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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Okay now, don't blast me, but as a non-professional I don't understand why FredEx would not get better organized and strengthen IF the sheer drops AND he hits the warm SSTs in the Bahamas and the Gulf Stream. What would prohibit that from happening?
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Oh oh! Orange circle in the MDR, not good news. Looking for peace and quiet down wind of that Orange stuff.
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Quoting Patrap:
Glen Beck just announced on the Radio that wunderbloggers are fleeing the S Florida Coast from FredEx..!

The End must be near..


LOL xD are you serious???

btw its Glenn Beck :P.
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Quoting TheCaneWhisperer:


12Z BAMMS



yes I am aware that they are still running the models, that doesnt change the fact that the circulation at this time is weaker than it was last night.
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Quoting jeffs713:

Not to mention the incredibly dry air that is completely surrounding quasi-Fred.


Currently there is dry air intrusion in the northern semicircle particularly the NE quadrant but moisture will continue to gradually increase as "Fred" moves WNW.
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Quoting jeffs713:

Not to mention the incredibly dry air that is completely surrounding quasi-Fred.


Like that name quasi-Fred! Much better than Ex-Fred, or open-wave Fred. Gives him a little status but not too much importance. Good name.
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Quoting TampaSpin:


The trough to the East of Florida is lifting out quickly and being replaced by High pressure. I guess i can't tell my thoughts without being accused of over-hype. To say that a TS Fred will possibly hit South Florida is not over-hyping.....SORRY if those of you think so.......This is the last time i post to a blogger that can't take a post without not disagreeing but, critizies a post without any reason why!


The hitting of S Florida wasnt what I was calling overhyping, it was your statement about rapid intensification
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Quoting Grothar:
Fred is back on the Navy site as 07L. Can anyone answer if it is back to TD status, or are they just keeping it active since it is getting closer to land?


Is not a TD yet... at least QS doesn't quite show a persistent closed low.
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Well Hello,
Seems EX Fred has decided to come and say hello this weekend!
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Quoting jeffs713:

You're kidding, right?

Unless you had already planned on going on vacation this weekend or something... I think its rather silly to evac before a storm is even designated as a TS.
yeah i am just messing around... i like a little breeze so long as it doesnt knock out the directv
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Quoting Patrap:
Glen Beck just announced on the Radio that wunderbloggers are fleeing the S Florida Coast from FredEx..!

The End must be near..


Glenn Beck would also write that Drew Brees is from the planet zorcon and has extra muscles in his arms to allow him to throw so well lol
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Quoting TampaSpin:
What i really don't like is the anti-cyclone in the Bahamas that Fred is about to encounter...We could very well have a very quickly intensifing FRED!
Kinda floating on that island by yourself. You also show it skirting the keys on your map. Good luck with that forecast.
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Quoting BurnedAfterPosting:


the yellow circle came back and the models were run last night after the circulation closed itself off; since than it has again opened up to just a tropical wave and the pressure is a high 1013mb. The recon flights are precautionary; they have done that a few times this year just in case they need to.


12Z BAMMS

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Quoting TheCaneWhisperer:


It gained the attention of the NHC today didn't it. It prompted the scheduling of flights into it right? I think that would be classified as being better organized don't you??


The trough to the East of Florida is lifting out quickly and being replaced by High pressure. I guess i can't tell my thoughts without being accused of over-hype. To say that a TS Fred will possibly hit South Florida is not over-hyping.....SORRY if those of you think so.......This is the last time i post to a blogger that can't take a post without not disagreeing but, critizies a post without any reason why!
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That being said, of course Ex Fred could regenerate, but the fact is the circulation is weaker now than it was last night.
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Thanks for the synopsis StormW. A lot of dry are for both systems, then!
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Nice new publication from the NHC TROPICAL CYCLONES OF THE NORTH ATLANTIC OCEAN, 1851 – 2006 (pdf 16M). Includes tracking charts for each year, formation by month and 10 day interval. Good reference source.

Higher resolution versions are available 85M pdf, 416M pdf
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274. JRRP

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Fred is back on the Navy site as 07L. Can anyone answer if it is back to TD status, or are they just keeping it active since it is getting closer to land?
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Quoting TheCaneWhisperer:


It gained the attention of the NHC today didn't it. It prompted the scheduling of flights into it right? I think that would be classified as being better organized don't you??


the yellow circle came back and the models were run last night after the circulation closed itself off; since than it has again opened up to just a tropical wave and the pressure is a high 1013mb. The recon flights are precautionary; they have done that a few times this year just in case they need to.
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Quoting jurakantaino:
What is this guys problem with the Spanish language, this blog is mostly in English but since hurricanes first faces large Spanish speaking Island if we want to post information to our fellow citizen in our mother language is not of your business,


Thanks! You do understand!
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Quoting JupiterFL:


Me too. Headed to titletown to watch Meyer lay down the law.


Totally jealous :)
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Quoting BurnedAfterPosting:
also how is Ex Fred becoming better organized if it is now an open wave again; tells me its weakening, the low is very weak at 1013mb

So I wouldnt say its getting better organized and as StormW wrote any develop will be slow to develop and may not have time to amount to much


It gained the attention of the NHC today didn't it. It prompted the scheduling of flights into it right? I think that would be classified as being better organized don't you??
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Quoting BurnedAfterPosting:


TS while I respect that you are keeping an eye on Ex Fred and are defending those who are, lets be realistic. The low is weak; 1013mb and meeting up with the anticyclone is a big IF. You are overhyping it just a bit


Ok....we shall see.....i have not called for a Hurricane...i do believe we will have at least a Tropcial Storm into South Florida....How is that over hyping....please explain!
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Quoting TampaSpin:


Nope your wrong Space Mountain at Disney will tear it apart!

Maybe, but watch out in Windermere for the gap winds between the two mountains.
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Quoting palmbaywhoo:
i for one will not be waiting to see what happens, i am packing up and leaving the coast tonight!


Me too. Headed to titletown to watch Meyer lay down the law.
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Quoting BurnedAfterPosting:


TS while I respect that you are keeping an eye on Ex Fred and are defending those who are, lets be realistic. The low is weak; 1013mb and meeting up with the anticyclone is a big IF. You are overhyping it just a bit

Not to mention the incredibly dry air that is completely surrounding quasi-Fred.
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Quoting TampaSpin:
What i really don't like is the anti-cyclone in the Bahamas that Fred is about to encounter...We could very well have a very quickly intensifing FRED!


TS while I respect that you are keeping an eye on Ex Fred and are defending those who are, lets be realistic. The low is weak; 1013mb and meeting up with the anticyclone is a big IF. You are overhyping it just a bit
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Quoting palmbaywhoo:
i for one will not be waiting to see what happens, i am packing up and leaving the coast tonight!

You're kidding, right?

Unless you had already planned on going on vacation this weekend or something... I think its rather silly to evac before a storm is even designated as a TS.
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also how is Ex Fred becoming better organized if it is now an open wave again; tells me its weakening, the low is very weak at 1013mb

So I wouldnt say its getting better organized and as StormW wrote any develop will be slow to develop and may not have time to amount to much
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What i really don't like is the anti-cyclone in the Bahamas that Fred is about to encounter...We could very well have a very quickly intensifing FRED!
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I'll give it to xfred at least he has convection on the sw side...
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i for one will not be waiting to see what happens, i am packing up and leaving the coast tonight!
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Quoting TampaSpin:


BOOM
overhype!!
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Ok Mr. Sulu......Time to exit the Blog until things cool down again...Let's head over towards Ex Fred to see what happens with that naked swirl over the next few days ..Engage....Poof...
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Quoting TheCaneWhisperer:
Another thing to keep in mind, as Fred becomes better organized today, is that shear is not supposed to let up for 24 to 36hrs. Wonder what's going to happen when the shear lets up?


BOOM
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Fred will probably look better than 98L. 98L is looking worse by every hour and it has a bunch of dry air to contend with on it's journey. 98L= another decoupled storm just like Ana and Danny. I am starting to wonder if there will ever be a decent window this season that provides low shear and absent dry air.
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Quoting TampaSpin:
Looks like Fred will be a Tropical Storm in 36-48hrs looking at the intensity models.
I would be willing to take that bet on the no way side.
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Another thing to keep in mind, as Fred becomes better organized today, is that shear is not supposed to let up for 24 to 36hrs. Wonder what's going to happen when the shear lets up?
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At least with the HH scheduled for Saturday, we know that the NHC is keeping a very close eye on past FRED who may resurface shortly.
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Quoting VortMax1969:
MODEL DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1123 AM EDT FRI SEP 18 2009



THE SPORADICALLY-CONVECTIVE REMNANT LOW FROM THE FORMER HURRICANE
NAMED FRED...
THE NAM HAS TRENDED WEAKER WITH THIS PERSISTENT SYSTEM OVER ITS
PAST DAY OF RUNS...BUT KEEPS FREDS SURFACE CIRCULATION INTACT. IN
CONTRAST...THE ECMWF HAS BEEN CONSISTENT ON ITS DEPICTION OF THIS
SYSTEM AS AN EASTERLY WAVE MOVING INTO FLORIDA ON MONDAY DURING
ITS PAST COUPLE DAYS OF RUNS. DESPITE HAVING LIMITED DEEP
CONVECTION OVER THE PAST WEEK...THE CYCLONE IS WELL-DEFINED ON
SATELLITE IMAGERY AND HAS BEEN REMARKABLY PERSISTENT...WHICH
FAVORS THE NAM. HOWEVER...THE NAM IS SLOWER THAN THE REMAINDER OF
THE GUIDANCE WITH THIS SYSTEMS PROGRESSION. PER THE SYSTEMS
CURRENT MOTION VECTOR AND ITS EXPECTATION TO TRAVEL QUICKER WITH
THE LOW LEVEL FLOW...WILL FAVOR A TRACK WHICH BRINGS FREDS REMNANT
LOW PRESSURE AREA TO THE SPACE COAST OF FLORIDA MONDAY MORNING...
ESSENTIALLY A STRONGER VERSION OF THE 00Z ECMWF...WHICH COULD
BRING LOCALLY HEAVY RAINFALL TO EASTERN FLORIDA. SEE THE QPF
DISCUSSION/GRAPHICS ISSUED BY 21Z FOR MORE INFORMATION ON THE DAY
3 RAINFALL FORECAST FOR FLORIDA.


Indeed... I've been noticing NAM flip/flop between a stronger and weaker low... but yet keeping its spin. Should be interesting to see in actuality how Fred's remnants behave over the weekend.
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Quoting proroller:
197. jeffs713 3:35 PM GMT on September 18, 2009

Quoting StormChaser81:


Im confused all your ever post is spanish now, why not save us the time going through your post and dont post that stuff.


Or just not post at all...
Or just post pertinent information in English...



Who guys are you to say what this guy needs to do....first If he wants to write in Spanish that is his business not yours JEFF713 and STORMCHASER81
What is this guys problem with the Spanish language, this blog is mostly in English but since hurricanes first faces large Spanish speaking Island if we want to post information to our fellow citizen in our mother language is not of your business,
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Yea TS and Reedzone I agree,

I laugh hard every single time I think back to what it would have been like if this blog existed back when Andrew was around.

On August 19th, 1992; Andrew was weak and diffuse. If it had been discussed on this blog; 90% of the posts would have pertained to how Andrew was either a FISH or RIP and also blasting others who felt it still had a chance. Mixed in 10% of level headed people that realize that while not everything develops, things unexpected happen in the tropics and to never take your eye off things.

Oh and what happened to that storm named Andrew anyways? lol


Either way that is what is going on now; no one has said Ex Fred would be a hurricane or where it would hit, they are just looking at the possibility of regeneration; which is not at all out of the question given the conditions up ahead. Yet we get so many that just blast people for following up on things they feel are DEAD. Just because their opinion is different, doesn't mean its wrong.

All this being said, its still a wait and see game from Ex Fred; which by what I see is the tone that is being set by most on here. No one is saying this is going to be a major hurricane hitting the US, that is something being conjured up by people who feel even watching ex Fred is ridiculous; so they post a complete overreaction by saying people on here think Fred will be a CAT 5, which is clearly not being said at all. The drama comes from those who lash out at people following the tropics, not the other way around.
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Looks like Fred will be a Tropical Storm in 36-48hrs looking at the intensity models.
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Quoting StormChaser81:

Well if you where on this blog for awhile you would see why I said something. I think WS has a new friend.


You haven't answer the question...Who are you? The blog's owner? lol This is America freedom of speech.
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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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