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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The TWC says, 94L will move north of Puerto but affect the Northern Antilles, it maybe a close call for us.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Member Since: July 3, 2005 Posts: 423 Comments: 127810
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Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting LightningCharmer:



Cool - thanks!
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Member Since: July 3, 2005 Posts: 423 Comments: 127810
Quoting CaicosRetiredSailor:

http://www.asce.org/pressroom/news/display_press.cfm?uid=1469


As winds increase, pressure against objects is added at a disproportionate rate. Pressure against a wall mounts with the square of wind speed so that a threefold increase in wind speed gives a nine-fold increase in pressure. Thus, a 25 mph wind causes about 1.6 pounds of pressure per square foot. A four by eight sheet of plywood will be pushed by a weight of 50 pounds. In 75 mph winds, that force becomes 450 pounds, and in 125 mph winds, it becomes 1,250 pounds

Great facts. sort of along my thinking, mind is a bit muddled up atm.
Anyways I'm out. Thanks all for your condolences and prayers.
Cheers AussieStorm
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Quoting WeatherStudent:


TS could this still threaten SF in the long halt of things?


Thats my current forecast.....
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699. IKE
Quoting hurricane556:
gfs takes 94l into carribean


?


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Quoting hurricanehanna:

...I've never taken the time to learn how to read these graphics. Is there a chart that shows what each "flag" means?


Member Since: September 1, 2007 Posts: 0 Comments: 1276
Models not helping much. Obviously the models to the right are wrong and the models to the left have verified but intialise further west.

correct further east to further west on the map below.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
If you think we have it tough, look at this!
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The disturbance north of Panama bears watching. Convection has been persisting in this area and wind shear is favorable and forecasted to remain favorable according to those shear maps at hour 36 and 48. Also it appears an anticyclonic flow aloft is trying to develop over this disturbance as a shear axis moves westward with the upper level low now moving west in the NW Caribbean Sea near Belize and the Yucatan peninsula. This one is moving more NW.
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Yesterday here in NOLA we as a Family made time to attend a few events marking the 4th Anniversary of the Storm.


Hurricane Katrina builds bonds of belief


Member Since: July 3, 2005 Posts: 423 Comments: 127810
Quoting cirrocumulus:
On no, is Chicklit here? Just kidding.


Please make sure one uses proper grammer and spellin.....
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There is a interesting little spin north of Porto Rico that is moving west, although it barely shows up on the 8oomb map.
Member Since: August 18, 2008 Posts: 0 Comments: 3113
688. CaicosRetiredSailor
Thanks
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http://www.asce.org/pressroom/news/display_press.cfm?uid=1469


As winds increase, pressure against objects is added at a disproportionate rate. Pressure against a wall mounts with the square of wind speed so that a threefold increase in wind speed gives a nine-fold increase in pressure. Thus, a 25 mph wind causes about 1.6 pounds of pressure per square foot. A four by eight sheet of plywood will be pushed by a weight of 50 pounds. In 75 mph winds, that force becomes 450 pounds, and in 125 mph winds, it becomes 1,250 pounds
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Quoting hurricanehanna:

All I can say is YUCK


Pureto Rico looks like bullseye currently....It could change and go south and interact with land.....and go pooff...i doubt it tho.
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On no, is Chicklit here? Just kidding.
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gfs takes 94l into carribean
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Quoting LightningCharmer:
If I remember my physics correctly, wind speed and wind energy are not linear meaning a 1% increase in wind speeds is not a 1% increase in wind energy. One of the experts, please clarify so I don't have to dig out my old text books. LOL I know, we can scour the internet now days.
Inquiring minds want to know. I too thought it was exponential, not linear
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mid level steering...favor this for systems starting out...pretty strong agruement for west movement on both blobs...including 94L
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Quoting Patrap:


Beauty is in the Eye of the Beholder..


Beauty is in the "EYE"
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Quoting Chicklit:
Deep Steering


There is also low and mid steering graphics on this site.
PSUEWall

Chicklet - I've never taken the time to learn how to read these graphics. Is there a chart that shows what each "flag" means?
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Quoting futuremet:


It looks beautiful, doesn't it Pat?


Almost Wilma-esque
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Quoting Gorty:
Can the public access the SHIPS model? I found this link from Dr. Masters blog from the invest that became Danny: ftp://ftp.tpc.ncep.noaa.gov/atcf/stext/09082412AL9209_ships.txt

Seeing if it will ever get updatedm but it never did, lol.

So is the SHIPS model available to the public?

Thanks to anyone who helped.


You have a link to a specific storm and time (AL92 12Z). Use the General Link and then select the latest data.
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Looks like south Texas might get a little rain from Jimena.

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48 hour shear forecast...once past shear zone projected could take off...question is ..how south can 94L stay...
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Quoting Patrap:

ATCF images (Hurricane Track Models)



All I can say is YUCK
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Deep Steering


There is also low and mid steering graphics on this site.
PSUEWall
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New steering maps will be coming out soon.....Here is the current with my analysis that stay current as things update...
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Link
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Quoting futuremet:


It looks beautiful, doesn't it Pat?


Beauty is in the Eye of the Beholder..
Member Since: July 3, 2005 Posts: 423 Comments: 127810


36 hour shear forecast..if bears out 94L may have to fight some moderate shear...
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633. TheDawnAwakening

Thanks!
I had learned from the blog, that an anticyclone did not work against forming a cyclone.
Quoting KEHCharleston:
That one threw me at first. I figured and ANTIcyclone must be AGAINST a cylcone developing. If you are ANTI-war, then you are against it right?.
I could not have been more wrong. In this case think of anti as being opposite. An anticyclone rotates in the opposite way that a cyclone does. When positioned above a cyclone, then it provides venting.

Your explanation of anticylone is in depth an very informative - again thanks, much appreciated!

One more question, if you do not mind:

The time in the heading is not necessarily the time of the QuickSCAT, right? Where is the actual time?



Link Winds Buoy 41041
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ATCF images (Hurricane Track Models)


Member Since: July 3, 2005 Posts: 423 Comments: 127810
667. JLPR
Quoting Weather456:


true...I wasnt going on the NWS PR location tho


lol they are in denial =P
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current shear map..
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Quoting jipmg:


well can you tell the different from 15mph winds and 20mph winds? If you can then yes there is a clear difference..
I don't think most people are able to realistically determine wind speed without mechanical help.
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I. ATLANTIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.
3. ADDITIONAL DAY OUT LOOK: POSSIBLE FIXES
NEAR 18N 54W BEGINNING AT 01/1800Z.
4. REMARKS: ALL FLYING ON TROPICAL STORM DANNY
WAS CANCELED BY NHC AT 29/0700Z.
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Quoting Patrap:
Hurricane Jimena



It looks beautiful, doesn't it Pat?
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661. jipmg
Quoting hunkerdown:
Some people REALLY need to realize, very few homes, almost none, are built to withstand 150, 155 or 160 mph...with that being said, the difference between 5 mph will not be noticable. Again, I am not talking the difference between minimal cat 4 and 175 mph, I am talking maximum cat 4 and BORDERLINE cat 5...


155MPH CAT 4 vs a 156MPH CAT 5 has no difference in damage obviously, but there is a difference between a 155MPH CAT 4 and a 165MPH CAT 5.

What a difference a day makes.
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659. amd
a reminder of what cat 4 winds can do:

Link

specifically, watch the part from about 1 min to 1 min 30 seconds
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658. Gorty
Can the public access the SHIPS model? I found this link from Dr. Masters blog from the invest that became Danny: ftp://ftp.tpc.ncep.noaa.gov/atcf/stext/09082412AL9209_ships.txt

Seeing if it will ever get updatedm but it never did, lol.

So is the SHIPS model available to the public?

Thanks to anyone who helped.
Member Since: Posts: Comments:

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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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