Lesser Antilles may see a tropical storm late this week
A concentrated area of intense thunderstorms near 9N 36W, midway between Africa and the Lesser Antilles Islands, has become more organized this morning. NHC has labeled this system Invest 91L, and is giving it a 60% chance of developing into a tropical depression by 8am Tuesday. Wind shear is a moderate 10 - 20 knots, sea surface temperatures are at record highs, and the dust and dry air of the Saharan Air Layer (SAL) are far enough to the north of 91L to potentially allow further development. The main negatives for development are the current phase of the Madden-Julian Oscillation, which favors downward motion over the tropical Atlantic, and the fact that 91L is too close to the Equator to take much advantage of the Earth's spin to get spinning. Last night's ASCAT pass of the region did show a large region of westerly winds south of 91L, indicating that a surface circulation is trying to form. Satellite imagery shows that the intensity and areal extent of 91L's heavy thunderstorms is increasing. However, there are no signs of a surface circulation, and low-level spiral bands and upper-level outflow are not apparent yet.
Forecast for 91L
There is strong model support for 91L developing into a tropical depression. The GFS, ECMWF, NOGAPS, and UKMET models all develop 91L into a tropical depression by Tuesday or Wednesday. A west to west-northwest motion is predicted, and residents of the Lesser Antilles Islands should anticipate the possibility of a tropical storm arriving in the islands as early as Thursday. It is possible that 91L would pass northeast of the islands, as predicted by the UKMET model, and it is too early to speculate on which of the islands is at most risk. As the storm approaches the Lesser Antilles late this week, 91L will encounter a strong upper-level low pressure system centered north of Puerto Rico. This upper-level low will likely bring high levels of wind shear to the waters just north of Puerto Rico and Hispaniola. Thus, if 91L stays to the south, in the Caribbean, it is far more likely to attain hurricane status than if it pushes north of the Caribbean. As always, long range forecasts of this sort are speculative, and it is too early to reliably say what the long-term risks of 91L becoming a hurricane are. The latest intensity forecast from the SHIPS model shows 91L peaking in strength four days from now, then weakening as it encounters the high wind shear area north of Puerto Rico.
Figure 1. Morning satellite image of Invest 91L.
Next update
I'll have an update Monday morning.
Jeff Masters
Reader Comments
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Thanks so much!! :-)
JFV version 100.1.1???
As far as 91L...I remember 90L and what the models had for it.
I said yesterday on here...I don't believe it until I see it anymore with this season. I didn't see a ULL on visible...I'll look at water vapor.
do i see a green circle above 91L, is that neutral or upward?
apparently you are the one that doesn't read. not one aspect of dr. masters post mentions florida
State your opinion and move on, if you have a different one say so - do not attack someone for theirs.
If you don't like a poster, put them on ignore. Otherwise I think the new feature - should get some use.
Well, I do agree with what you said, but 91L is 90L for the most part as Levi said last night. It is the same surface center.
Hurricane Ivan developed very low 8 degrees I believe.
evolved? what since I have been here? cause of my picture? whats so funny? please tell me because I didnt start this! I said nothing to either of you and we do have a mailbox you could have wrote me in... instead of trying to embarrassing me>...
Alright!
If only everyone WOULD follow your suggestion...this blog would be so much easier to follow!
Um, no.
WOAH ok look at yesterdays post...ask storm,levi and huricane09 the questions I ask and the answers they give me so.... you POOF
Hey don't worry about those idiots......look at me i'm ugly as hell and i get harressed also!
link
Shows the invest centered north of 10. Clouds are mostly south of the invest center.
When I got here, there were only 36 bloggers. That was over five years ago. We were all neutral.
It was funny when they added avatars to WU. Suddenly, we knew who was male and female, and believe me, we laughed a LOT at each other.
I wasn't trying to embarrass you. That's not my style. We gotta LONG week ahead of us.
Peace.
IKE- PLEASE FIND THAT ULL!!!
Thank you!!
popcorn and milkduds, Aussie.
Could be deja vu....Bonnie part 2.
Outflow boundaries can be seen on the northern side too.
Maps of PGI22L are outdated...the people who do send out the predict info are on a break today.
link
Shows an upper level anticyclone to the west of the invest. Develop would occur if/when the invest catches up with the anticyclone.
"Last night's ASCAT pass of the region did show a large region of westerly winds south of 91L, indicating that a surface circulation is trying to form. "
but then in the next sentence.....
". Satellite imagery shows that the intensity and areal extent of 91L's heavy thunderstorms is increasing. However, there are no signs of a surface circulation, and low-level spiral bands and upper-level outflow are not apparent yet."
The CIMSS site is up to date.
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