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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Wow... after F5ing it for 1/2 an hour, I turn my attention for 15 minutes and voila!

Thanks for the new blog, Doc.
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INV/XX/97L
MARK
13.93N/39.27W
Member Since: July 15, 2006 Posts: 174 Comments: 54436
Late next week... That is just about a week from now.. No matter what you all say about models being unreliable, even though most models are in agreements of a Southeast USA hit, a week is not really that far away and people from Florida to NC need to be closely watching this storm and making sure ur prepared.
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I hope the HH find a closed LLC and td or ts winds people are going to go nuts if not
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Quoting alex14:

Henry meant to say Hurricane Hanna from 2008
Ok now that makes since. ;)
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T.C.F.W.
0XL93/INV/XX
16.06N/81.23W
Member Since: July 15, 2006 Posts: 174 Comments: 54436
Quoting Jax82:
So, just another 96 hours of staring at clouds spin with 97L until it may become something? Watching models flip flop with landfalls? Hearing recurve, fish storm and pump the ridge for 4 more days? Hooray!

LOL
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Cybrted,
Very true... Though with Dry air a pretty decent problem + 93L's Size a tropical storm fits the bill, though you can never outrule sudden RI if it were to filter out the dry air, and take advantage of the low shear/High TCHP
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Quoting kwgirl:
Hurricane Donna crossed the Florida Keys at Marathon, went into the GOM and they headed NE and affected the Carolinas. There is archival info on Donna on WU you can get.
Am in Key West KWgirl. Whats your feeling about us getting something?
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So, just another 96 hours of staring at clouds spin with 97L until it may become something? Watching models flip flop with landfalls? Hearing recurve, fish storm and pump the ridge for 4 more days? Hooray!
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Quoting LITHCAT:
Good morning-

Long time reader, first time poster. Can anyone tell me how "Invests" are numbered? They usually are in the 90's and the numbers are reused. Is there any methodology or just random numbers attached?
How Invest's are Numbered
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Quoting 34chip:
I thought Hurricane Donna went up FLorida northward, but accu weather made it sound like it went straight into the carolinas? Please help me understand this.

Henry meant to say Hurricane Hanna from 2008
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97L update. Now you'll see some models:

BEGIN
NHC_ATCF
invest_al972011.invest
FSTDA
R
U
040
010
0000
201108181510
NONE
NOTIFY=ATRP
END
INVEST, AL, L, , , , , 97, 2011, DB, O, 2011081812, 9999999999, , , , , , METWATCH, , AL972011
AL, 97, 2011081712, , BEST, 0, 127N, 335W, 25, 1009, DB, 0, , 0, 0, 0, 0,
AL, 97, 2011081718, , BEST, 0, 129N, 344W, 25, 1009, DB, 0, , 0, 0, 0, 0,
AL, 97, 2011081800, , BEST, 0, 132N, 356W, 25, 1009, DB, 0, , 0, 0, 0, 0,
AL, 97, 2011081806, , BEST, 0, 133N, 368W, 25, 1009, DB, 0, , 0, 0, 0, 0,
AL, 97, 2011081812, , BEST, 0, 135N, 379W, 25, 1009, DB, 34, NEQ, 0, 0, 0, 0, 1010, 175, 90, 0, 0, L, 0, , 0, 0, INVEST, S,
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Link This was donna track.
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Quoting Vincent4989:
Night Aussie, and good morning america.... i live on the other side of the world so good night.

Good night??? I ain't going anywhere yet.
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Quoting 34chip:
I thought Hurricane Donna went up FLorida northward, but accu weather made it sound like it went straight into the carolinas? Please help me understand this.
Hurricane Donna crossed the Florida Keys at Marathon, went into the GOM and they headed NE and affected the Carolinas. There is archival info on Donna on WU you can get.
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ime: 15:09:00Z
Coordinates: 16.35N 69.5333W
Acft. Static Air Press: 392.7 mb (~ 11.60 inHg)
Acft. Geopotential Hgt: 7,733 meters (~ 25,371 feet)
Extrap. Sfc. Press: -
D-value: 418 meters (~ 1,371 feet)
Flt. Lvl. Wind (30s): From 15° at 6 knots (From the NNE at ~ 6.9 mph)
Air Temp: -18.7°C (~ -1.7°F)
Dew Pt: -20.4°C (~ -4.7°F)
Peak (10s) Flt. Lvl. Wind: 7 knots (~ 8.0 mph)
SFMR Peak (10s) Sfc. Wind: -
SFMR Rain Rate: -
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Night Aussie, and good morning america.... i live on the other side of the world so good night.
Member Since: November 13, 2009 Posts: 2 Comments: 728
Good morning-

Long time reader, first time poster. Can anyone tell me how "Invests" are numbered? They usually are in the 90's and the numbers are reused. Is there any methodology or just random numbers attached?
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Thanks DRM. Don't guess it'll ever rain in TX.
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10,940.52
-469.69
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I thought Hurricane Donna went up FLorida northward, but accu weather made it sound like it went straight into the carolinas? Please help me understand this.
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Quoting tropicfreak:


Think they'll find a closed circulation?


Don't know, we'll find out. Hard to say atm.
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Looks like things are about to get real interesting!
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Quoting CorneliaMarie:
So, 93L is not set to hit New Orleans?

no, unless New Orleans has moved to Belize.
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Quoting tropicfreak:


Think they'll find a closed circulation?

Not sure.
Member Since: November 13, 2009 Posts: 2 Comments: 728
97L. It's already getting its freak on.


Click image for loop
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FWIW, 93L's small size makes it more prone to quicker and more unexpected periods of intensification or weakening.
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Quoting CybrTeddy:
Recon enroute to 93L atm.


Think they'll find a closed circulation?
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Thanks for the update masters, and thanks nea for putting emphasis on the NEW BLOG ENTRY posts.
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Recon enroute to 93L atm.
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Thanks Dr. M! Sorry another to miss TX :(
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Thanks Dr. Masters

by the time the storm reaches Belize on Saturday.
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Thanks Dr. Masters!
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thanks
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Thx Dr M.!
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Storm Relative 1km Geostationary Visible Imagery


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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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