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 jeffs713:

The Marina district in the 1989 San Francisco quake is a prime example of what liquefaction does in a quake. And that was a 7.0. A 7.8 is roughly 15-20 times more powerful (in terms of energy released).


That is 100% true, but liquifaction usually occurs in smaller areas. The fear is that when a moderate earthquake goes through hard bedrock, the tremors are felt for much longer distances and can cause greater damage. Too much to put in here, but look up the scenarios on a quake in Boston or New York and it shall give you an idea of the rationale. It truly is interesting.
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Quoting Tazmanian:
hows zombie fred this PM
he's using a walker kinda shuffeling around
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Quoting Grothar:


Knew I liked you for a reason, Flood. Recognize any familiar names in your research? Everything you say is quite true. However, later studies expounded on the data collected in the 1990's which makes the scenario even worse, due to the finding of extensive faults through harder rock. Would be a big shake for a large part of the country were it ever to occur.


Everyone wants to talk about the San Andreas and yes, when it goes with a "big one" it's pretty devestatiing, but the New Madrid fault zone and the surrounding deep faults are over 3 miles down, causing far reaching vibration...cities across the midwest will see damage but STL and Memphis will see the worst of it
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Hey the New Orleans NWS, says that another low pressure cell will be moving out of the Plain States to reinforce the current Low over the Lower MS Valley, Keeping us in the Washing Machine for the next 5 days...will this have any effect on Fred, as to it's eventual track..or no?
Member Since: June 21, 2009 Posts: 0 Comments: 78
Quoting JLPR:


broad area of low pressure, so multiple swirls are possible
it will be like that until one finally establishes as the dominant one
Thanks, for your answer, lets see what happens.
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Quoting rwdobson:


This shear is very evident on satellite images. I think people would do well to spend more time looking at the images and less time looking at shear maps...

Very true. Satellite will also show mid-level or narrow-layer shear very well.
Member Since: August 3, 2008 Posts: 16 Comments: 5886
"that was a 7.0. A 7.8 is roughly 15-20 times more powerful (in terms of energy released)."

i thought it was a log scale where 8 would be ten times are powerful as 7...
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Quoting homelesswanderer:


Afternoon Everyone! I read a book about this scenario called 8.0. It gave a fictitious account of the events that could unfold if a quake of that magnitude struck the New Madrid fault. Chilling to say the least. When I read it I thought some of it was too far out there to be true. After 2005 I don't think that anymore. Good read though. :)


May I ask the name of the book? Thanks
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Quoting watcher123:
704:

Yes, that region is severely vulnerable to liquifaction, sand plumes, and river course changes in 7.8+ earthquakes. We're talking like Tower of Pisa for everything in the affected area.

Some of the damage in the 1811-12 events was probably caused by Raleigh waves, as I've seen a program on television about it and they had barns and houses which literally rolled over on the surface of the ground. Only a Raleigh wave can do this.

If a quake that bad hits in modern times it would do incredible damage.


The February 7th 1812 earthquake rang churchbells in Boston over 1300 miles away
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Quoting Floodman:


The places NOT to be if the fault goes with a strong temblor is Memphis or St Louis...their downtowns are built on alluvial flood deposits and that ground will liquefy during a strong event...imagine the Met Center in downtown St Louis swaying say 15-20 feet.

A study done in the late 80s/early 90s said that most of the highway overpasses and bridges as well as flyovers will be down and some 70% of St Louis' downtown will be destroyed given a 7.8; the 1811-12 events were 8-8.2


Knew I liked you for a reason, Flood. Recognize any familiar names in your research? Everything you say is quite true. However, later studies expounded on the data collected in the 1990's which makes the scenario even worse, due to the finding of extensive faults through harder rock. Would be a big shake for a large part of the country were it ever to occur.
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Quoting Floodman:


The places NOT to be if the fault goes with a strong temblor is Memphis or St Louis...their downtowns are built on alluvial flood deposits and that ground will liquefy during a strong event...imagine the Met Center in downtown St Louis swaying say 15-20 feet.

A study done in the late 80s/early 90s said that most of the highway overpasses and bridges as well as flyovers will be down and some 70% of St Louis' downtown will be destroyed given a 7.8; the 1811-12 events were 8-8.2

The Marina district in the 1989 San Francisco quake is a prime example of what liquefaction does in a quake. And that was a 7.0. A 7.8 is roughly 15-20 times more powerful (in terms of energy released).
Member Since: August 3, 2008 Posts: 16 Comments: 5886
So initially I thought that the circulation associated with Fred was getting compressed/squished from the west...

On closer evaluation, you can watch the dry air eroding the deeper precipatable water on the western side of Fred...pretty dramatic stuff...

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hows zombie fred this PM
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Quoting Floodman:


The places NOT to be if the fault goes with a strong temblor is Memphis or St Louis...their downtowns are built on alluvial flood deposits and that ground will liquefy during a strong event...imagine the Met Center in downtown St Louis swaying say 15-20 feet.

A study done in the late 80s/early 90s said that most of the highway overpasses and bridges as well as flyovers will be down and some 70% of St Louis' downtown will be destroyed given a 7.8; the 1811-12 events were 8-8.2


Afternoon Everyone! I read a book about this scenario called 8.0. It gave a fictitious account of the events that could unfold if a quake of that magnitude struck the New Madrid fault. Chilling to say the least. When I read it I thought some of it was too far out there to be true. After 2005 I don't think that anymore. Good read though. :)
Member Since: August 15, 2008 Posts: 10 Comments: 3665
Quoting ncstorm:
Im seeing that a lot of people are saying exFred will be going into Florida but I can remember earlier this week that Dr.Masters say it would go in SC/NC..what has changed since then?


Ridge is building in, no trof
725. JLPR
Quoting jurakantaino:
There seems to be two COC one at 34W 13.5N, and another one at 33W-13.5N, any thoughts?


broad area of low pressure, so multiple swirls are possible
it will be like that until one finally establishes as the dominant one
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Im seeing that a lot of people are saying exFred will be going into Florida but I can remember earlier this week that Dr.Masters say it would go in SC/NC..what has changed since then?
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On Freddy, XFred, 07 etc...

I'll stick with the old addage of Yogi Berra...."It ain't over till it's over!"

Especially when it comes to this years storms!
Member Since: June 21, 2009 Posts: 0 Comments: 78
There seems to be two COC one at 34W 13.5N, and another one at 33W-13.5N, any thoughts?Link
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all this bickering is pretty pointless

Ex Fred is being sheared; TRUE

Ex Fred will be moving into a more favorable environment tomorrow; TRUE

Ex Fred will likely make "landfall" somewhere in Florida in 3 to 4 days; TRUE


That is pretty much it for now, not sure what all the childish bickering is about
Quoting Fshhead:
My amateur eyes tell me a weak TS at best before land ho!!!


I agree
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Quoting jeffs713:

LOL. Gulden's spicy brown mustard is what I would go for, IMO.


a little mustard with a side of crow, WU special :)
Member Since: June 28, 2006 Posts: 25 Comments: 8360
My amateur eyes tell me a weak TS at best before land ho!!!
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Quoting BDAwx:
just on a note of interest choi-wan seems to be exhibiting a double concentric eye-wall feature... pretty cool huh?


cool, can you give us a link or an image please? thank ya
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting Floodman:


What's the latest QScat show? If it looks like this morning's image, you'll need some mustard

LOL. Gulden's spicy brown mustard is what I would go for, IMO.
Member Since: August 3, 2008 Posts: 16 Comments: 5886
713. BDAwx
just on a note of interest choi-wan seems to be exhibiting a double concentric eye-wall feature... pretty cool huh?
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"NHC says favorable"

NHC says "could become more favorable"...and they also say less than 30% chance of redevelopment.
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Quoting Drakoen:
07L is suffering from northerly shear which is resulting in diminishing convection being pushed to the south. Upper level winds, however, will be conducive for development tomorrow.


Fred is suffering?? What about us! We are suffering from overfrederization. This is more than "Nightmare on Elm Street".
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Quoting Fshhead:



THANX!! That was my point, never said it was not heading into more favorable conditions. lol


Then you're absolutely correct! :)
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709. srada
Quoting btwntx08:

and u are too # 45


that was harsh..to say SOMEONE is dead too? he/she was talking about a STORM for goodness sake..what is wrong with you???
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Quoting Drakoen:
07L is suffering from northerly shear which is resulting in diminishing convection being pushed to the south. Upper level winds, however, will be conducive for development tomorrow.



THANX!! That was my point, never said it was not heading into more favorable conditions. lol
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Quoting Drakoen:
07L is suffering from northerly shear which is resulting in diminishing convection being pushed to the south. Upper level winds, however, will be conducive for development tomorrow.


This shear is very evident on satellite images. I think people would do well to spend more time looking at the images and less time looking at shear maps...
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Quoting rwdobson:


Ok, well, that guidance has been wrong, dead wrong, quite few times this season. so i'm not sure why you'd put much stock in it.

what you could do is look at the indivdual layers of the atmosphere in the model runs...look closely at various sat images to see evidence of shear...look at soundings from nearby areas...it's more work than simply looking at a 1-parameter map, but likely to be more accurate.


Then I would be wanting an actual paycheck. I understand all that but, while at work, that's a tall order. NHC says favorable and so does the GFS, works for me right now.

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Quoting Stormchaser2007:




I meant the verge of 20 knots where 07L is at.. shear has increased to 30 knots to the east of it.
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Quoting Grothar:


And you are still there? Have you read the latest on the activity lately? It is becoming active again. And you live in tornado country as well. I heard Finland is nice. Are you near New Madrid? and I know it is pronounced Ma'drid not Madrid'.


The places NOT to be if the fault goes with a strong temblor is Memphis or St Louis...their downtowns are built on alluvial flood deposits and that ground will liquefy during a strong event...imagine the Met Center in downtown St Louis swaying say 15-20 feet.

A study done in the late 80s/early 90s said that most of the highway overpasses and bridges as well as flyovers will be down and some 70% of St Louis' downtown will be destroyed given a 7.8; the 1811-12 events were 8-8.2
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07L is suffering from northerly shear which is resulting in diminishing convection being pushed to the south. Upper level winds, however, will be conducive for development tomorrow.
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Quoting reedzone:
That new shear map shows wind shear on the verge of 20 knots, 07L is already moving into the favorable shear.


Member Since: June 9, 2007 Posts: 4 Comments: 15921
Quoting hydrus:
He is alive, he is dead, he is open, he is closed......yyyaaaawwwwnnn!



Fred is: Schizofredic

LOL too funny!!!!!
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That new shear map shows wind shear on the verge of 20 knots, 07L is already moving into the favorable shear.
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Quoting Hurricane009:
I commented on your blog!!! :)


I saw, thanks :)

Hydrus- where do you live?
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting hydrus:
1811-1812..Right in my back yard.....


And you are still there? Have you read the latest on the activity lately? It is becoming active again. And you live in tornado country as well. I heard Finland is nice. Are you near New Madrid? and I know it is pronounced Ma'drid not Madrid'.
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19:45 UTC
Member Since: June 9, 2007 Posts: 4 Comments: 15921
Atlantic Visible

Your kiddin' right? Look at how it "skips" thats strong shear IMO LOL Just an observation from an amateur.. ;)
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Shear, and Dry Air (arc clouds on the northern half of the circulation) still evident on satellite...

However, near the Center of Circulation, the low level cumulus clouds are becoming more prominent/cover more area.

This increase in low level clouds indicates moisture convergence at the surface, and typically portends a coming increase in convection... DMax into tomorrow morning when shear is forecast to come down a bit could be interesting!


NASA FRED FLOATER
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Quoting hydrus:
He is alive, he is dead, he is open, he is closed......yyyaaaawwwwnnn!


Fred is: Schizofredic
Member Since: June 28, 2006 Posts: 25 Comments: 8360
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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.