Caribbean disturbance 93L to drench Honduras; 97L disturbance worth watching

By: Dr. Jeff Masters , 3:04 PM GMT on August 18, 2011

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A westward-moving tropical wave in the Central Caribbean a few hundred miles south-southwest of Jamaica, Invest 93L, has continued to increase in organization, and is close to tropical depression status. 93L is a small system, but has built up a respectable area of heavy thunderstorms around its center. A few low-level spiral bands are apparent on satellite imagery, but there is almost no upper-level outflow apparent, and a surface circulation is not obvious. 93L has moistened its environment somewhat over the past day, but dry air is still in evidence around the storm, particularly to the southeast, as seen on water vapor satellite images. Wind shear continues to be low, 5 - 10 knots. There is a hurricane hunter mission scheduled for this afternoon at 2pm EDT to see if a tropical depression is forming.


Figure 1. Morning satellite image of 93L.

Heavy rains from 93L will begin spreading over Northern Honduras and Northeast Nicaragua tonight. The forward motion of 93L will slow to 5 - 10 mph by Friday, so the storm could be a major rain event for Northern Honduras, with rain amounts of 4 - 8 inches likely by the time the storm reaches Belize on Saturday. Heavy rains will spread to Belize and Mexico's Yucatan Peninsula by Friday night or Saturday morning. The latest SHIPS model forecast shows wind shear remaining in the low range and the atmosphere steadily moistening over the next two days, which should allow 93L to reach tropical storm strength. All of the models agree that the ridge of high pressure steering 93L to the west will remain strong, forcing the storm into a landfall Friday in Northeast Honduras, or Saturday near the Belize/Mexico border. It is possible that 93L will have time to intensify into a Category 1 hurricane before then, though landfall as a tropical storm would be more likely, given the dry air that 93L needs to overcome, and the possibility that the storm will pass too close to the northern coast of Honduras. Regardless, heavy rain will be a major threat from 93L. NHC gave 93L an 80% chance of developing into a tropical depression by Saturday morning in their 8am outlook. If 93L does cross the Yucatan Peninsula and enters the Gulf of Mexico, a strong ridge of high pressure should keep the storm moving due west to make a second landfall along the Mexican coast, well south of Texas.


Figure 2. Morning satellite image of the tropical wave 97L midway between the Lesser Antilles and the coast of Africa.

Invest 97L midway between the Lesser Antilles and the coast of Africa
A tropical wave near 14°N 40°W, midway between the Lesser Antilles Islands and the coast of Africa, is moving westward near 15 - 20 mph. This wave, designated 97L by NHC this morning, has little heavy thunderstorm activity associated with it due to dry air, but an impressive amount of large-scale spin is obvious in visible satellite loops. 97L is expected to arrive in the Lesser Antilles Islands by Saturday. Over the past day, all four of our reliable models for predicting tropical storm genesis have predicted that this wave could develop into a tropical depression sometime Saturday through Monday, so 97L needs to be watched carefully. NHC gave 97L a 10% chance of developing into a tropical depression by Saturday morning in their 8am outlook, and it is unlikely that this storm will pose much of a threat to the Lesser Antilles. It will take several days for the storm to overcome the large amount of dry air surrounding it, even though wind shear is a low 5 - 10 knots. By Saturday, the wave will find a moister atmosphere and warmer sea surface temperatures near the northern Lesser Antilles, and more rapid development may occur. However, there is expected to be high wind shear associated with an upper level low pressure system to the north of Puerto Rico at that time, and this wind shear may interfere with development. 97L is expected to take a west-northwest track through the Northeast Caribbean bringing the storm near Puerto Rico by Sunday or Monday. Long-range model runs, which are highly unreliable, foresee that 97L could be a threat to Hispaniola, Eastern Cuba, the Bahamas, and Florida by the middle to end of next week.

Jeff Masters

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Quoting MississippiWx:


Please do.
hahaha
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the oil still washes ashore in louisiana.......
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tic toc tic toc tic toc, 0 hour we be upon us soon enough,with many more model runs to peruse,countless other variables to contend with..........it's all good, too many things can still happen, tic toc tic toc....lol
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2843. JRRP
00 GMT 08/19/11 13.6N 41.4W 25 1008 Invest
06 GMT 08/19/11 13.5N 44.2W 25 1007 Invest
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Oye yoy my head hurts, watching model run after run, I'm going to sleep. You all should too, since one things certain, were all safe tonight from any hurricane strike.
Member Since: August 31, 2009 Posts: 0 Comments: 5628
Quoting MississippiWx:


Please do.
LOLOLOLOL
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D-max helping TD8. Should be TS Harvey tomorrow sometime. Anyway, I'm out.

Member Since: July 15, 2006 Posts: 17 Comments: 10159
Quoting HurricaneHunterJoe:


possible center reformation in the red convection for TD #8?


Possible...
Member Since: July 15, 2006 Posts: 17 Comments: 10159
2837. WxLogic
Quoting scottsvb:
Dont look at anything until after it enters the carribean.

1 Does it interact with Hispaniola

2.Is it weaker and goes west thru Jamaica

3.Does it get stronger and feels the trough

4. How strong will the trough be


There are just too many questions... just look out to 3 days.. models will change each run.


And that they'll do for sure...
Member Since: August 14, 2008 Posts: 4 Comments: 4925
Still a lot of uncertainty in the models. However, the trend in the 00z runs is for a possible strong trof to pick it up out of the Caribbean and pull it just barely over extreme SE Florida, then up the Coast (CMC/ECMWF). GFS still says Central Gulf, but a lot farther east than 18z.
Member Since: July 15, 2006 Posts: 17 Comments: 10159
Dont look at anything until after it enters the carribean.

1 Does it interact with Hispaniola

2.Is it weaker and goes west thru Jamaica

3.Does it get stronger and feels the trough

4. How strong will the trough be


There are just too many questions... just look out to 3 days.. models will change each run.
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Quoting MississippiWx:


possible center reformation in the red convection for TD #8?
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2832. WxLogic
@192HR:

Member Since: August 14, 2008 Posts: 4 Comments: 4925
2831. 7544
oh jummm back to fla dizzy now and cmc also Link
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2830. WxLogic
Quoting MississippiWx:
If that strong of a trof comes down, recurvature east of Florida is a possibility.


Indeed... like NGP has been forecasting all along, but now coming a little bit in line with other major operational models.
Member Since: August 14, 2008 Posts: 4 Comments: 4925
If that strong of a trof comes down, recurvature east of Florida is a possibility.
Member Since: July 15, 2006 Posts: 17 Comments: 10159
2828. WxLogic
97L went down a MB:

AL, 97, 2011081906, , BEST, 0, 135N, 442W, 25, 1007, DB, 34, NEQ, 0, 0, 0, 0, 1010, 240, 120, 0, 0, L, 0, , 0, 0, INVEST, S,
Member Since: August 14, 2008 Posts: 4 Comments: 4925
Quoting PlyWoodNative2011:


You see???? Now this is a much more accurate and logic depiction of what may end up happening out this storm, ain't it, Mike? As you heard during tonight's show, JB called it all along, =). Kudos to him. This stands NO CHANCE of making it into the GOM, I'll bet my life on that.


Please do.
Member Since: July 15, 2006 Posts: 17 Comments: 10159
Quoting MississippiWx:
The difference in the strength of the trof the Euro is showing is pretty extreme. It's not even close. A trof THAT strong in August would be nuts.

12z:


00z:

Very similar to what the 0z CMC showed.
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2821. jonelu
Quoting weatherman12345:
looks like a fla hit this run
back and forth, back and forth...cant wait til we have a COC so the models will be more reliable... either way Im expecting a close call here in SEFL in the next 2 wks.
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The difference in the strength of the trof the Euro is showing is pretty extreme. It's not even close. A trof THAT strong in August would be nuts.

12z:


00z:

Member Since: July 15, 2006 Posts: 17 Comments: 10159
2819. WxLogic
Quoting MississippiWx:
The trof to the North is WAY stronger this run...



That one has been updated yet... here's how is supposed to look like:

Member Since: August 14, 2008 Posts: 4 Comments: 4925
2818. WxLogic
Models are attempting to get a handle on the strength of the Bermuda High and the approaching TROF over the MS Valley.

I need to gain some confirmation on this suspicion but the development of 98L has something to do on how far/strong the bridge between the Bermuda High and the Texas High evolve.
Member Since: August 14, 2008 Posts: 4 Comments: 4925
The trof to the North is WAY stronger this run...

Member Since: July 15, 2006 Posts: 17 Comments: 10159
2814. WxLogic
Looks like 00Z CMC wasn't too far off on this one as 97L attempts to take advantage of the weakness over extreme E GOM.
Member Since: August 14, 2008 Posts: 4 Comments: 4925
Quoting Levi32:


0z GFS
wow mobile/biloxi on this run...lol
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2812. WxLogic
On for a bit...

00Z ECMWF @168HR:

Member Since: August 14, 2008 Posts: 4 Comments: 4925
144 hours:

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Quoting weatherman12345:
link?


Link
Member Since: July 15, 2006 Posts: 17 Comments: 10159
Member Since: July 15, 2006 Posts: 17 Comments: 10159
97L finally becomes a tropical cyclone at 144 hours. It keeps pushing back formation, so development is still a question for sure.
Member Since: July 15, 2006 Posts: 17 Comments: 10159
2806. KEEPEROFTHEGATE (Mod)
Quoting MississippiWx:
Stronger convection is firing with TD8 now...

this should be the kicker to get it to TS class but then again land interaction may inhibit that outcome regardless region should be ready for heavy showers or periods of rain and gusty conditions
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Quoting Floodman:


The whole state...


:-)
Member Since: September 17, 2010 Posts: 0 Comments: 216
Quoting TropicalWeatherGrl88:


What part?


The whole state...
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Stronger convection is firing with TD8 now...

Member Since: July 15, 2006 Posts: 17 Comments: 10159
Quoting TropicalWeatherGrl88:
Stormchaser what is the difference in that HWRF that you use? It doesnt have a northern or blown up bias?
TIA


I'm not 100% sure since it's very new, but it seems like that one doesn't have as much of a northerly bias and the intensity is toned down a bit.
Member Since: June 9, 2007 Posts: 4 Comments: 15776
Stormchaser what is the difference in that HWRF that you use? It doesnt have a northern or blown up bias?
TIA
Member Since: September 17, 2010 Posts: 0 Comments: 216
2800. KEEPEROFTHEGATE (Mod)
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2798. lennit
Quoting Stormchaser2007:


Link


THANKS
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Quoting TomTaylor:
It's notorious for blowing up storms. It's got convective feedback issues just like the NAM and therefore it usually over does systems. Also had a poleward bias last year, not sure if they've changed the model at all to fix that, but it was pretty significant last year.


Thanks
Member Since: September 17, 2010 Posts: 0 Comments: 216
Quoting lennit:
Chaser you have a link for the HWRF ? TIA>


Link
Member Since: June 9, 2007 Posts: 4 Comments: 15776

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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.