Lesser Antilles wave a threat to become a tropical depression

By: Dr. Jeff Masters , 2:23 PM GMT on August 09, 2006

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A tropical wave moving westward at 15-20 mph near 13N 57W, about 300 miles east of the Lesser Antilles Islands, has made a significant comeback this morning after losing its spin and most of its heavy thunderstorm activity last night. The system has re-gained its spin, and a new blow-up of intense thunderstorms has developed over the circulation center. It remains to be seen if the storm can hang onto this thunderstorm activity; 10-20 knots of wind shear are still interfering, and this system has had a history of alternately looking organized, then disorganized, as the shear waxes and wanes. Strong upper-level westerly winds from an upper-level low pressure system to the north are responsible for this shear, and this low is expected to continue to bring significant amounts of shear over the system for the next two days. It is possible that the shear may weaken enough to allow a tropical depression to form in the next day or two, but it will be a struggle for this system to get organized. Pressures are falling at the two buoys about 100 miles to the north of the storm's center, though, and peak winds at 9am EDT at one of these buoys was a sustained 28 mph. We don't have a recent QuikSCAT satellite pass to judge the winds that way, unfortunately. There are the beginnings of some upper level outflow apparent on satellite imagery, but no real low-level spiral banding occurring yet.

The wind shear is greatest to the system's north, so the further south it stays, the more likely it is to develop. The Saharan Air Layer (SAL) of very dry air is 100-200 miles to the system's north, which is probably far enough away that it will not impact it over the next day or two.

Last night's GFDL model predicted that the wave will develop by Thursday into a weak tropical storm, which will move through the Caribbean Sea to a point south of Haiti on Saturday, where high wind shear will dissipate it. None of the other computer models develop the storm at all.

The wave should move through the Lesser Antilles Islands tonight and Thursday morning, bringing winds of 30-40 mph and heavy rain to Barbados, St. Lucia, Martinique, and surrounding islands. Puerto Rico may get socked on Friday with these conditions, and the Dominican Republic on Saturday. The Hurricane Hunters are on call to investigate the wave today at 2pm EDT today, and I'll have an update this afternoon on what they find.


Figure 1. Preliminary model tracks for the mid-Atlantic tropical wave.

Elsewhere in the tropics
Clouds and showers stretching from the Bahamas through South Florida are associated with an upper level low pressure system. High wind shear, dry air, and cool air temperatures are expected to keep this area from developing. A broad non-tropical low pressure system located about 800 miles southwest of the Azores is drifting southward, and is not expected to develop over the next two days. Some of the computer models are forecasting that development is possible by Sunday or Monday, though.

Jeff Masters

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872. a654321r
9:21 PM GMT on August 09, 2006
Does Barbados have a radar with a link?
871. StLucieHurricane
8:01 PM GMT on August 09, 2006
StormTop, are you a gambling man???? i will put a hundred dollars that a hurricane will form in August! Want to take that bet ? we can use paypal LOL!!!
870. robinvtx
8:00 PM GMT on August 09, 2006
thanks so much.
868. Crisis57
7:59 PM GMT on August 09, 2006
so are we thinking TD at 5pm
867. thelmores
7:58 PM GMT on August 09, 2006
penn state models page

fsu models page
Member Since: September 8, 2005 Posts: 0 Comments: 3805
866. NaplesPatty
7:57 PM GMT on August 09, 2006
Robin here are a few model links


Link

Link

Link
865. thelmores
7:56 PM GMT on August 09, 2006
robin..... look at the top of this blog in Dr. Masters post....... you can see model tracks there......
Member Since: September 8, 2005 Posts: 0 Comments: 3805
864. robinvtx
7:50 PM GMT on August 09, 2006
link to models please. i know where to get on nhc website after depression forms. thanks
863. KRL
7:50 PM GMT on August 09, 2006
Great update! Thanks!!

Loving these high pressure systems to keep these things out of Florida!
Member Since: July 31, 2006 Posts: 0 Comments: 231
862. bocahurricane
7:48 PM GMT on August 09, 2006
Pip- that was funny :)
Member Since: July 6, 2006 Posts: 0 Comments: 75
861. Barbados
7:47 PM GMT on August 09, 2006
60-70mph sound extremely high for just a tropical disturbance.
Member Since: August 9, 2006 Posts: 0 Comments: 253
860. Randyman
7:43 PM GMT on August 09, 2006
Tropical Disturbance 28 Continues to Organize
Updated: Wednesday, August 9th 2006 2:34pm CDT
Tropical Disturbance 28 continues to become better organized this afternoon about 100 miles east of Barbados near 13.3N/58.1W, moving west at 20-25 mph. Even though there is a well defined mid level cyclonic circulation evident on satellite, the latest reconnaissance reports indicate that it has not built done to the surface, so at least for the time being this will not be classified as a tropical depression. However, based on the latest trends, we do think this system could be declared a tropical depression later this afternoon or evening. Regardless if a depression does form later today or tonight, locally heavy rain and gusty winds up to 60-70 mph will be spreading across the northern Windward and southern Leeward Islands, mainly in between the islands of St. Vincent and Guadaloupe this afternoon through tomorrow morning. The mid level center will probably pass close to the Island of St Lucia around midnight tonight.

As for the track, steering patterns suggest that high pressure will remain to the north of this system for the next week. This should keep the disturbance tracking generally to the west or west-northwest through next weekend. Our forecast takes it into the eastern Caribbean Sea early tomorrow, then westward to near the north coast of the Yucatan Peninsula, possibly as early as Monday August 14th, and finally inland across southern Mexico during the middle of next week. Due to the strength of this high pressure area, any threat to the northern Gulf appears to be very low at this time. It does appear wind shear will be increasing across the Caribbean, so any short-termed organization that may occur over the next 24-48 hours may be short lived if the projected wind patterns remain over the Caribbean this weekend.

We will continue to track this weather system very closely in the upcoming days.

Meteorologist: Fred Schmude
Member Since: July 26, 2005 Posts: 0 Comments: 222
859. Thundercloud01221991
7:40 PM GMT on August 09, 2006
Will that convection stay going after it loses its heating just because it gets sucked into the storm
Member Since: August 1, 2006 Posts: 28 Comments: 3716
858. Pipsneyy
7:33 PM GMT on August 09, 2006
The Funniest Thing Ever


Since everyone is so hipped up about these new computer models, i say we take a little break and let 91L get its act together again. Watch that above and youll get a laugh out of it.
857. Skyepony (Mod)
7:32 PM GMT on August 09, 2006
387
URNT11 KNHC 091859
97779 18564 40140 60008 03100 11025 26179 /0010
40915
RMK AF302 01DDA INVEST OB 12
;

25kts flight level

interpolator~ Yes that would be expected during the day, particulairly if the island got a good bit of sun on it before the storm showed up that day.
Member Since: August 10, 2005 Posts: 209 Comments: 39113
856. STORMTOP
7:31 PM GMT on August 09, 2006
tshizzle i agree with you like i have been saying all alnong nothing will develop in these hostile conditions...it was a waste of time to send a recon plane down there..StormTop
855. Pipsneyy
7:29 PM GMT on August 09, 2006
They are models! They probably will turn way north again at 8 or 2. They change every time
852. jcpoulard
7:25 PM GMT on August 09, 2006
My prediction for this system is that :
Tropical Strom to night.
Huricane Cat tomorow morning and treath Haiti and Dominican Republic.
Make Land Fall a the south of haiti late friday or saturday morning as cat 2 ou 3.
Bad perspective......
Member Since: September 15, 2005 Posts: 4 Comments: 114
851. Interpolator
7:24 PM GMT on August 09, 2006
newbie here just wondering if when it moves over the small islands does that ever trigger some thunderstorm activity during the day.
850. Antivanity
7:23 PM GMT on August 09, 2006
SURPRISE?
Member Since: July 7, 2005 Posts: 0 Comments: 49
849. thelmores
7:23 PM GMT on August 09, 2006
"Maybe they are not seeing the message."

please sir.... i am not that nieve! LOL
Member Since: September 8, 2005 Posts: 0 Comments: 3805
848. hurricaneman23
7:23 PM GMT on August 09, 2006
what the hell just happend to every single model? they were way north and now ??? way south.
847. Barbados
7:21 PM GMT on August 09, 2006
Quakeman55. See moving radar link below.

Link
Member Since: August 9, 2006 Posts: 0 Comments: 253
845. thelmores
7:20 PM GMT on August 09, 2006
"thelmores; maybe you should send an email to everybody who posts their sites with that message in it if you don't want them posting their sites."

MichaelSTL, i do exactly what the admin asked.... hit the spam button! ;)
Member Since: September 8, 2005 Posts: 0 Comments: 3805
844. quakeman55
7:20 PM GMT on August 09, 2006
There's clearly spiral banding going on around it...anyone have a radar link? Especially a moving radar?
Member Since: March 31, 2002 Posts: 1 Comments: 1276
843. IKE
7:19 PM GMT on August 09, 2006
Gulfscotsman...whether it's a TD/TS or not...the islands are still going to get some rough whether.

Calm down and take a shot of scotch.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
842. quakeman55
7:19 PM GMT on August 09, 2006
It'll slow down pretty soon here...they usually do.
Member Since: March 31, 2002 Posts: 1 Comments: 1276
840. hurricaneman23
7:18 PM GMT on August 09, 2006
may have a chance? i thought it is almost sure to become a td by tonite or tomorrow?
839. cajunkid
7:18 PM GMT on August 09, 2006
the models are only as good as the info put in. I'm not saying they don't put in good info, just that we don't know all the variables. So they can't possibly be totally accurate. They might hit it dead on or they might whiff. We wouldn't all be in here if they could nail it.
Member Since: July 10, 2005 Posts: 3 Comments: 1281
838. whirlwind
7:17 PM GMT on August 09, 2006
hurricane23- is your "submit" button stuck???? thanks for the same post
837. rxse7en
7:17 PM GMT on August 09, 2006
Hurricane® is now my registered trademark. I will accept all royalties either in beer or plywood. Thank you and carry on.
Member Since: August 21, 2005 Posts: 0 Comments: 530
836. hurricane23
7:16 PM GMT on August 09, 2006
Guys i think the spin were seeing is Basically aloft this thing is racing at 30 mph....Developement will not happen unless it manages to slow because the lower half is racing along the low level ridge...and the mid level circ is lagging behind note the possible MLC that was left behind in vis imagery loops...If it manages to slow down and stack a little bit it may have some chance.
Member Since: May 14, 2006 Posts: 8 Comments: 13841
835. Pipsneyy
7:16 PM GMT on August 09, 2006
jphurricane2006, is it going to ride a high? whats around the atmosphere that is going to steer it
834. quakeman55
7:16 PM GMT on August 09, 2006
How in the damn stupid ass hell could it NOT have a closed surface circulation? I mean look at the visible! Clearly an excellent rotation going on there...no doubt.
Member Since: March 31, 2002 Posts: 1 Comments: 1276
833. Skyepony (Mod)
7:16 PM GMT on August 09, 2006
oops should have been more like far WNW side.
Member Since: August 10, 2005 Posts: 209 Comments: 39113
832. ricderr
7:16 PM GMT on August 09, 2006
Actually Story.....i have a problem with anyone posting something created by another and not giving them credit. I thought hurricane23 was involved womehow with the hurricane hunters...i thought i remembered a conversation between him and randrewl and just figured he had information that was privvy to him and not the general public..but after 2 or 3 posts about it...seemed to me that it took on a life of its own
Member Since: June 27, 2006 Posts: 676 Comments: 22276
831. hurricane23
7:16 PM GMT on August 09, 2006
Guys i think the spin were seeing is Basically aloft this thing is racing at 30 mph....Developement will not happen unless it manages to slow because the lower half is racing along the low level ridge...and the mid level circ is lagging behind note the possible MLC that was left behind in vis imagery loops...If it manages to slow down and stack a little bit it may have some chance.
Member Since: May 14, 2006 Posts: 8 Comments: 13841
830. Tazmanian
7:15 PM GMT on August 09, 2006
no TD yet i want my $ back lol well any way it look like we are looking at a cat 2 or 3 hurricane in a few day as it move in to the gulf
Member Since: May 21, 2006 Posts: 5091 Comments: 115437
829. whirlwind
7:15 PM GMT on August 09, 2006


Credit Colorado State University
(haha)

Im not buying this forecast
828. thelmores
7:15 PM GMT on August 09, 2006
for those that CONTINUE to "PIMP" their sites.....

"Posted By: WunderYakuza (Admin) at 3:55 PM GMT on August 08, 2006.
Some people have been spending a lot of time posting links to their own web sites over and over in this blog. This is spam. If the content of the comment itself does not give Wunderground users information in this blog or contribute to conversation in this blog, it is spam so please flag it.

Everyone has their own blogs on this site, in which we allow you to link to almost anything and write almost anything. That's the place for this kind of content, not here or in the other featured blogs where traffic is already quite high.

-Aaron"
Member Since: September 8, 2005 Posts: 0 Comments: 3805
827. hurricaneman23
7:15 PM GMT on August 09, 2006
does that mean no td by 5pm?
826. hurricane23
7:15 PM GMT on August 09, 2006
Guys i think the spin were seeing is Basically aloft this thing is racing at 30 mph....Developement will not happen unless it manages to slow because the lower half is racing along the low level ridge...and the mid level circ is lagging behind note the possible MLC that was left behind in vis imagery loops...If it manages to slow down and stack a little bit it may have some chance.
Member Since: May 14, 2006 Posts: 8 Comments: 13841
825. Pipsneyy
7:15 PM GMT on August 09, 2006
It could turn anywhere Relix, its not riding anything right now. We have to wait and see what will happen in about 3-4 days.
824. JustSouthofEquator
7:14 PM GMT on August 09, 2006
I think the last post said that the circulation is aloft Thundercloud1221991
Member Since: June 3, 2006 Posts: 0 Comments: 190
823. Barbados
7:14 PM GMT on August 09, 2006
Barbados1. Are you in Fosters?
Member Since: August 9, 2006 Posts: 0 Comments: 253

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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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