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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2758. GatorWX
Just saw the ir floater of 94, haven't really been paying too much attention, but it is looking good now. I know the llc is nearly devoid of convection, but this is changing.

To those who have commented on the convection firing, it is indeed. Right near the center too. This should not only help it become a TD, but will also make the allusion of its northern movement nonexistent. If it keeps up, could be a td in the late morning, early afternoon.
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2756. Dakster
Apparently, the blog masters review posted pictures and not necessarily written content or the wishes of the other bloggers. (I am sure that a lot of people hit the ole '-' on a particular persons post)

Back to the weather.

It looks like in the last frame 94L is going north - or is that an illusion since it is consolidating.
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Quoting kmanislander:
The 850 mb vorticity with 94L is all the way up near 14 to 16N. That is what is predominant on the sat images and loops.

The surface low is closer to 11 and 12N.

It is tilted from the SW to the NE
this also makes it a weak system, right?
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2754. Bonz
"JFV...some of the models are bringing 94 right to south Florida. Are you prepared?"

Hope those are the less accurate models. Not in the mood for a Fort Lauderdale 'cane.
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Quoting kmanislander:
The 850 mb vorticity with 94L is all the way up near 14 to 16N. That is what is predominant on the sat images and loops.

The surface low is closer to 11 and 12N.

It is tilted from the SW to the NE
Now that makes sense, thanks.
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Quoting winter123:
if you ask me, i think jimena is approaching world records, its just exploding and is like 500 mile sphere of inffluence by now.


Jimena is causing black mares' tails over Central Texas...... never seen that before. This is the first year I can remember mares' tails not accurately forecasting rain within 24 hours.
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2751. jipmg
Quoting GeoffreyWPB:
JFV...some of the models are bringing 94 right to south Florida. Are you prepared?


they are?!! LOL

anyhow, Jimena is blind, and thats all I have to say for now..oh, I almost forgot, Imagine how cold this winter will be for FLA, with cold fronts making there way into North FLA in AUGUST?
The 850 mb vorticity with 94L is all the way up near 14 to 16N. That is what is predominant on the sat images and loops.

The surface low is closer to 11 and 12N.

It is tilted from the SW to the NE
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2749. Patrap


Area forecast discussion
National Weather Service New Orleans la
807 PM CDT sun Aug 30 2009


Update...
..sounding discussion...


Dry air is present in the middle levels of the atmosphere bring the
precipitable water value down to 1.67 inches. Isolated
thunderstorms developed south of Lake Pontchartrain and brought
several inches of rain in a short period of time. A few new cells
have recently formed ahead of the front. Winds are out of the
north at the surface and out of the west above 850 mb.


&&


Previous discussion... /issued 329 PM CDT sun Aug 30 2009/


Short term...


A fast moving short wave trough combined with a weak surface
reflection will continue to bring scattered convective activity to
eastern and southern zones through tonight. As this system pulls
quickly to the northeast over the next 12 hours...a frontal
boundary currently over northern Louisiana will be forced
southward into the area tonight. However...the front is expected
to hang up along the coast for tomorrow...as another weak upper
level impulse slides through the area. Along and ahead of the
frontal boundary...ample instability will support continued
scattered convection through the daytime hours. Conditions will
finally begin to dry out tomorrow night as the front slowly pulls
southward in the wake of the second upper level impulse. The front
should finally clear the forecast area on Tuesday as it leaves the
offshore coastal waters and moves into the central Gulf of Mexico.
In the wake of the front...a very strong surge of cooler and drier
air will infiltrate the area. Looking at 1000-500mb thicknesses
shows a good 30 meter drop. This would translate into daytime
temperatures a few degrees below normal through the week as this
cooler airmass settles in. Also...with very dry air working in
throughout the atmospheric column...as indicated by precipitable water values
falling to around an inch...expect near record low temperatures
once again. Overnight lows north of I-10 should dip into the lower
60s from Tuesday to Thursday.


Long term...


Heading into the middle of the week...one feature to be noticed
is the development of a possible low along the old frontal
boundary in the central Gulf of Mexico Wednesday into Thursday.
Both the NAM and GFS depict a weak surface low forming...and then
slowly moving to the northeast toward the Florida Panhandle. Given
the time of year...there may be some potential for a weak tropical
low to take hold. However...several limiting factors will be in
play...including dry air feeding into the system and a decent
amount of shear in the region. Fortunately...the region looks to
be on the western or drier side of the system for the latter half
of the week. At most...some wrap around mositure and showers may
affect coastal Mississippi zones on Thursday.


The low should become sheared out by Friday...with the deepest
moisture pulling to the east toward the western Atlantic. As this
happens...a return to more typical Summer like conditions is
expected to take hold. Both the GFS and European model (ecmwf) show a weakening of
the strong trough dominating the eastern third of the nation by
the end of the week and into the weekend...with some weak upper
level ridging taking hold by Sunday. With this pattern
developing...no large scale forcing mecanisms are expected to
influence the region. Temperatures and moisture profiles will
return to more normal expectations...although middle-level moisture
should continue to be somewhat limited...putting a cap on some
convective activity over the weekend. Overall...expect isolated
diurnally induced convective development Friday through
Sunday...with development most likely to occur near seabreeze
boundaries or remnant outflow boundaries from previous convection.

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Quoting Patrap:


We are having some crazy lightning here in Plaquemines parish from this..
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2747. flsky
Quoting Patrap:
Geeezum,..just had Pea Sized hail for 45 secs then a wisp of 30 Plus under the wood threshold and that wicked ,Hummmmmmmmmmmmmmmmmmm...



Wonder if this track is heading toward ECFL
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The August 2009 GOES East Infrared Hurricane Sector & Alley animations are currently being uploaded to YouTube.com!!!

That's two videos from me in one day!

Enjoy!
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I am wondering if perhaps the issue was with the possibility of copyright infringement etc.

Someone else mentioned they also received a ban after posting an image.

Make sure you have permission to use an image before you post it folks!
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2743. pottery
StormW has a new blog up.
I am sure he will be able to give his insight into 94L.
But please, can we all leave the Banned thing out of the discussion for a while?
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2742. Patrap


Area forecast discussion
National Weather Service New Orleans la
807 PM CDT sun Aug 30 2009


Update...
..sounding discussion...


Dry air is present in the middle levels of the atmosphere bring the
precipitable water value down to 1.67 inches. Isolated
thunderstorms developed south of Lake Pontchartrain and brought
several inches of rain in a short period of time. A few new cells
have recently formed ahead of the front. Winds are out of the
north at the surface and out of the west above 850 mb.


&&


Previous discussion... /issued 329 PM CDT sun Aug 30 2009/


Short term...


A fast moving short wave trough combined with a weak surface
reflection will continue to bring scattered convective activity to
eastern and southern zones through tonight. As this system pulls
quickly to the northeast over the next 12 hours...a frontal
boundary currently over northern Louisiana will be forced
southward into the area tonight. However...the front is expected
to hang up along the coast for tomorrow...as another weak upper
level impulse slides through the area. Along and ahead of the
frontal boundary...ample instability will support continued
scattered convection through the daytime hours. Conditions will
finally begin to dry out tomorrow night as the front slowly pulls
southward in the wake of the second upper level impulse. The front
should finally clear the forecast area on Tuesday as it leaves the
offshore coastal waters and moves into the central Gulf of Mexico.
In the wake of the front...a very strong surge of cooler and drier
air will infiltrate the area. Looking at 1000-500mb thicknesses
shows a good 30 meter drop. This would translate into daytime
temperatures a few degrees below normal through the week as this
cooler airmass settles in. Also...with very dry air working in
throughout the atmospheric column...as indicated by precipitable water values
falling to around an inch...expect near record low temperatures
once again. Overnight lows north of I-10 should dip into the lower
60s from Tuesday to Thursday.


Long term...


Heading into the middle of the week...one feature to be noticed
is the development of a possible low along the old frontal
boundary in the central Gulf of Mexico Wednesday into Thursday.
Both the NAM and GFS depict a weak surface low forming...and then
slowly moving to the northeast toward the Florida Panhandle. Given
the time of year...there may be some potential for a weak tropical
low to take hold. However...several limiting factors will be in
play...including dry air feeding into the system and a decent
amount of shear in the region. Fortunately...the region looks to
be on the western or drier side of the system for the latter half
of the week. At most...some wrap around mositure and showers may
affect coastal Mississippi zones on Thursday.


The low should become sheared out by Friday...with the deepest
moisture pulling to the east toward the western Atlantic. As this
happens...a return to more typical Summer like conditions is
expected to take hold. Both the GFS and European model (ecmwf) show a weakening of
the strong trough dominating the eastern third of the nation by
the end of the week and into the weekend...with some weak upper
level ridging taking hold by Sunday. With this pattern
developing...no large scale forcing mecanisms are expected to
influence the region. Temperatures and moisture profiles will
return to more normal expectations...although middle-level moisture
should continue to be somewhat limited...putting a cap on some
convective activity over the weekend. Overall...expect isolated
diurnally induced convective development Friday through
Sunday...with development most likely to occur near seabreeze
boundaries or remnant outflow boundaries from previous convection.

Member Since: Posts: Comments:
JFV...some of the models are bringing 94 right to south Florida. Are you prepared?
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94L should get healthy tonight into early tomorrow, but definitely if shear can hold off and it can get into higher SSTs close to 29C tomorrow. I am going to sleep now, long day ahead. Good night everyone.
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Quoting Patrap:


Yeah I saw that Band sit over that way this afternoon


1.4inches of rain in Mobile area but I missed it due to being on the road coming back from Mc Donough GA..... It did rain all the way to Evergreen AL then sun the rest of the way....

taco :0)
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if you ask me, i think jimena is approaching world records, its just exploding and is like 500 mile sphere of inffluence by now.
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Quoting Patrap:

I love the complexity of this subject.

Well, no possibility of a nado...at least not a counterclockwise-turning one. Shear is the wrong way for that.

Wonder if the one near Corpus today was a odd-turner...

So, I guess the next question is, who reported StormW? Or did WU just happen to be watching closely?
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2735. Jerrob
Quoting Relix:
StormW ban should have waited. He's a great resource especially now, it was a pretty minor offense compared to other things here.

I agree since this afternoon all the talk was about football..!
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By eye sight 94L looks very sick!! When will it get the oppurtunity to get healthy and stay that way? Will it be W WNW NW NNW N NE NNE SW S SSW SE SSE? Just kidding! seriously when does this have a shot?
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2733. GatorWX
Quoting btwntx08:

no not at 11 pm its at the point the sun rises


It's not just at one moment, dmax is a period of time. And it is most prevalent in the times he noted. It is truly dMAX at around 0300-0400.
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Quoting Patrap:
As per Senior Chief StormW's wu -mail to me..


StormW has been Banned for 24 Hours ...
The pic was in reference to the two eyed satellite loop. It didn't bother me, and added some necessary humor to the blog. Perparing for a storm or even a possible storm is a stressful activity, and a little humor goes a long way.

This morning, personal insults were being cast about, and then this afternoon a certain blogger claimed someone elses work was his, and cast insults in Spanish to his critics afterwards.

I guess a picture is worth a thousand words?

Gulf of Mexico keeps getting more interesting. Is this all from Jimena?
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94l is the weirdest looking pre-TD i have ever seen. Oh, and the dual eye with jimena was just insane wobbling, like 15 mile wobble from west to east.

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94L is starting to pop convection. There is an anticyclone over 94L and it is moderate in strength. 94L is more than just an open wave. A broad yet strengthening low level circulation is apparent with an anticyclonic flow aloft and upper level low is moving faster to the WSW.
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Quoting KEHCharleston:
So the question is not when will it turn, but when will it intensify!


IMO 94L is just a tropical wave that has lost a lot of its punch today. The stronger it becomes the more it is likely to turn. The opposite is also true.
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Recon for tomorrow..
000
NOUS42 KNHC 301630
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NTIONAL HURRICANE CENTER, MIAMI, FL.
1230 PM EDT SUN 30 AUGUST 2009
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 31/1100Z AUGUST TO 01/1100Z SEPTEMBER 2009
TCPOD NUMBER.....09-094

I. ATLANTIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY:
A. POSSIBLE TASKING NEAR 16.0N 54.0W FOR 01/1800Z.
B. BEGIN 6-HRLY FIXES NEAR 17.0N 56.0W AT 02/0600Z
IF SYSTEM DEVELOPS.

II. PACIFIC REQUIREMENTS
1. HURRICANE JIMENA
FLIGHT ONE -- TEAL 70
A. 31/1800Z
B. AFXXX 0113E JIMENA
C. 31/1315Z
D. 19.0N 108.8W
E. 31/1700Z TO 31/2100Z
F. SFC TO 10,000 FT

2. SUCCEEDING DAY OUTLOOK: JIMENA FIX MISSION FOR
01/1800Z NEAR 22.5N 110.8W.
SEF


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Quoting Funkadelic:

What!! Stormw gets banned for that, but not weatherstudent for plagirism?


That better not be true, as much as Storm contributes to this blog and the great information he passes along, he should be allowed as pass. That is BS if true WU admin.
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2724. flsky
Quoting FloridaTigers:


Agreed, yet plagiarism by guys like jasoniscool and WeatherStudent goes unpenalized. Some sort of double standard.

I agree. It's very strange. They both broke the rules but only one got banned.
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Quoting FloridaTigers:


Agreed, yet plagiarism by guys like jasoniscool and WeatherStudent goes unpenalized. Some sort of double standard.




Agree we need him!
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2722. Patrap
Quoting pcolasky:
Hey Pap, here in p'cola we had about an inch of rain


Yeah I saw that Band sit over that way this afternoon
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Quoting FloridaTigers:


Agreed, yet plagiarism by guys like jasoniscool and WeatherStudent goes unpenalized. Some sort of double standard.

I missed it- what was plagiarized?
Member Since: September 5, 2007 Posts: 0 Comments: 3482
? what will be in the GOM to prevent 94l from coming here? And Please Don't Yell at me just asking and innocent question.
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2719. jipmg
There goes our CAT 4
It's obvious the 94L will not be hitting a more northward turn, this baby is headed for some energy so It can grow into a big boy.
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agreed !!! we could use his knowledge and insight about now
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Hey Pap, here in p'cola we had about an inch of rain
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Hello all..94L does not look good at all. I still believe convection will start to blow-up and regenerate around 2-3 in the AM.
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Quoting Relix:
StormW ban should have waited. He's a great resource especially now, it was a pretty minor offense compared to other things here.


Agreed, yet plagiarism by guys like jasoniscool and WeatherStudent goes unpenalized. Some sort of double standard.
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Quoting GeoffreyWPB:
Shows you how complex weather is...within a few posts...clearly a northern component and another moving due west.



Agreed. A motion due N of W is not unusual but the quikscat pass shows clearly where the area of lowest pressure was at the time of the pass and that negates the previous WNW motion. Following what is happening with the cloud field will not necessarily determine where the surface low is.
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2711. Patrap



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Quoting Patrap:
tornadude just wu-mailed and said he also got a 24 hour Bann for off topic Images

I feel like "Publishers Clearinghouse" for the Banned.


Banned on the Run


OMG ROFLMAO
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Quoting marinetech47:


nothing here in New Iberia,,,,,not even a drizzle

Not a drop in Lafayette either.
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Quoting kmanislander:


Hi Pottery

These weak systems are a pain in the you know what. They appear to be going in several different directions at once.

Weak as it is I just don't see what would pull a Twave to the WNW. The low level flow controls the motion.
So the question is not when will it turn, but when will it intensify!
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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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