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Tropical depression likely by Tuesday in Western Caribbean

By: Dr. Jeff Masters, 8:45 PM GMT on October 08, 2007

A vigorous surface circulation has developed in association with a broad area of low pressure over the Western Caribbean (94L). A pass from the European ASCAT satellite at 11:02 am EDT showed that the surface circulation had gotten much less elongated, compared to this morning's QuikSCAT pass. Top winds were only about 10 mph in the 11 am ASCAT pass, but have no doubt increased since then. Satellite loops show a very large surface circulation covering the entire Western Caribbean, with a concentrated area of thunderstorms forming near the center of circulation. Surface pressures remain very low over the entire Western Caribbean. Wind shear is less than 10 knots, and is expected to remain less than 10 knots through Thursday. It is likely that this system will form into a tropical depression on Tuesday, despite the very large amount of atmosphere it is trying to spin up.

Steering currents are weak in the Western Caribbean, but most of the models show a slow motion to the west or northwest that will take 94L over Belize or Mexico's Yucatan Peninsula by Thursday. It is unlikely 94L will have time to become a hurricane before it moves over the Yucatan, and the main threat from the system will be heavy rain. These rains may cause significant flooding problems in Belize and Mexico's Yucatan. Heavy rains may also affect northeast Guatemala, but should not cause significant flooding.

There is a strong trough of low pressure forecast to swing across the U.S. this week, which could turn 94L northwards into Western Cuba, the Florida Keys, or Southwest Florida. However, this is unlikely, since none of the reliable computer models are forecasting such a turn.

It is likely that 94L will eventually emerge into the Gulf of Mexico or Western Caribbean after spending a few days over the Yucatan. When it does so, it will probably be intact enough to re-strengthen, since it is such a large system. Its long-term fate it highly uncertain, as the steering currents are weak and the storm's intensity will be controlled by interaction with land.

Elsewhere in the tropics
A nearly stationary tropical disturbance a few hundred miles north of Puerto Rico is generating a large area of thunderstorms. The region is under 15-20 knots of wind shear, due to strong upper level winds from the west. These winds are blowing the heavy thunderstorm activity downwind, to the east of the elongated surface circulation apparent on visible satellite imagery. Wind shear is expected to remain 15-30 knots over the region over the next three days. The high shear should discourage any significant development.

I'll have an update in the morning.

Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

Morning! Nice pictures of Wilma' Surge. Dean inded did was not the wavemaker Wilma was. Keeping an eye on 94L, I don't want any trouble from this one, but it would be nice to get at least one more swell maker for the Gomex. Presently, I am not too hopeful
Good morning everyone, when looking at the water vapor loop I noticed all the dry air pushhing into the GOM. Dumb question, is that from the trough that Stormw and all were talking about yesterday?
The 00z GFDL has 94L making a tight loop and ending up right back where it started.
nash, this is a couple runs in a row the GFDL has shown that.... the 00z CMC shows about the same.....
7.Do not "1st!", "1st post!", or any of the numerical/linguistic derivatives. This is a worthless use of blog space.

6.No comments that contain only personal notes such as, "Good Morning!", or "You've got mail, X".
For what it is worth, AccuWeather is saying that 94L will not develop into a TD. In this rare case I have to agree with them. Thunderstorms are on the decline this morning and it is only about 75miles off shore.

Last night at 10:50, Dr. Lyons said that 94L will not have any future impact on the U.S. due to a blocking high. Much like we saw with our previous storms.
good morning all, I see 94l still trying to get his act together,and anybody see that low in the north atlantic wrapping up
Taz relax! was just trying to see if my photo was up!!!!
Dont hope too much surf mom might get more swell that we can handle. Noone knows for sure what 94 will end up doing.
If 94L does loop around and re-emerge, it could still be a player......
94L is going to mx that all you need to no has i been saying for the past few days wind shear is going up has well and it olny has a ch of a TD at land fall in mx no stronger then that
NEwxguy I have been watching the North Atlantic Low all morning. Wait till later today7 when a new Low currently off the Mass coast spins up. OPC calling for Hurricane force and all the models for some reason are showing it going warm core and bombing to 967mbs
508. Tazmanian 1:08 PM GMT on October 09, 2007 Hide this comment.
7.Do not "1st!", "1st post!", or any of the numerical/linguistic derivatives. This is a worthless use of blog space.

6.No comments that contain only personal notes such as, "Good Morning!", or "You've got mail, X".

Way too much time on your hands dude.

Marine Weather Discussion
Second that number 1 fan. This system might be down there for a while. Dr Grey said at the beginning of the month there would be one more major. Well?
looks like the E coast could have a late season hurricane
Good morning,

Doesnt look like anythings going to come of 94L anytime soon. Boy, the models sure are on a role in their predictions......
bonedog,I've never seen a system go warm core in the north atlantic,I would assume that is extremely rare
Thanks Leftovers --I know the "be careful what I wish for lesson". Dean was great (but I felt guilty for the Mexicans) 90L was very sweet, beautiful glassy southie wavemaker and it di not cause anyone any trouble --that is the kind I like.

Last night you were looking for models of the pacific off the west coast.


thats why i said for some reason. I mean it has it going warm core NORTH of Labrador. Unless some wierd act of God has happened the waters up there are only 14 to 17C I dont even think and extratropical system could pull a warm core with those temps.

Just saying what the models showed. But will be a system to watch nontheless even if it stays extratropical. Any 967mb storm should be awsome to see
529. IKE
Taz, isn't "Thanks" as worthless as "Good Morning"?