Invest 94L and the Lesser Antilles

By: Dr. Jeff Masters , 9:51 AM GMT on August 30, 2009

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Hi, this is Dr. Rob Carver filling in for Dr. Masters. The convection associated with Invest 94L has intensified, prompting the NHC to issue an early Tropical Weather Outlook to update the situation. Essentially, people in the Lesser Antilles need to start paying attention to the seas and skies. Looking at the computer track models, the set of model solutions are fairly similar to the Saturday model runs. A set of dynamical models (GFDL, HWRF, NOGAPS) runs to the NE of the Antilles, while the simpler models (LBAR, BAM family) are more easterly and take 94L over the Antilles. I do not ascribe any significance to the 00Z GFS track following the simpler models over the dynamical models. From my examination of the 00Z GFS run, it looks like the simulated 94L weakens too much, so the automatic vortex tracker picks up another vorticity feature. As for the future of 94L, there is a large area of large wind shear to it's north. It will need to keep it's track at WNW-W for intensification.

Update at 6AM EDT
I would be remiss if I didn't mention the major hurricane in the Eastern Pacific, Jimena At this time, Jimena has a satellite-estimated maximum wind speed of 115 mph, making it a Category 3 storm on the Saffir-Simpson scale. Jimena has an impressive presentation in satellite imagery with a large area of cold anvil cirrus in the center of the storm. The following microwave imagery indicate the formation of a relatively potent central eyewall, which is responsible for intensification.


Fig. 1 SSMI 85 GHz PCT at 0244Z Aug 30. Image courtesy of NRL.


People along the western coast of Mexico and along along the Baja need to pay close attention to this dangerous storm. I emphasize that using the current track and intensity forecast, Jimena will be a Category 4 storm when it approaches the tip of Baja and a Category 3 storm when it makes landfall up the coast.

It is worth noting that if Jimena follows the more easterly tracks presented in the computer track forecasts, the remnants of Jimena could impact NM and western Texas.


I'll update this entry further in response to 94L's development.


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Quoting nrtiwlnvragn:
AL 94 2009083012 BEST 0 118N 463W 25 1007 DB


no surprise there.
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Quoting P451:


The 8AM discussion states the low is at 11N 44W.

It's consistently been to the right of the convection throughout it's life as an invest.

This is in fact the closest any organized convection has been to the low pressure area however so it is getting more organized.


Thats an issue then aint it? :p
Because its at 45 W per WU. Note at the end of the TWD it says 'medium' instead of what 94L is at, high. These things are written at 2 AM surface data.
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There is no true center with this yet which is why trying to pin point exactly where it is is probably a waste of time. Developing lows have broad, and sometimes very broad, areas of low pressure located " near " certain coordinates.

If you look at the TWD the low is stretched out over a set of coordinates "near" and not "at" a particular position. Having said that, 94L has moved W some since the TWD was written.

Anyway I will be back late this afternoon.
Have a good morning all
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AL 94 2009083012 BEST 0 118N 463W 25 1007 DB
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06z GFS Shear
84 hours
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151. Relix
My prediction was spot on in the sense that I suggested yesterday it would become a TD by this afternoon and a possible minimal TS by the night. I don't trust the NW models that much and I feel it will pass too close to comfort or ever over us in the Antilles. Puerto Rico has to watch out for this!!!


EDIT: Well I sounded like a news reporter =P. Just woke up! Good Morning WU!!
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Not sure if these are exactly up to date, but err.. several issues with this, I'll name one that the models have it going in a WNW direction when its going very much west.. I'll let you name the second one rofl.

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Quoting SLU:


Morning sir!

Yes I agree with you on that. Still no NW shift.


Well thank you. I just dont want anyone saying I want 94L to hit land and not go out to sea. That is a bad stain to give someone.

I never thought Danny nor Bill would impact land, i try to be as objective as possible. But given 94L's location, it isnt another Bill.
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one of the biggest vacation areas for americans is about to get wiped off the map and were talking about a joke in the central atlantic r.i.p to cabo
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The NHC/TPC

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Before I head out for a while again and not post much... here's some thoughs:

Current 09Z steering flow will keep the system down on a general W track for the time being today... and I do believe that ECMWF is currently the best solution given the current setup as long as the system does not gain deep enough convection and stacking to start feeling that more NW type track as depicted by HWRF.



Finally, the disturbance on the S Carib. will need to be watched if it persists as there's currently little movement to it and the TUTT to its NW which as been enhancing its convection could assit it in gaining some latitude.

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142. SLU
Quoting Weather456:
Center appears to be near 46-48W near 11N


Morning sir!

Yes I agree with you on that. Still no NW shift.
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Quoting bajelayman2:


Dry air does not seem to be near as much as the earlier systems had to deal with?
True that..However there are a couple of big upper level lows that are ready to stuff 94L's running game....
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Quoting PensacolaBuoy:
Doesn't it bug you that the 8:00AM TWO says 94L has a HIGH chance of becoming a cyclone, while the TWDiscussion issued at the same time says MEDIUM chance. I guess 456 wrote the TWO, and Ike wrote the discussion!


the TWD is actually based on surface data at 2AM. Also the 8am TWD is oftern issued well before 7am.

8am Outlook is issued much later.
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137. Relix
Hey I was almost spot on haha. Possible for it to develop as a TD today. In see it also gained some latitude. Guess us in the Antilles have the first threat in a long time (Ana was nothing and Bill was going out). Is the current movement W-WNW?
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94L's current position per WU.
11.2N 45.1W
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135. SLU
Quoting P451:
As what seems to have been the norm this season: Another very lopsided system.



Low center marked by red dot.



The center is near the deepest convection somewhere near 11n 47w.
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134. IKE
Quoting bajelayman2:
Ike and 456, two cool, GOOD GUYS. I listen to y'all, you know your stuff.

Listen to another respectable person, Kaymanislander, he is correct.



I'm no expert...have never claimed to be. Take the advice of the NHC which has never stated, yet, that the islands will "feel some impacts from 94L". They may state that in the future. Time will tell.
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Quoting kmanislander:


Quikscat show nothing near 44W. The system has moved on from there.


Yea, some reason that TWD is behind, its the position that 94L was at hours ago, note the 'Medium' chance for development at the end when the most recent TWO gives it a 'High'.
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Center appears to be near 46-48W near 11N
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Doesn't it bug you that the 8:00AM TWO says 94L has a HIGH chance of becoming a cyclone, while the TWDiscussion issued at the same time says MEDIUM chance? I guess 456 wrote the TWO, and Ike wrote the discussion!
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Have a good day all, going to cut my lawn.
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I looked at the models, all of them have 94L going NW or a very WNW direction right now. 94L is going straight west.
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Quoting P451:
805AM AN ATLANTIC OCEAN TROPICAL WAVE GOES FROM 16N42W TO A 1009 MB
LOW PRESSURE CENTER NEAR 11N44W TO 7N49W MOVING WEST 15 TO 20 KT.
STRONG SHOWERS AND THUNDERSTORMS ARE FROM 10N TO 13N BETWEEN
45W AND 48W. ISOLATED MODERATE SHOWERS TO LOCALLY STRONG
THUNDERSTORMS ARE ELSEWHERE FROM 10N TO 17N BETWEEN 40W AND
50W...AND FROM 7N TO 11N BETWEEN 50W AND 57W IN WHAT APPEARS
TO BE POSSIBLY ITCZ PRECIPITATION THAT IS BEING ENHANCED AND/OR
PUSHED NORTHWARD BY THE LOW CENTER/TROPICAL WAVE SYSTEM. THE
CHANCE FOR THIS SYSTEM TO BECOME A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS IS MEDIUM.

=



WV Loop closeup:




WV long range: What does everything think of the feature pushing southward towards PR? Is this what the models see when they pull 94L northward?



Quikscat show nothing near 44W. The system has moved on from there.
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127. ackee
Quoting stormpetrol:
If anyone thinks this is going move North of the Islands , well they better think again, while models are used for guidance and are sometime fairly accurate, nothing is grounded in stone.94L should have been near 20N already according to most of the models, this system is too far south , it would have to move NW/nnw now to miss the Islands imo., even a true WNW movement & the northern would get a direct impact, jmo.
agree
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Quoting P451:
As what seems to have been the norm this season: Another very lopsided system.



Low center marked by red dot.



I dont think thats the center or it wouldnt have a red circle.
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Quoting chucky7777:
94L has got a lot working against it if it wants to survive.......just my opinion. Dry Air and ULL's all over the place.look at the WV loop......Link


Dry air does not seem to be near as much as the earlier systems had to deal with?
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Thanks for the update 456
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108. Sorry, quote function currently inoperative. There's 20 and then 30 knts of wind shear currently ahead of it. I don't know how quickly the shear picture changes, but if it goes into 30 knts, it will weaken and become disorganised again. Looks like a roller coaster ride, but if it doesn't track N like the more sophisticated models say, then it could get big and dangerous.
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121. SLU


Latest quikscat still shows the center near 11n. Still not much of a northward component. Look at the large windfield too.
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P451, that TWD even though it was issued at 805 AM, is behind, note how it gives it a medium chance for development when the TWO gives it a high.
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Organizing pretty well

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94L has got a lot working against it if it wants to survive.......just my opinion. Dry Air and ULL's all over the place.look at the WV loop......Link
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Quoting ssmate:
Good Morning Kman. Hit em straight today. I'm off to play hockey. That's the difference between the 1,500 miles ot so bewtween us.


Good morning to you too. Geography is everything eh ? LOL

94L ramping up but still slowly. 55W is a "sweet spot" for developing systems so I think it should keep improving as the day wears on
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If anyone thinks this is going move North of the Islands , well they better think again, while models are used for guidance and are sometime fairly accurate, nothing is grounded in stone.94L should have been near 20N already according to most of the models, this system is too far south , it would have to move NW/nnw now to miss the Islands imo., even a true WNW movement & the northern would get a direct impact, jmo.
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Tropical Update
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Ike and 456, two cool, GOOD GUYS. I listen to y'all, you know your stuff.

Listen to another respectable person, Kaymanislander, he is correct.

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Good Morning Kman. Hit em straight today. I'm off to play hockey. That's the difference between the 1,500 miles ot so bewtween us.
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I go with you, into the Caribbean.

I too thought yesterday, that it was a goner.
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A friendly reminder to all. As the blog will likely be very fast today Admin tends to monitor busy days and bans will probably be handed out for bickering.

If you want to be around to take part in the unfolding of events try to be civil and respect the opinions of others.

At some point in the next 48 hours everyone blogging here will likely be wrong about something going on out there.

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I gotta go for now. Ike and 456, you play nice. I for one, respect both of your opinions, as I'm sure many here do. Catch you cats later...
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I am but a lowly layman, forgive me. But I just looked at the satellite loop and it looks to me to be heading twoards Barbados, will pass on or around, then into Caribbean.

Something like an Ivan track, though weaker at the moment.

How fast do y'all expect intensification?

This is the closest to the islands yet, particularly us in Barbados.
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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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