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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Hot off the press. If I am wrong then clearly I am in good company

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Quoting WeatherStudent:


hey there, good evening, my friend? how are you? i think that she'll eventually end up being a storm for the fishes only. where do you think she'll end up?


I do see it as a threat to a portion of the Islands...beyond that, have no idea. Way to early.
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Good night - I am out as well
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Quoting kmanislander:
I'm out for tonight. Catch you all tomorrow.
Goodnight.
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2850. Relix
Quoting jipmg:
since when was 94L moving due north? LOL


Well it definitely looked to move NW to me or maybe I am seeing things. Been watching this for 14 hours almost non stop. In fact... I am gonna hit the bed. Good night WU!!!
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I'm out for tonight. Catch you all tomorrow.
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I do not understand how anybody can think its going more N than W right now. It has been explained many times it just looks that way. If i can understand, anybody should.
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deleted
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Can’t wait till they designate it as a depression so we can read the discussions and see the forecast cones and figure out what is going on!
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I appreciate all of the knowledge that Storm W bings to the blog. MAny on here gain a lot from his posts. He is looked up to by most on here. Along with that respect and admiration comes adiitional responsibility. Everyone here reads his posts. Unfortunately, there are some that will think that if it is OK for storm to break the rules then it is ok for them. Infact, some idolize individuals like storm and may even attempt to mimic his beviour. This is a very unfortunate incident ans we will all pay the price for 24 hours. Being in "leader" like storm carries with it the additional responsibility of setting the standard and following the rules. This may not seem fair or right but unfortunately it is the way it is, not only on this blog, but in all aspects of life. While I hate what hapened and in no way mean this post to shed any negative light on storm, I do understand the admins' stance. Look forward to you getting back storm!
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2842. will40
sorry for double post
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2838. jipmg
since when was 94L moving due north? LOL
Quoting naplesdoppler:
Come on Admin, I know you are smarter than that. Use some logic.... I know there have been worse things. A lot of people come here to read StromW posts. Am I wrong WU bloggers??
StormW has his own page.Link. It's always a great source.
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000
WTPZ43 KNHC 310238
TCDEP3
HURRICANE JIMENA DISCUSSION NUMBER 10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP132009
800 PM PDT SUN AUG 30 2009

THE STRUCTURE OF JIMENA CONTINUES TO BE CHARACTERIZED BY A SMALL EYE
EMBEDDED WITHIN A SYMMETRIC CENTRAL DENSE OVERCAST. OUTFLOW IS
EXCELLENT IN ALL QUADRANTS...AND TOPS WITHIN THE CDO HAVE CONTINUED
TO COOL. DVORAK CI-NUMBERS WERE 6.5 FROM TAFB AND 6.0 FROM SAB AT
0000 UTC...AND OBJECTIVE DVORAK CI-NUMBERS HAVE BEEN NEAR 6.5 FOR
SEVERAL HOURS. BASED ON THE INCREASING TREND IN THE SATELLITE
ESTIMATES...THE INITIAL INTENSITY IS RAISED TO 125 KT. CONTINUED
STRENGTHENING IS POSSIBLE OVER THE NEXT 24 HOURS...AS JIMENA WILL
BE IN AN IDEAL ENVIRONMENT FOR INTENSIFICATION. HOWEVER...IF AN
EYEWALL REPLACEMENT CYCLE OCCURS IT WOULD LIKELY HALT ANY
INTENSIFICATION...AT LEAST TEMPORARILY. GIVEN THE LIMITED
PREDICTABILITY OF THESE INNER-CORE CHANGES...THE OFFICIAL FORECAST
SHOWS A SLIGHT INCREASE IN INTENSITY IN THE SHORT-TERM. AROUND 48
HOURS...INCREASING WESTERLY VERTICAL WIND SHEAR AND INTERACTION
WITH LAND SHOULD CAUSE JIMENA TO WEAKEN. THE UNCERTAINTY IN THE
TRACK...AND HOW MUCH THE CYCLONE INTERACTS WITH LAND...INTRODUCES
ADDITIONAL UNCERTAINTY INTO THE INTENSITY FORECAST LATER IN THE
PERIOD.

JIMENA HAS CONTINUED TO EXHIBIT TROCHOIDAL WOBBLES FOR THE PAST FEW
HOURS. THE SMOOTHED INITIAL MOTION ESTIMATE IS 305/06...A LITTLE TO
THE RIGHT OF THE PREVIOUS ADVISORY. THE INTERACTION BETWEEN JIMENA
AND A MID- TO UPPER-LEVEL LOW CENTERED NEAR 24N 112W WILL BE
CRITICAL TO THE EVENTUAL TRACK OF THE HURRICANE. THE MID- TO
UPPER-LEVEL LOW WILL MOVE SLOWLY WESTWARD THROUGH THE FORECAST
PERIOD...AND THE GFS...NOGAPS...GFDL...GFDN...AND HWRF SUGGEST THAT
IT WILL REMAIN STRONG ENOUGH TO PULL JIMENA NORTHWARD TOWARD THE
BAJA CALIFORNIA PENINSULA. ANOTHER GROUP OF MODELS...INCLUDING THE
ECMWF...UKMET...AND CANADIAN WEAKEN THE MID- TO UPPER-LEVEL LOW AND
TURN JIMENA TOWARD THE WEST AS THE SUBTROPICAL RIDGE BUILDS NORTH
OF THE CYCLONE. THE HIGHER-RESOLUTION 1800 UTC GFS PARALLEL
ENSEMBLE MEAN SUPPORTS THE MORE EASTWARD TRACK SCENARIO...WHILE THE
1200 UTC ECMWF ENSEMBLE MEAN SHOWS A MORE WESTERLY TRACK.
HOWEVER...THERE IS LARGE SPREAD IN THE SEA-LEVEL PRESSURE FIELD
NORTH OF THE ECMWF ENSEMBLE MEAN POSITION...SUGGESTING THAT A
SIGNIFICANT NUMBER OF THE MEMBERS HAVE A TRACK CLOSER TO BAJA. THE
MULTI-MODEL TRACK CONSENSUS CONTINUES TO FAVOR THE MORE EASTWARD
SCENARIO...AND SO DOES THE OFFICIAL FORECAST...WHICH HAS BEEN
SHIFTED SLIGHTLY TO THE EAST FOR THIS PACKAGE.

BASED ON THE OFFICIAL FORECAST...THE ISSUANCE OF A HURRICANE WATCH
IS REQUIRED FOR THE SOUTHERN PORTION OF THE BAJA CALIFORNIA
PENINSULA AT THIS TIME. JIMENA IS EXPECTED TO BE A VERY DANGEROUS
HURRICANE NEAR THE SOUTHERN BAJA PENINSULA IN 36 TO 48 HOURS. THE
WIND SPEED PROBABILITY PRODUCT INDICATES THAT THERE IS CURRENTLY A
20 TO 30 PERCENT CHANCE OF HURRICANE-FORCE WINDS OCCURRING OVER THE
BAJA PENINSULA SOUTH OF A LINE FROM LORETO TO PUERTO SAN ANDRESITO.

INTERESTS IN WESTERN MAINLAND MEXICO AND ELSEWHERE IN CENTRAL AND
SOUTHERN BAJA CALIFORNIA SHOULD CONTINUE TO MONITOR THE PROGRESS OF
JIMENA. ADDITIONAL WATCHES MAY BE REQUIRED FOR PORTIONS OF THESE
AREAS TONIGHT OR MONDAY.

FORECAST POSITIONS AND MAX WINDS

INITIAL 31/0300Z 17.0N 107.2W 125 KT
12HR VT 31/1200Z 17.8N 108.0W 130 KT
24HR VT 01/0000Z 19.2N 109.1W 130 KT
36HR VT 01/1200Z 21.3N 110.2W 125 KT
48HR VT 02/0000Z 23.4N 111.0W 120 KT
72HR VT 03/0000Z 27.0N 112.5W 65 KT...INLAND
96HR VT 04/0000Z 28.6N 113.5W 40 KT...INLAND
120HR VT 05/0000Z 29.0N 115.0W 25 KT
Member Since: Posts: Comments:
Quoting Relix:
Wow 94L moving practically due North at this point. So long 94L? The Antilles says: Go away.

Do not base the movement based solely on the satellite use the numbers to help.
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Quoting FLWeatherFreak91:
The ULL will shear the invest for sure, but it won't pull it in all the way due to the anticyclone over the invest. It acts like a little "bubble" keeping it from incorporating with the ULL
Thanks, How long will the anticyclone act as a bubble? Great interpertation by the way, to help us internet students.
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Quoting Patrap:


Well,,without a sidebar needed..Thats what its doing..

Kinda Like How dem ULL's spin down,..and turn tropical ,say..Like Claudette did.
Things some times are what they are in reality


Interesting debate no less, regardless of the outcome. If it heads off to the N that would solve a lot of angst for many.
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Quoting Patrap:
StormW is in His blog..they havent handcuffed the Man and sent him to the Big House...

Oh I know....just nice to have his input in here
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2827. Patrap
All Channels here show the Motion thru time..

Atlantic 3 Hour Loops in 4 Channels

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Quoting hurricane23:


Just posted a link to that a few posts back. TCVN is all over the place.It will interesting to see what transpires this evening with convective blow ups now trying to concentrate around 14n.


Adrian...another voice of reason and reliability.
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Come on Admin, I know you are smarter than that. Use some logic.... I know there have been worse things. A lot of people come here to read StromW posts. Am I wrong WU bloggers??
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Quoting Patrap:
StormW is in His blog..they havent handcuffed the Man and sent him to the Big House...
Let's all send him a file in a belated birthday cake!
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2823. Patrap
Quoting kmanislander:


The WV loop is showing what is going on high in the atmosphere. I would not use it to try and determine where the surface low is.


Well,,without a sidebar needed..Thats what its doing..

Kinda Like How dem ULL's spin down,..and turn tropical ,say..Like Claudette did.
Things some times are what they are in reality
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Its a large system and has the potential to be a powerhouse in a few days towards the end of the week
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i dont get it NRAamy gets a 95hr ban for inappropriate images. why StormW gets a 24hr ban for inappropriate images.
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2820. amd
Jimena is an absolute monster, winds are now officially 145 mph, gusts to 180 mph.
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2819. Relix
Wow 94L moving practically due North at this point. So long 94L? The Antilles says: Go away.
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Quoting stormsurge39:
If 94L keeps going N, isnt it going to be ripped apart by that ULL to the N?
The ULL will shear the invest for sure, but it won't pull it in all the way due to the anticyclone over the invest. It acts like a little "bubble" keeping it from incorporating with the ULL
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Quoting cchsweatherman:


If you go back to all my posts with images, I site my sources or give credit to the providers. Some images have the company or website's logo, so no sourcing or crediting is needed.
Yep.. You do a great job of it. And I agree about images that have their credits as part of the image. I do not worry about NHC, NOAA etc either. And most images gotten off the web are probably fairly safe.

Many here are not as careful. Using a mascot of a major corporation is tricky. The Gecko may not like to be posted here on the blog and after all, we do not want the Gecko to come down on us with a law suit.

Rule of Thumb
- If the image is being used in an advertising campaign, or in a way that makes the owner money - think twice before posting.
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Quoting Patrap:
Its not smoke and mirrors or rocket science..the LLC has tightened and the whole system became more symmetrical,..

That and the ULL getting a lil ahead of 94L has Lifted the whole envelope a few degrees N the Last 6 Hours



The WV loop is showing what is going on high in the atmosphere. I would not use it to try and determine where the surface low is.
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Quoting kmanislander:


Welcome back. The same debate that was happening when you left is still going on LOL.

Nothing missed.
I noticed. Some things never change. Saw the language thing going on earlier too.
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Listen to KmanIslander, like I said this afternoon 94L has defied all models, Carribbean storm possible, Cuba to Florida watch out.
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Quoting GetReal:



Dynamic models now coming west???


Just posted a link to that a few posts back. TCVN is all over the place.It will interesting to see what transpires this evening with convective blow ups now trying to concentrate around 14n.
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2811. Patrap
StormW is in His blog..they havent handcuffed the Man and sent him to the Big House...
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If 94L keeps going N, isnt it going to be ripped apart by that ULL to the N?
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why did they ban storm?
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Quoting mikatnight:


What? WHAT? They banned Storm!!!??? No way...

Way. And I hope they retract it - we'll need him.
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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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