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 Grothar:


I do not disagree. Could face some wind shear ahead. But they might see something we do not, eh? Can not wait for the 8AM model which comes out as 7am or the 11am which comes out at 10AM which is information which is actually from 8:28 AM. (Did I get it right, lol)


Daylight time or standard?
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Quoting IKE:


And I'm here too. I said "next" yesterday morning. And I still think it will go ENE to NE of the islands and head toward Bermuda.




...models appear to have shifted a tad north.


Question for you, you said you agree with the ECMWF on intensity do you then not agree on its track? I would think a weaker system would not get pulled as far North as HWRF is saying.
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In general, it would be very unusual for a late-August disturbance in its current position to miss the islands, at least the Leeward islands. If it was already a hurricane, an ULL in the right position could cause it to swing NW abruptly and miss the islands, but it's still only a t-low as of now.
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Quoting WRONGASUSUALTHISYEAR:
NO ONE CARES ABUT YOUR AMATEUR FORCAST NOW GO BACK TO BED


Learn to spell 'forecast' kid, then we'll see who's 'amateur'.
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Quoting nrtiwlnvragn:


well we can through out the NW models since they have not verified. also the models have now point towards the west. Doesnt seem like Bermuda will see 94L.
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Quoting tornadofan:


I'm here! I think red alert is a little overboard. Give it 24 hours and let's see how well it's doing...




I do not disagree. Could face some wind shear ahead. But they might see something we do not, eh? Can not wait for the 8AM model which comes out as 7am or the 11am which comes out at 10AM which is information which is actually from 8:28 AM. (Did I get it right, lol)
Member Since: July 17, 2009 Posts: 71 Comments: 26489
Quoting WRONGASUSUALTHISYEAR:
94L WILL BE JUST ANOTHER FISH STORM IF IT EVEN DEVELOPS OR IT WILL START TO DEVELOP THEN FALL APART


Looks like someone forgot to take their medicine.

Good Morning everyone! I'll have a forecast up soon on my blog (I've been lazy this year so far with that)
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199. IKE
Quoting tornadofan:


I'm here! I think red alert is a little overboard. Give it 24 hours and let's see how well it's doing...




And I'm here too. I said "next" yesterday morning. And I still think it will go ENE to NE of the islands and head toward Bermuda.


Quoting nrtiwlnvragn:


...models appear to have shifted a tad north.
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Quoting Weather456:
Perpestive





In addition, the Bermuda high will strengthen. This will not be another Bill.
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197. Relix
Quoting nrtiwlnvragn:


Man I am still trying to figure out why the models stick to such a dramatic NW turn >_>. I know there are troughs and all, but that hard turn!?
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why are the track models so off????
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Quoting Grothar:
Many had RIP for 94L last night and I do not see them this morning. That is OK. I am surprised to go to sleep with a little yellow circle on 94L and awake to RED. It just got us a little excited. I thank you all for these updates.


I'm here! I think red alert is a little overboard. Give it 24 hours and let's see how well it's doing...


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Perpestive



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Look at TAFB Dvorak

AL 94 200908301145 10 DVTS CI 1120N 4580W TAFB 2530 ///// DT = 2.5 BASED ON 0.4 BANDING. NLINEMET= 1.0 PAT=
AL 94 200908301145 10 DVTS CI 1190N 4610W SAB 1515 ///// DT=1.5 SCENE=CB MET=1.5 PT=1.5 FTBO=DT POS ACC=50
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So far this year the gulf coast has been protected from the cape verde and long-track Atlantic storms by the area of troughiness over Florida, but if a system were to miss the trough and pass south of it, the trough would then act to steer it into the Gulf.
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Morning everyone. Many of you may not have been on yesterday when the blog got heated and out of control. Please let us enjoy each other's comments and discuss them in a civil manner just once, especially Sunday, Please . They were correcting everyone's grammer and it got ridiculous. There were good comments this morning. I thank you all for them. Many had RIP for 94L last night and I do not see them this morning. That is OK. I am surprised to go to sleep with a little yellow circle on 94L and awake to RED. It just got us a little excited. I thank you all for these updates.
Member Since: July 17, 2009 Posts: 71 Comments: 26489
Quoting PensacolaBuoy:
Next update on Jimena should be CAT 4. It's unbelievable how much this system has expanded overnight. Pinpoint eye is impressive.


I won't be surprised if it becomes a category 5; I think it will.
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Quoting HurricaneKyle:


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.


Dude, change out your personal graphics. The blast is annoying. I could hide you, but I am actually interested in what you have to say...
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Quoting islandblow:
Thanks Relix and SLU. I stand by your view of things. People forget that our islands are so small that a cluster gets affected even if the eye does not go directly overhead. Wind apart, just heavy rain rips these steep volcanic islands apart and Barbados floods easily. Even with an unlikely shift north at this stage we are in for some bad weather


you are from dominica like i am and we dont flood!!!!!
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Next update on Jimena should be CAT 4. It's unbelievable how much this system has expanded overnight. Pinpoint eye is impressive.
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184. IKE
Quoting P451:


Very good point.
It is also why I'm not looking to guess based on what satellite imagery loops seem to hint at - but rather just go by what the discussions have to say.

I think something that can be agreed upon is that the system is more organized than it has been in the past yet is quite lopsided and the low center is on the eastern side of all that convection - and until the system becomes more symmetrical/organized you wouldn't look for any rapid intensification.


You're right. The main blob of convection is west of the stated center coordinates of 94L.
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Quoting P451:


Well, that's just ridiculous on their part, if that is indeed the case. What's the point if they're going to be off by a few hours each time? If they're writing a discussion based on 6Z data then they need to say as much. Since they don't then it's still open to speculation IMO.


they do state it though. it's there for everyone to read.
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182. SLU
Quoting islandblow:
Thanks Relix and SLU. I stand by your view of things. People forget that our islands are so small that a cluster gets affected even if the eye does not go directly overhead. Wind apart, just heavy rain rips these steep volcanic islands apart and Barbados floods easily. Even with an unlikely shift north at this stage we are in for some bad weather


yes there may be some kind of impact somewhere
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From TWD

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC.
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Quoting IKE:
06 GMT 08/30/09 11.2N 45.1W 25 1008 Invest
12 GMT 08/30/09 11.8N 46.3W 25 1007 Invest


It's moved .6N and 1.2W. It's moving true WNW. If it stays on that path it would be at....

17.8N and 58.3W, in the future. Looking at a map of those coordinates, that would put it ENE of the islands.

that's if those coordinates are accurate.

without a well defined center it's just a best guess as of now.
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179. SLU
30/1145 UTC 11.9N 46.1W T1.5/1.5 94L -- Atlantic

Not too far away from being a TD.
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Blog Update
Reflector site for those at work, includes Dr. Masters & Weather456, daily update.


AOI

AOI

AOI

AOI
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Thanks Relix and SLU. I stand by your view of things. People forget that our islands are so small that a cluster gets affected even if the eye does not go directly overhead. Wind apart, just heavy rain rips these steep volcanic islands apart and Barbados floods easily. Even with an unlikely shift north at this stage we are in for some bad weather
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176. Relix
Quoting IKE:
06 GMT 08/30/09 11.2N 45.1W 25 1008 Invest
12 GMT 08/30/09 11.8N 46.3W 25 1007 Invest


It's moved .6N and 1.2W. It's moving true WNW. If it stays on that path it would be at....

17.8N and 58.3W, in the future. Looking at a map of those coordinates, that would put it ENE of the islands.


Remember that they don't exactly know where the center is and that it could relocate. Any southern change or a big west wobble would change things for people in the Antilles. Or it could move NW before expected. All this is possible. Meanwhile I'll eat my Pop Tart while I watch WU =P
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Quoting HurricaneKyle:


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.

it's because the info is a little old when they put it out.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1015 UTC.

so the 8am outlook is based on 2:00am surface maps and 6:15am satellite imagery
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Quoting WRONGASUSUALTHISYEAR:
YOUR 100% RIGHT AND THEY ARE ALL WRONG ITS GOING DUE WEST NOT EVEN CLOSE TO ANYTHING ELSE

TAKE A BREAK IT'LL GO NORTHWEST

and stop posting in all caps.. there is no reason to do so
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Quoting HurricaneKyle:
I looked at the models, all of them have 94L going NW or a very WNW direction right now. 94L is going straight west.


we always go through this, I myself have, we say whats wrong with the NHC can't they see what I see... well most of the time the models are correct and you say to yourself ok thats why they get paid (NHC).... I will trust the models and believe it'll start moving NW... although......hmmmmm
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Quoting tikikopamsxm:
hello weather456
I'm taking the plane to france today and i want to know what is going to be the strengh of 94L when it passes next to Sint Maarten. My wife and baby are staying a week alone.
Thank you for your answer.


at most a moderate TS. I'm seeing more of gradual development rather than rapid development like Bill when it was north of us. 94L could pass to the Northeast of the island but Saint Maarten is closer to the Atlantic. so if it does get close enough, some squally weather and gusty winds, but nothing i would say full blown hurricane...

:)
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At 12Z NHC has 94L moving at 285 degrees, 15 mph.
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169. IKE
06 GMT 08/30/09 11.2N 45.1W 25 1008 Invest
12 GMT 08/30/09 11.8N 46.3W 25 1007 Invest


It's moved .6N and 1.2W. It's moving true WNW. If it stays on that path it would be at....

17.8N and 58.3W, in the future. Looking at a map of those coordinates, that would put it ENE of the islands.
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167. SLU
Quoting P451:


Discussion states the Low Center at 8am is at 44W.

So either looks can be deceiving which they can or the discussion is and has been incorrect each and every release.

I'm not looking to argue it but I'm just going by what the discussion says.

*shrugs*




Yeah I know...

The 8am discussion uses the 06Z information I believe so it's a little behind schedule.
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Quoting futuremet:
Well, I guess we will finally stop hearing "RIP 94l now".


FM - not yet. 94L looks to have shearing problems still. DMIN was good to it, but lets see how it does the next 24 hours. I could see upping it to orange this morning, but red alert seems overboard.

EDIT - oops meant to say DMAX was good to it. Heh.
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94L 12Z SHIPS

Prob of RI for 25 kt RI threshold= 41% is 3.3 times the sample mean(12.3%)
Prob of RI for 30 kt RI threshold= 24% is 3.0 times the sample mean( 8.0%)
Prob of RI for 35 kt RI threshold= 16% is 3.3 times the sample mean( 4.8%)
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hello weather456
I'm taking the plane to france today and i want to know what is going to be the strengh of 94L when it passes next to Sint Maarten. My wife and baby are staying a week alone.
Thank you for your answer.
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Quoting Grothar:


Hey Mikatnight, Grothar here. Didn't even have coffee and didn't like update either, I mean great update poor scenario. Morning Early lurker.


where do you live?
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161. SLU
Quoting Weather456:


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.



No it's no Bill. If it crosses 50W south of 13N then climatology suggests that it may strike the Lesser Antilles. About 90 - 95% or so of all systems which pass through that location impact the Caribbean.
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Quoting Weather456:


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.


Very true. I wish these products were posted with the time they were actually produced instead of a standard time. If the TWD comes out at 7AM instead of 8AM, and it was time-stamped that way, you could more easily understand their comments. For instance, if there is a "big blow-up of convection" in a system over the last three satellite frames,and the NHC didn't mention it, you could chalk it up to an early issuance of the product. I'd really rather them hold off on these products until the standard time and update it as necessary before they post it.
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Quoting mikatnight:


Mornin' 456. Just read your update. Thanks, but it didn't make me feel any better...


Hey Mikatnight, Grothar here. Didn't even have coffee and didn't like update either, I mean great update poor scenario. Morning Early lurker.
Member Since: July 17, 2009 Posts: 71 Comments: 26489

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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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