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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2458. Patrap
00 Z Statistical Models


Member Since: July 3, 2005 Posts: 428 Comments: 129903
2457. mazgreg
Quoting cchsweatherman:


I don't believe I have ever seen a tropical cyclone affecting such an expanse of atmosphere before as Jimena is currently doing. Its outflow extends to the Central GOM for crying out loud. This is probably one of the most impressive tropical cyclones I have ever seen in my life time.

We have a high, solid, dark cloud cover here in Mazatlan no wind and no surf to speak of yet. I think the center is more than 400 miles away to the south
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Quoting StormW:
Evening 456!


Evening SW, hope you enjoyed your Bday.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Believe it or not, the interpolated HWRF is not the most intense forecast. And few of them see the end of 94's potential.


Wrong url, fixed.
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2452. Patrap
Member Since: July 3, 2005 Posts: 428 Comments: 129903
2451. ssmate
Thanks for your input tonight Drak.
Member Since: July 17, 2008 Posts: 0 Comments: 347
Quoting canesrule1:
00z models have shifted south, by several hundred miles.


can you give the link. Thanks.
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Quoting AllStar17:
Safe to say models have no idea where this system will ultimately end up with the exception of in the Atlantic basin and somewhere near the Leewards.


Thats why I love 94L. You would die if you always rely on models. This is one system where the noggin is put to test.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
2447. JLPR
when 94L gets close to the islands
that is if it does
it would then hit much warmer waters
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Thanx Caicos!
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Dive to the SW at the end of the forecast run. A little like Ike...was getting pulled NW (by Hanna) but high pressure comes back.
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As of NHC 8 p.m. Discussion, Jimena's track is still not the one we want.
Link
THERE HAVE BEEN SOME TROCHOIDAL WOBBLES...TYPICAL OF THE MOVEMENT OF INTENSE HURRICANES...BUT THE SMOOTHED INITIAL MOTION ESTIMATE IS ABOUT 295/07. THE FUTURE TRACK OF JIMENA SEEMS TO DEPEND LARGELY UPON THE EVOLUTION OF TWO MAIN FACTORS...A MID- TO UPPER-LEVEL LOW LOCATED NEAR THE SOUTHERN BAJA CALIFORNIA PENINSULA AND A MID-LEVEL RIDGE OVER THE SOUTHWESTERN U.S. AND NORTHWESTERN MEXICO. IF THE LOW SHIFTS WESTWARD AND WEAKENS...IT WOULD ALLOW THE RIDGE TO BUILD WESTWARD AND COULD CAUSE THE TRACK TO VEER WESTWARD AWAY FROM BAJA.
THAT APPEARS TO BE THE SCENARIO DEPICTED BY THE U.K. MET. OFFICE AND ECMWF GLOBAL MODELS. HOWEVER...THOSE MODELS ARE THE WESTERN OUTLIERS OF THE DYNAMICAL TRACK GUIDANCE. OTHER GUIDANCE SUCH AS THE GFS...THE HWRF...AND THE GFDL INDICATE THAT THE MID-TO UPPER-LEVEL LOW WILL CONTINUE TO INFLUENCE THE MOVEMENT OF THE HURRICANE...SO THAT JIMENA WILL CONTINUE TO TURN TOWARD THE RIGHT...AND MOVE NEAR OR OVER BAJA. THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ONE AND IS CLOSE TO THE MIDDLE OF THE MODEL TRACKS.

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2443. JamesSA
Quoting Patrap:
00 Z Dynamical Model Suite


It is developing a better structure now and they are starting to look a little more realistic.
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2442. Relix
Quoting Weather456:



tell me about it.


That west movement should be the high then. Oh w/e really I am tired it keeps making fun of me XD!
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2441. JRRP
ok..
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2440. Drakoen
I'm out for the night.
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Quoting Weather456:



tell me about it.
yup
Safe to say models have no idea where this system will ultimately end up with the exception of in the Atlantic basin and somewhere near the Leewards.
Member Since: June 29, 2009 Posts: 13 Comments: 5315
Quoting canesrule1:
00z models have shifted south, by several hundred miles.



tell me about it.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
2435. JLPR
Quoting Patrap:
00 Z Dynamical Model Suite



well... thats no good
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2433. Patrap
Member Since: July 3, 2005 Posts: 428 Comments: 129903
00z models have shifted south, by several hundred miles.
2430. Relix
Seems like 94 could miss PR. Guess I should keep the crow still frozen =P
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atomo aggie, Jimena would look like its going a little cross eyed in the loop.
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2427. Patrap
00 Z Dynamical Model Suite

Member Since: July 3, 2005 Posts: 428 Comments: 129903
Quoting StormW:



"You called...mate"?




haha love it, good evening all
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting BahaHurican:
That is downright eerie.....

Hope somebody is archiving these loops....

McIDAS navigation errors are fun...trust me.
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LMAO! Never laugh so much at models

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Patrap:
18 Z Statistical Model suite




None of those tracks are good.....especially if this system was to strengthen into a formidable cyclone.
Member Since: June 29, 2009 Posts: 13 Comments: 5315
I understand that the current convection in the GOM is from the tail end of the front across the eastern half of the US. Would this "piece" need to detach itself and become it own entity to form something tropical? What would be the signs over the next few days to look for to know? Please don't burn me I am just trying to learn...
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Quoting Patrap:
94L 18 Z Dynamic Model Suite



Uhh... err.. uhm.. hard to judge track with that kind of run.
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2419. Patrap
00 Z Statistical Models


Member Since: July 3, 2005 Posts: 428 Comments: 129903
Quoting nrtiwlnvragn:
LOL


Florida trajectory, huh.
Quoting nrtiwlnvragn:
LOL




Kind of reminds me of the cartoon from xkcd.com
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2415. GatorWX
Wow, Jimena looks fantastic, so compact! Haven't seen the storm all day before now, just got home from work. Terrific looking little storm though. Look out Mexico! Good thing it's so small, should keep the path of destruction pretty narrow. Looks like a Charley size storm.
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Quoting atmoaggie:

Hmm. I know where you got that. Unless you are MW, himself.


Not!
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Thanks weather456
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2411. Patrap
18 Z Statistical Model suite


Member Since: July 3, 2005 Posts: 428 Comments: 129903
2410. JLPR
check it out
winds from the north and winds from the south

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Quoting StormJunkie:


Okie, right or wrong, I think it is because it is lest often that the pacific storms impact the US or Mexico. Fewer people from those areas are on the blogs; therefore fewer posts concerning the very impressive Jimena.

I think SJ is right abt the larger # of ATL basin bloggers being interested in ATL storms. But I also think there is a lot more to debate abt a storm system at 94L's stage of development. When Bill's fate was considered assured, for example, blogging decreased here.
Member Since: October 25, 2005 Posts: 19 Comments: 22736
2408. Drakoen
Early 00z runs have shifted to the north
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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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