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 KBH:
thanks nrti, that's the data I was looking for, it's a lot but worth reviewing. Now considering I am an amatuer at reading storm data, what are the 10 most important criteria that determine direction and intensity of a storm system?


I don't know the answer to that question. The models assimalate a lot of data. Here is the data summary for the 12Z GFS.
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Quoting RitaEvac:


Maybe you should be


huh? what are you thinking?.....
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I see this 94L becomming a Tropical Storm, going over Puerto Rico, start affecting the SE Bahamas and then the low will either pick the storm up and move it out to sea or bypass it causing high pressure to push it back west and then South Florida will be in for a direct hit from a category 3 or 4 Hurricane by next weekend.
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Quoting txalwaysprepared:
Not worried about Tx. Worried about where it does hit. Just don't have a good feeling about it.
me either im in fl so i havent had a good feeling about it all week.
Quoting txalwaysprepared:
Not worried about Tx. Worried about where it does hit. Just don't have a good feeling about it.


Maybe you should be
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Quoting RitaEvac:


Systems in June that dont form now before entering the Carribbean form in western Carribbean, its August/September, it'll form when it wants at this point in the season...
Ok got it thank you ....
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Good spot Brazocane (#1439).
He copied ED word for word, down to the misspelling of "aggressive."

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1450. centex
GOM is just watch for now, something could happen.
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Quoting chucky7777:
care to enlighten me? thanks....


Systems in June that dont form now before entering the Carribbean form in western Carribbean, its August/September, it'll form when it wants at this point in the season...
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Not worried about Tx. Worried about where it does hit. Just don't have a good feeling about it.
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1447. JLPR
Quoting farhaonhebrew:
wath we can expect here on Puerto Rico?


im not actually sure =\
once the system becomes a TD we will have a better idea of where it is going for now you can have a look at this:
Member Since: September 4, 2007 Posts: 36 Comments: 5223
What amazes me is that something as disorganized as Danny gets classified yet 94L, which looks pretty decent in my book does not.
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1445. Grothar
Quoting Funkadelic:


I have been saying it for days, A nw track but then the high will build back in and force 94L west. It's all about timing right now. Bermuda should watch this storm too.


You think the GFS is really a little too far south? Wonder what they see that could force it so deeply?
Member Since: July 17, 2009 Posts: 71 Comments: 27210
Looks like that system coming off Africa is holding it's own
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Quoting Grothar:


He has posed an interesting question. How would one go about finding what model has performed the better of the others. I for one would really like to know, as I am sure others would. Your shift observation is quite true.


See posts #1365, 1378
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Models last week were showing a moisture surge into TX, but isnt supposed to come in till next weekend, not sure what this activity is right now out there....
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Quoting stormpetrol:
Link
Look at this visible loop of 94L COC becoming better defined all the time COC at 12.1N/47.9W.

Yes, it appears 94L is making best use of its conditions now.
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Quoting RitaEvac:



Ehhhhhh....Wrong....Try Again
care to enlighten me? thanks....
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Quoting WeatherStudent:
Here's my brief afternoon update on 94L, y'all. Enjoy!


Generally I've made a good observation, however, note that the main ball of convection is displaced to the west of the tropical low center under the influence of strong east to east northeast winds. At 28/12Z, NHC estimated the ill-defined center location at 10.5N 36.0W but other small swirls are also evident in the visible satellite imagery. My guesstimate at 13Z would be 10.5N 37.2W with a general motion just south of due west (260 degrees). With uncertainty on the initialization point, most (if not all) of the 00Z and 06Z model runs have already been too far to the north on their 6 and/or 12 hour forecast points. This 'bouncing around' with the models will settle down as the system becomes better defined and a consistent centerpoint becomes better established. Until this happens though (and it may take a couple of days), any aggresive northward trend by the models will remain suspect and a generally westward motion is more likely. Its also worth noting that the central pressure has increased in the past 24 hours from 1009MB to 1011MB, so development of this system is likely to be slow until the convection aligns better with the center of the low.

More to come tonight, thanks.



Plagarism

Link
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1438. JLPR
Quoting WeatherStudent:
Here's my brief afternoon update on 94L, y'all. Enjoy!


Generally I've made a good observation, however, note that the main ball of convection is displaced to the west of the tropical low center under the influence of strong east to east northeast winds. At 28/12Z, NHC estimated the ill-defined center location at 10.5N 36.0W but other small swirls are also evident in the visible satellite imagery. My guesstimate at 13Z would be 10.5N 37.2W with a general motion just south of due west (260 degrees). With uncertainty on the initialization point, most (if not all) of the 00Z and 06Z model runs have already been too far to the north on their 6 and/or 12 hour forecast points. This 'bouncing around' with the models will settle down as the system becomes better defined and a consistent centerpoint becomes better established. Until this happens though (and it may take a couple of days), any aggresive northward trend by the models will remain suspect and a generally westward motion is more likely. Its also worth noting that the central pressure has increased in the past 24 hours from 1009MB to 1011MB, so development of this system is likely to be slow until the convection aligns better with the center of the low.

More to come tonight, thanks.


thats from yesterday... right?
its at 47W lol
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Quoting txalwaysprepared:
This one makes my stomach turn. Don't know
why.


Same here. I have been addicted to this site and 94L. Turn east now LOL
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1436. java162
it apears that invest 94l is poised to become a tropical depression early tomorrow morning. the circulation appears to be tightening up and you can realy see the banding features becominig more pronounced. all this needs is a burst of more heavy convection directly over the center tonight and it will be well on its way to becominig Erika
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Quoting WeatherStudent:


Thank you for that, I wasn't aware of that.

sure. No problem.
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Quoting WeatherStudent:
Here's my brief afternoon update on 94L, y'all. Enjoy!


Generally I've made a good observation, however, note that the main ball of convection is displaced to the west of the tropical low center under the influence of strong east to east northeast winds. At 28/12Z, NHC estimated the ill-defined center location at 10.5N 36.0W but other small swirls are also evident in the visible satellite imagery. My guesstimate at 13Z would be 10.5N 37.2W with a general motion just south of due west (260 degrees). With uncertainty on the initialization point, most (if not all) of the 00Z and 06Z model runs have already been too far to the north on their 6 and/or 12 hour forecast points. This 'bouncing around' with the models will settle down as the system becomes better defined and a consistent centerpoint becomes better established. Until this happens though (and it may take a couple of days), any aggresive northward trend by the models will remain suspect and a generally westward motion is more likely. Its also worth noting that the central pressure has increased in the past 24 hours from 1009MB to 1011MB, so development of this system is likely to be slow until the convection aligns better with the center of the low.

More to come tonight, thanks.


Thanks, WS.
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Quoting txalwaysprepared:
This one makes my stomach turn. Don't know why.
i wouldnt worry bout tx on this one. whatever that explosion off of tx is gonna block it.
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1431. centex
Crow is best when slow cooked so we should put it on fire "indirect heat" now, it will taste better.
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Link
Look at this visible loop of 94L COC becoming better defined all the time COC at 12.1N/47.9W.
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I think someone earlier said something about an area in the Carribean and something in the GOM that may be of interest or looks interesting...Anything on that?
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Quoting chucky7777:
thanks i suspected that was what it meant but i was not certain thanks....



Ehhhhhh....Wrong....Try Again
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1426. Grothar
TO: CHIKLIT
re: your map
That is funny!! But good advice. True, a picture says a thousand words!!
Member Since: July 17, 2009 Posts: 71 Comments: 27210
Quoting KBH:

now we're onto something. Each model utilises the same raw data each year to make predictions (I guess sea temp, shear, SAL, TS activity etc) so the reason why each model is inconsistent is because they use the same criteria, regardless to storm cycle..el nino, la nina, etc
Does any model change the raw data based on the particular storm cycle?



Models assimalate the raw data in different ways, but also the models have different resolutions and different methods for solving the equations that make up the model.

Model Summary
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This one makes my stomach turn. Don't know why.
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Quoting mobilegirl81:
I'll bet 20 crow beaks it does not turn into a fish LOL
get ya plate ready haha thats a good buffet but i dont like crow
Quoting WeatherStudent:
Here's my brief afternoon update on 94L, y'all. Enjoy!


Generally I've made a good observation, however, note that the main ball of convection is displaced to the west of the tropical low center under the influence of strong east to east northeast winds. At 28/12Z, NHC estimated the ill-defined center location at 10.5N 36.0W but other small swirls are also evident in the visible satellite imagery. My guesstimate at 13Z would be 10.5N 37.2W with a general motion just south of due west (260 degrees). With uncertainty on the initialization point, most (if not all) of the 00Z and 06Z model runs have already been too far to the north on their 6 and/or 12 hour forecast points. This 'bouncing around' with the models will settle down as the system becomes better defined and a consistent centerpoint becomes better established. Until this happens though (and it may take a couple of days), any aggresive northward trend by the models will remain suspect and a generally westward motion is more likely. Its also worth noting that the central pressure has increased in the past 24 hours from 1009MB to 1011MB, so development of this system is likely to be slow until the convection aligns better with the center of the low.

More to come tonight, thanks.

The pressure has dropped and is now 1007mb.
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I'll bet 20 crow beaks it does not turn into a fish LOL
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1419. Grothar
Quoting nrtiwlnvragn:


Some of the consensus models perform slightly better than NHC official forecast. It may be due to a "response lag" with official forecasts, the NHC does not in general make dramatic shifts to their forecast cycle to cycle, but does it in a gradual way.


He has posed an interesting question. How would one go about finding what model has performed the better of the others. I for one would really like to know, as I am sure others would. Your shift observation is quite true.
Member Since: July 17, 2009 Posts: 71 Comments: 27210
wath we can expect here on Puerto Rico?
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1417. centex
It's a potato, meaning weak. Looking like another 36 or 48 hrs to organize. May go back to yellow tonight. Feeling more confident going into carribean. Not giving any forecast once it gets there.
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Quoting Hhunter:


purple spot i see possible swirl...


Weather has already kicked up today IN the GOM.
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Quoting kuppenskup:
What are the chances of 94L(Future Hurricane) hitting the South florida area? Anyone?

if it takes the frances track than a high chance but if not than i would say into the hurricane graveyard.
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What are the chances of 94L(Future Hurricane) hitting the South florida area? Anyone?
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1412. KBH
thanks nrti, that's the data I was looking for, it's a lot but worth reviewing. Now considering I am an amatuer at reading storm data, what are the 10 most important criteria that determine direction and intensity of a storm system?
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Quoting GeorgefromLosCabos:
I am in the path of Jimena, it's really odd that the Local people doesn't know about the hurricane!

Hang Tight , looks you could be in for one hell of a ride, I know storms don't strike there often, but once you're in the line of fire you need to be prepared no matter the statistics, keep safe.
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Quoting Grothar:


Not sure, but I believe the NHC models has outperformed all models with a higher degree of accuracy. I do not want to quote incorrectly, but I believe it may have been in one of Dr. Master's blogs. Like I said, I do not want to misquote, but I am sure I shall be corrected if I am wrong.


Some of the consensus models perform slightly better than NHC official forecast. It may be due to a "response lag" with official forecasts, the NHC does not in general make dramatic shifts to their forecast cycle to cycle, but does it in a gradual way.
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1408. Grothar
Quoting flsky:


My son sent me an email this morning saying he and his girlfriend are going to Cabo tomorrow. They know there is a hurricane on the way, but I don't think they know how strong it's going to be. I've been keeping them updated from info I get here on WU. My guess is that their flight is going to be canceled. Personally, I hope they delay the trip for a while.


If I were he, I would watch quite closely. I am sure you know the location of Cabo San Lucas. While there are some indications, the system could veer away, it is just a little too close for comfort. I am sure the airlines are closely monitoring the system and will give fair warning.
Member Since: July 17, 2009 Posts: 71 Comments: 27210

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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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