N LONM12 = 64.7W DIRM12 = 280DEG SPDM12 = 12KT
LATM24 = 24.6N LONM24 = 61.8W
WNDCUR = 25KT RMAXWD = 15NM WNDM12 = 25KT
CENPRS = 1012MB OUTPRS = 1015MB OUTRAD = 150NM SDEPTH = S
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM


To add to your post:

000
WHXX01 KWBC 181756
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1756 UTC FRI SEP 18 2009

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE FRED (AL072009) 20090918 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090918 1800 090919 0600 090919 1800 090920 0600

LAT LON LAT LON LAT LON LAT LON
BAMS 25.9N 67.0W 26.5N 68.8W 27.0N 70.3W 27.1N 72.0W
BAMD 25.9N 67.0W 26.0N 68.6W 26.0N 69.8W 26.0N 70.8W
BAMM 25.9N 67.0W 26.3N 68.7W 26.5N 70.0W 26.5N 71.4W
LBAR 25.9N 67.0W 26.4N 68.6W 26.9N 69.8W 27.3N 70.9W
SHIP 25KTS 28KTS 33KTS 38KTS
DSHP 25KTS 28KTS 33KTS 38KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090920 1800 090921 1800 090922 1800 090923 1800

LAT LON LAT LON LAT LON LAT LON
BAMS 27.4N 74.1W 28.2N 78.0W 29.4N 81.7W 30.8N 85.3W
BAMD 26.0N 71.8W 26.3N 73.8W 26.6N 76.4W 26.4N 79.5W
BAMM 26.6N 72.9W 27.1N 76.0W 27.7N 79.4W 28.6N 82.9W
LBAR 27.3N 72.1W 27.2N 74.1W 27.4N 76.4W 27.5N 79.7W
SHIP 43KTS 49KTS 53KTS 55KTS
DSHP 43KTS 49KTS 53KTS 33KTS
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Quoting TriniGirl26:


Awwwww...missed you too... take a wild guess (Wink)


St. Augustine????
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LOVE THIS WEATHER!

Lafayette, Purdue University Airport
Lat: 40.43 Lon: -86.93 Elev: 623
Last Update on Sep 18, 1:54 pm EDT

Fair

78 °F
(26 °C)
Humidity: 21 %
Wind Speed: NE 10 MPH
Barometer: 30.16" (1021.0 mb)
Dewpoint: 35 °F (2 °C)
Heat Index: 78 °F (26 °C)
Visibility: 10.00 mi.
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Quoting Seasidecove:


LOL!!! and no sooner than it starts to clear up for you, it starts to sprinkle here!! ...go figure!


yup thats about right.
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Good afternoon SW, you got mail.

I am good but you are better.

Meanwhile, 98L has lost most of the thunderstorms that were there this morning. However, a new area of thunderstorms developed on the northwest side of the circulation probably a hint of an increasingly conducive environment. From satellite animations it appears is moving a bit north of due west.

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Quoting alaina1085:


Exactly lol. And now the sun is shining again... gotta love our weather.


LOL!!! and no sooner than it starts to clear up for you, it starts to sprinkle here!! ...go figure!
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Quoting weatherbro:
according to long ranch models, the jet stream will take a big dip(for late September) over the east(5-9 days from now). Although a week later then originally forecasted, an early dry season is expected for Florida! Woopie!!!


Are those long ranch models calibrated in Hidden Valley? lol
according to long ranch models, the jet stream will take a big dip(for late September) over the east(5-9 days from now). Although a week later then originally forecasted, an early dry season is expected for Florida! Woopie!!!
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Quoting TriniGirl26:
shouldn't shear be taking 98L apart about now?


maybe, but I think slow development is possible?
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shouldn't shear be taking 98L apart about now?
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Quoting Seasidecove:


Our typical Summer time pattern ...LOL! Popcorn Thunder showers! Gotta love'em!


Exactly lol. And now the sun is shining again... gotta love our weather.
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18Z came out early so they may change the data. Down 1 mb

AL 07 2009091818 BEST 0 259N 670W 25 1012 LO


...INITIAL CONDITIONS...
LATCUR = 25.9N LONCUR = 67.0W DIRCUR = 287DEG SPDCUR = 12KT
LATM12 = 25.1N LONM12 = 64.7W DIRM12 = 280DEG SPDM12 = 12KT
LATM24 = 24.6N LONM24 = 61.8W
WNDCUR = 25KT RMAXWD = 15NM WNDM12 = 25KT
CENPRS = 1012MB OUTPRS = 1015MB OUTRAD = 150NM SDEPTH = S
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM
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Quoting PcolaDan:



Well said!



Cardinal Fang, bring forth the comfy chair!
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4 day trip from it's current position to the coast via the GFDL. That's a slow mover for sure.
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Quoting IKE:


Latest NOGAPS takes a decreasing vorticity across that exact area and then loses it.


Hehe... indeed.
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Quoting alaina1085:


Seem to be but there just spotty showers so it could dissipate.


Our typical Summer time pattern ...LOL! Popcorn Thunder showers! Gotta love'em!
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Very true, when you've been through the real storms that life has to dish out the weather becomes quite mundane. As long as it doesn't blow down your house - LOL!!
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Quoting Grothar:


Hey Trini, Where have you been? We've missed you. You do not have to answer!


Awwwww...missed you too... take a wild guess (Wink)
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Interesting Windsat, also.

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Quoting Seasidecove:


Partly Cloudy and humid! here in BSL, MS. Is it headed this way?


Seem to be but there just spotty showers so it could dissipate.
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469. IKE
Quoting WxLogic:
Who knows... it might go over Lake O. and do a Fay.


Latest NOGAPS takes a decreasing vorticity across that exact area and then loses it.
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Quoting nrtiwlnvragn:


That is the 12Z run. NHC does not post invest information on their HTML webpages.


Thanks, couldn't read the hours, too small. And yes divdog, I am aware it is a "swirl". My mother's family has lived in Florida since 1923 so I am not unfamiliar with storms. Just prefacing.
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Quoting TriniGirl26:


lol...hey matt...yeah i know, i missing these days...can't help it..still in work here i have about a hour again then i can say i seeing my house. so whats the lastest around here?


latest, well besides a couple of spanish inquisitions.... haha well fredEx is looking to try to redevelop, and we now have 98L
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Quoting Seasidecove:


Partly Cloudy and humid! here in BSL, MS. Is it headed this way?
is what headed where
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Who knows... it might go over Lake O. and do a Fay.
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463. IKE
Quoting InTheCone:


I have noticed that you have a thick hide, what with all the flamethrowers aimed at you lately you'd be blackened beyond recognition by now if you didn't!


It's just the weather...no big deal. Nothing you can do about it anyway.
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Quoting tornadodude:


hey stranger!!


lol...hey matt...yeah i know, i missing these days...can't help it..still in work here i have about a hour again then i can say i seeing my house. so whats the lastest around here?
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Quoting alaina1085:
Afternoon everyone,

its raining AGAIN here in SE LA.


Partly Cloudy and humid! here in BSL, MS. Is it headed this way?
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Quoting IKE:


If I'm wrong about something, I have no problem coming on here and admitting it. I don't do this for a living...forecasting, and it doesn't bother me in the least to be wrong.


I have noticed that you have a thick hide, what with all the flamethrowers aimed at you lately you'd be blackened beyond recognition by now if you didn't!
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Quoting TriniGirl26:
Good Afternoon Everyone...whats new and what have i missed the last 2 days?


Models being run on Fred again with possibility of re-gen from the NHC.

98L East Atl, Slowly getting better organized.
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Quoting Grothar:


Hey, I don't like that model. The GFDL takes it two blocks south of our home. Why isn't the NHC posting a model? This is the 18Z correct?


That is the 12Z run. NHC does not post invest information on their HTML webpages.
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Quoting Grothar:


Hey, I don't like that model. The GFDL takes it two blocks south of our home. Why isn't the NHC posting a model? This is the 18Z correct?
because its a naked swirl
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Quoting TriniGirl26:
Good Afternoon Everyone...whats new and what have i missed the last 2 days?


Hey Trini, Where have you been? We've missed you. You do not have to answer!
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455. IKE
Quoting InTheCone:


At least your honest! Personally, I have tended to agree with you on this one all along, with just a hint of "what if Tampa's right??" LOL!!


If I'm wrong about something, I have no problem coming on here and admitting it. I don't do this for a living...forecasting, and it doesn't bother me in the least to be wrong.
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Watch closely as the remnants of Fred slides up and under a moister and calmer upper level wind environment. It's like watching crystallization under a microscope. Something which, if you've never done it, I recommend.


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If you zoom in on visable of exfred, almost moving NW, call it N of WNW.
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TPC/TAFB 72 hour surface forecast. Shows trof in the area of the North Bahamas.

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Quoting IKE:


(1)Crow taken out of freezer....check.
(2)Getting A1 Sauce at Wal-Mart this afternoon...check.


At least your honest! Personally, I have tended to agree with you on this one all along, with just a hint of "what if Tampa's right??" LOL!!
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Quoting nrtiwlnvragn:


Hey, I don't like that model. The GFDL takes it two blocks south of our home. Why isn't the NHC posting a model? This is the 18Z correct?
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Quoting TriniGirl26:
Good Afternoon Everyone...whats new and what have i missed the last 2 days?


hey stranger!!
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Quoting StormW:


Afternoon, ma'am!


Howdy Chief!
Looks like a wet week for you.
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Quoting IKE:
After everything I've said about drop-dead Fred, watch it make it into the soup-bath known as the GOM.


Getting prepared then.

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Good Afternoon Everyone...whats new and what have i missed the last 2 days?
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Quoting BurnedAfterPosting:


you should be a motivational speaker lol


I just believe people should be treated with respect; including their opinions and judgements. I do not believe anyone would be on this blog unless they held a particular interest in the weather. They best way one learns is to listen to what others have to say. We may disagree, but attacking another's opinion is simply not civil. Very simple.
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443. IKE
After everything I've said about drop-dead Fred, watch it make it into the soup-bath known as the GOM.
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Quoting Grothar:


No matter how may prefaces one uses, statements are always open to misunderstanding. Ever been on a debate team? I think it is why so many people are reluctant to make a statement, for fear of ridicule and misjudgment. Just keep blogging!! You're doing OK.



Well said!

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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.