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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Quoting StormChaser81:


Probably somewhere on the east coast, most likely Daytona beach to Miami. but probably wont be much to it. word on the streets is FL will get increased pops.

Well, considering that what used to be Fred isn't a TS its kinda hard to predict landfall. It can be anywhere from Key West to Nova Scotia. Or it could not make landfall at all.
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Quoting Bordonaro:

I lived in the Dallas-Ft Worth area of N Central TX for 28yrs!

N Central TX should be the bizarre weather capital of the USA!! N TX has 2 distinct rainfall zones close by!! The DESERT to the W and the Semi-tropics to the SE! We get 36"/yr average!! About 300mi to the W, they get 10", about 200mi to the E they get 50+"

We have gone 84 consecutive days without rain in 1998. Twenty nine days over 100F in a row, 56 for the year!! Was 111F at the DFW airport in 7-98! We went from a severe drought in 2-07, with about 2" for the year, by 7-07, we had 42"!! Seen grapefruit size hail pummel my house and cars in 1993!

Oh, we are at the S end of Tornado Alley!!We had an F2 Tornado go through downtown Ft Worth, TX in 3/00, $500 MIL in damage in 13 min!! The same storm spawned an F4 Tornado in Arlington, TX 15 mi away, 30 min later!! Saw the damage a week after the storm! The house on one side of the street, untouched, across the street 3/4 of the house GONE!!
PLEASE consider yourself fortunate that you live in the Midwest

??? the midwest gets some of the worst tornado outbreaks, too. Look up April 3, 1974 for an example in the extreme direction.
Towns erased.
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Quoting Bordonaro:

I lived in the Dallas-Ft Worth area of N Central TX for 28yrs!

N Central TX should be the bizarre weather capital of the USA!! N TX has 2 distinct rainfall zones close by!! The DESERT to the W and the Semi-tropics to the SE! We get 36"/yr average!! About 300mi to the W, they get 10", about 200mi to the E they get 50+"

We have gone 84 consecutive days without rain in 1998. Twenty nine days over 100F in a row, 56 for the year!! Was 111F at the DFW airport in 7-98! We went from a severe drought in 2-07, with about 2" for the year, by 7-07, we had 42"!! Seen grapefruit size hail pummel my house and cars in 1993!

Oh, we are at the S end of Tornado Alley!!We had an F2 Tornado go through downtown Ft Worth, TX in 3/00, $500 MIL in damage in 13 min!! The same storm spawned an F4 Tornado in Arlington, TX 15 mi away, 30 min later!! Saw the damage a week after the storm! The house on one side of the street, untouched, across the street 3/4 of the house GONE!!
PLEASE consider yourself fortunate that you live in the Midwest


ok, while that is really extreme and bizarre weather, try Indiana sometime haha 70 degress on january 1st this year, and then 70 degrees on july 4th
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Something important to note

HWRF and GFDL all have the center of Ex Fred initialized incorrectly
Quoting atmoaggie:

Gladly, please take it.

Last 7 days:

I lived in the Dallas-Ft Worth area of N Central TX for 28yrs!

N Central TX should be the bizarre weather capital of the USA!! N TX has 2 distinct rainfall zones close by!! The DESERT to the W and the Semi-tropics to the SE! We get 36"/yr average!! About 300mi to the W, they get 10", about 200mi to the E they get 50+"

We have gone 84 consecutive days without rain in 1998. Twenty nine days over 100F in a row, 56 for the year!! Was 111F at the DFW airport in 7-98! We went from a severe drought in 2-07, with about 2" for the year, by 7-07, we had 42"!! Seen grapefruit size hail pummel my house and cars in 1993!

Oh, we are at the S end of Tornado Alley!!We had an F2 Tornado go through downtown Ft Worth, TX in 3/00, $500 MIL in damage in 13 min!! The same storm spawned an F4 Tornado in Arlington, TX 15 mi away, 30 min later!! Saw the damage a week after the storm! The house on one side of the street, untouched, across the street 3/4 of the house GONE!!
PLEASE consider yourself fortunate that you live in the Midwest
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Quoting Weather456:
From Nasa satellite loops - Just dont want to give up.



It should be moving into more favorable conditions by tonight or tomorrow. Shear remains at 20 knots which is why the clouds are getting pulled back.
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Almost:

Link

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Can someone post the link to the models for fred-ex please.Thanks ahead of time.
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Quoting TheCaneWhisperer:



Wouldn't take much to close it though. With shear forecast to relax, tomorrow mornings move to organize may hold.


Looking at Guygee's image loop, it may have been that outflow that stunted the circulation however, it's looking better defined as we head to the evening.
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Quoting kmanislander:


Remember Erika ?. All the models had it making a sharp right turn into the N Atl near 35W and it finished up S of PR in the Caribbean.

Throw those out the window for now IMO


The models also over-intensified Erika by a huge margin.
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Quoting guygee:


the GIMP (for windoze).

Pretty easy, several tuturials on the web...


Thanks
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NHC updated info on disturbance Fred

...INITIAL CONDITIONS...
LATCUR = 25.9N LONCUR = 67.0W DIRCUR = 285DEG SPDCUR = 12KT
LATM12 = 25.1N LONM12 = 64.7W DIRM12 = 280DEG SPDM12 = 12KT
LATM24 = 24.6N LONM24 = 61.8W
WNDCUR = 30KT RMAXWD = 15NM WNDM12 = 25KT
CENPRS = 1011MB OUTPRS = 1015MB OUTRAD = 150NM SDEPTH = S
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

WNDCUR went up 5 kt
CENPRES went down 1 mb
Member Since: September 23, 2005 Posts: 14 Comments: 10872
Quoting TheCaneWhisperer:



Wouldn't take much to close it though. With shear forecast to relax, tomorrow mornings move to organize may hold.


Agreed
anyone think that ULL in the SW Caribbean will make it down to the surface before it hits the mosquito coast
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Quoting JLPR:


Looks like 98L will ditch the old convection and go with the newest one closer to the center
That might speed up its development a little bit.
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Quoting serialteg:


where do you see that?


I see it in StormWs words and 456, both said that the weakness is short-lived

If 98L doesnt start moving WNW soon, it may not go through the weakness completely and could be left behind after the ridge build backs in
Quoting BurnedAfterPosting:


not closed



Wouldn't take much to close it though. With shear forecast to relax, tomorrow mornings move to organize may hold.
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Quoting cchsweatherman:


Used the wrong word. Should have stated building, not deepening.
I thought you found a new type of weather phenomenon...:)
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Quoting BurnedAfterPosting:


high pressure builds in


where do you see that?
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Quoting serialteg:


why will the weakness be short lived?


high pressure builds in
Quoting futuremet:


Guygee, which freeware did you use to do this GIF loop?


the GIMP (for windoze).

Pretty easy, several tuturials on the web...
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Quoting BurnedAfterPosting:


??? what are you talking about?

The weakness will be short lived, even StormW said he wasnt buying it at this time. All the models that curve 98L north also have it going WNW right now and its not.

Lastly how many times have we seen the model consensus be dead wrong early on?


why will the weakness be short lived?
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From Nasa satellite loops - Just dont want to give up.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting serialteg:


as in, why the westcasting


??? what are you talking about?

The weakness will be short lived, even StormW said he wasnt buying it at this time. All the models that curve 98L north also have it going WNW right now and its not.

Lastly how many times have we seen the model consensus be dead wrong early on?
Repost just for guygee, cause I know he would like it:

Now that is an ERC!
Link
Very cool.
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Quoting hydrus:
Deepening high pressure??


Used the wrong word. Should have stated building, not deepening.
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Quoting serialteg:
hey guys can you fill me in with your west-tracking info on the invest?


as in, why the westcasting
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565. JLPR


Looks like 98L will ditch the old convection and go with the newest one closer to the center
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Quoting guygee:

-546,-5477, -548,...
LOL
Seriously, any system with a llc and nearby deep convection approaching the Bahamas bears watching this time of year.

OTOH, interesting how when the southern convection collapsed this morning it sent an outflow boundary washing north over the llc.

XFred

(Apologies to low-bandwith users)

Hey guygee. Been a while. How ya are?
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Quoting TheCaneWhisperer:


not closed
Atmospheric dynamics aside, FredEx's OHC going to get better. Not terrific, but better.



Caveat: One of the satellites used for SSH measurements (Jason-1) went into safe mode a couple of days ago and, as far as I know, hasn't come back yet. Probably will not have much of an effect on OHC values this time of year...yet.
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Quoting obsessedwweather:
Can someone tell/show me where "Fred's" possibilities of landfall are please???


Probably somewhere on the east coast, most likely Daytona beach to Miami. but probably wont be much to it. word on the streets is FL will get increased pops.
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Quoting OSUWXGUY:


Yeah. I can agree with a western BAM solution, I just don't see the southwest jog until much later (near the Bahamas) if at all. The ridging remains flat/weak with the trough over New England at the moment.

The GFDL has the center at 25N 70W at 12UTC tomorrow. It's already around 26N 68 West.

So to be on track it would have to slow WAY down and move WSW...

Low Level Steering Loop


Hehe... definitely an agreement...
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Quoting guygee:

-546,-5477, -548,...
LOL
Seriously, any system with a llc and nearby deep convection approaching the Bahamas bears watching this time of year.

OTOH, interesting how when the southern convection collapsed this morning it sent an outflow boundary washing north over the llc.

XFred

(Apologies to low-bandwith users)


Guygee, which freeware did you use to do this GIF loop?
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Quoting cchsweatherman:
For right now, I will be going with the current TVCN track for ex-Fred since I do believe it will eventually get pushed towards the WSW by deepening high pressure to the north, but not as extreme as the GFDL and HWRF models show. Given the current state of the system and computer model intensity forecasts, it would not be surprising to see regeneration, but I'm not sold yet on whether that will happen or not.
Deepening high pressure??
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Can someone tell/show me where "Fred's" possibilities of landfall are please???
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Quoting guygee:

-546,-5477, -548,...
LOL
Seriously, any system with a llc and nearby deep convection approaching the Bahamas bears watching this time of year.

OTOH, interesting how when the southern convection collapsed this morning it sent an outflow boundary washing north over the llc.

XFred

(Apologies to low-bandwith users)


you can totally see the NE shear, thanks
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553. LBAR
Definite swirl off of the South Carolina coast...about 75W35N...not sure if it's a surface low, though?
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hey guys can you fill me in with your west-tracking info on the invest?
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551. JLPR
Quoting serialteg:


www.askjesus.com/tropical


xD
Member Since: September 4, 2007 Posts: 36 Comments: 5223
For right now, I will be going with the current TVCN track for ex-Fred since I do believe it will eventually get pushed towards the WSW by building high pressure to the north, but not as extreme as the GFDL and HWRF models show. Given the current state of the system and computer model intensity forecasts, it would not be surprising to see regeneration, but I'm not sold yet on whether that will happen or not.

EDITED: Changed "deepening high pressure" to "building high pressure".
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Quoting IKE:

Waiting for the....
...

And waiting for the....

"Don't write Fred off just yet" comments....

In 3....2.....1.....

-546,-5477, -548,...
LOL
Seriously, any system with a llc and nearby deep convection approaching the Bahamas bears watching this time of year.

OTOH, interesting how when the southern convection collapsed this morning it sent an outflow boundary washing north over the llc.

XFred

(Apologies to low-bandwith users)
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POST UPDATED:
South Florida StormWatch
(main site)
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Quoting JLPR:
I got it, I understand 98L
we got several swirls rotating around a broad area of low pressure =]

and I actually see the center of the broad low at 12.5N 40W
the thing is where will the center consolidate finally?


www.askjesus.com/tropical
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Navy model very aggressive with new invest and forecasting the north turn

Steering forecast here also going for an obliteration of the current ridge
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Quoting Weather456:


well the weakness for 98L is more pronounce than with Erika.


However, it is not expected to last long.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting BurnedAfterPosting:


way off again, center of Ex Fred is at 25.9N

not sure who is posting over there, but they are way off on both accounts


Don't know it a website someone tryng to sell their hurricane tracker software.

Link to Stormpulse

Glad to know this, someone told me this program was excellent...thanks for the info.
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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.