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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And now for something (not) completely different: CMC has a low form off Hatteras this evening with a pretty interesting sub-tropical structure and some impressive deepeening.

Link
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Quoting TropicalAnalystwx13:


We had a piece of energy break off from the frontal boundary located off the East Coast come here early this morning, unexpectedly produced a waterspout. My dad got a picture of it.



P.S. No, it isn't fake.


nice pic
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Quoting Levi32:


It's on the line lol. 2 hours ago I saw no westerly winds. I see evidence of some very weak ones now. It may take more than that to get the NHC to upgrade.
You are probably correct. 93L has taken a large step forward from yesterday though in terms of convection at d-min. Also, the pressure falls at a buoy roughly 100 miles away impress me.
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1343. Thrawst
Quoting TropicalAnalystwx13:
Q: What percentages will the National Hurricane Center give Invest 93L at 8PM?

A. 60%
B. 70%
C. 80%
D. 90%
E. ~100% or declaration

Q: What percentages will the National Hurricane Center give Invest 97L at 8PM?

A. ~0%
B. 10%
C. 20%
D. 30%
E. Lower/Higher or declaration

Q: What percentages will the National Hurricane Center give Invest 98L at 8PM?

A. ~0%
B. 10%
C. 20%
D. 30%
E. Lower/Higher or declaration

EBC.



E
B
B
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Quoting Levi32:


It's on the line lol. 2 hours ago I saw no westerly winds. I see evidence of some very weak ones now. It may take more than that to get the NHC to upgrade.
See post 1334.
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Back later
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1339. KEEPEROFTHEGATE (Mod)
INV/XX/97L
MARK
13.93N/43.27W
Member Since: July 15, 2006 Posts: 163 Comments: 52173
1338. DFWjc
Quoting xtremeweathertracker:
Does anyone know how to view satellite loops on an iPad since you can't use flash player, I'm at the hospital visiting my mom so I'm limited, but still trying to keep up!! LoL


Link
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The plane broke!
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1336. Levi32
Quoting SouthDadeFish:
Welcome aboard the "this-is-already-a-cyclone" camp Levi ;~)


It's on the line lol. 2 hours ago I saw no westerly winds. I see evidence of some very weak ones now. It may take more than that to get the NHC to upgrade.
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1335. Drakoen
Quoting kmanislander:


Would 98L not be too far West to feel that by then ?


No, the weakness continues to become better established as we speak.
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No one can't tell me that 93L isn't at least a T.D.If the NHC can give a name to Danny back in 09(Which was very ugly) then 93L deserves to be a T.D.
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Does anyone know how to view satellite loops on an iPad since you can't use flash player, I'm at the hospital visiting my mom so I'm limited, but still trying to keep up!! LoL
Member Since: May 31, 2011 Posts: 57 Comments: 566
1332. DFWjc
Quoting bohonkweatherman:
No wonder no one is answering in Dallas. :)


No that's about right, it's nasty outside here in North Richland Hills

Temperature
Heat Index
107 °F
Dew Point
58 °F
Wind
Speed / Dir
15.0 mph from South
Wind Gust
17.0 mph
Conditions
Pressure
29.79 in
Visibility
10.0 miles
Clouds
Clear -
Moisture
Humidity
20%
Rainfall
0.00 in
Snow Depth
Not available
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1331. KEEPEROFTHEGATE (Mod)
T.C.F.W.
0XL93/INV/XX
mark
16.06N/81.23W
Member Since: July 15, 2006 Posts: 163 Comments: 52173
3 days out...a little faster with 97L and a little further north as well (compared to the 12z):

Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting RitaEvac:
Dewpoint is screwed up

Bryan Parkway, Dallas, Texas (PWS)
Scattered Clouds
108.5 °F
Scattered Clouds
Humidity: 99%
Dew Point: 108 °F
Wind: 2.7 mph from the SE
Wind Gust: 6.0 mph
Pressure: 30.15 in (Rising)
Heat Index: 261 °F
No wonder no one is answering in Dallas. :)
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1326. DFWjc
Quoting BahaHurican:
Because it's fun???? We love to watch cyclogenesis?

So.... why are you here?


i come here for the comedy, see post above this reply....
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Quoting Drakoen:


Yes the trough over the Canary Islands


Would 98L not be too far West to feel that by then ?
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FULL IMAGE

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Quoting MississippiWx:
98L

Looking Jazzy! for a lack of better term.
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Quoting jascott1967:
Trying to gauge an invest is like gauging MLB prospects coming out of college. For every Albert Pujols's there are about 20 Matt Bush's. Why people on this board get so excited over an invest is beyond me, especially after all the weak storms and near storms we've seen this year.
Because it's fun???? We love to watch cyclogenesis?

So.... why are you here?
Member Since: October 25, 2005 Posts: 19 Comments: 20686
Quoting Levi32:
Within the last couple of hours, it does appear that some very weak westerly winds are beginning to appear on the south side of 93L. We are probably dealing with a tropical depression now, waiting for the NHC to become convinced.


Yeah, I'm thinking the center has made a jump to the north slightly in the convective ball. It had been on the SW periphery for most of the day, but it appears to have reformed a little farther north which could be bad for Belize.

Member Since: July 15, 2006 Posts: 17 Comments: 10156
Quoting Levi32:
Assuming 93L becomes Harvey, 98L could potentially beat 97L to Irene's name, forcing 97L to become Jose if it develops.
That is Awesome! :)
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Quoting Levi32:
Within the last couple of hours, it does appear that some very weak westerly winds are beginning to appear on the south side of 93L. We are probably dealing with a tropical depression now, waiting for the NHC to become convinced.
Welcome aboard the "this-is-already-a-cyclone" camp Levi ;~)
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Quoting Levi32:


The models generate a mid-upper low northwest of the system by 48 hours out. To me it looks like it appears out of nowhere, which is suspicious, but it is just possible that there is some upper vorticity in the region that we can't really see on satellite imagery, which the models spin up into a full-blown cut-off low within 2 days. We will see. I still have reservations about an immediate northwest movement like the models show.
This is typical of the pattern we see though. A system on the heels of another, will often be shunted northwest, for reasons that are expected, I imagine. The only time this seems to fail, is if the system is really weak.

Keep in mind, 97L has a large circulation, and isn't what we would expect, is some sort of upper low to form in the wake of it?

This is just common observation over the years. I have no technical name for this "on the heels" phenomena, but I'm sure someone here knows what this is called. It's probably very simple dynamics.
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Quoting Grothar:


You see that too, DraK?


The 48 hour forecast steering shows zonal flow to the West at all levels to near 60W

Saturday forecast steering layers
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1315. Drakoen
Quoting Grothar:


You see that too, DraK?


Yes the trough over the Canary Islands
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98L

Member Since: July 15, 2006 Posts: 17 Comments: 10156
1313. Levi32
Within the last couple of hours, it does appear that some very weak westerly winds are beginning to appear on the south side of 93L. We are probably dealing with a tropical depression now, waiting for the NHC to become convinced.
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Quoting MississippiWx:
Uhhh...93L is QUICKLY getting its act together. NHC will most likely declare this a TD, if not a TS at 8pm EST.

Yeah, there are very few times I question the NHC. But ummm.... idk what they are waiting for on this one.
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Quoting Tazmanian:




your welcome


plzs note that i may have too chang things with 93L right now i have it a bust but ma be not any more
Was just about to say, I see u r hanging on to the bust until you see a renumber.... lol
Member Since: October 25, 2005 Posts: 19 Comments: 20686
1310. KEEPEROFTHEGATE (Mod)
Member Since: July 15, 2006 Posts: 163 Comments: 52173
1309. MTWX
Quoting MississippiWx:


Yeah, it's already falling apart. It was coming at me, then died for the most part.

Took out the Jackson NEXRAD though...
Message Date: Aug 18 2011 20:23:07

KDGX REMAINS DOWN...LIGHTNING STRIKE HAS DAMAGED EQUIPMENT AND THE RADAR WILL RE
MAIN DOWN UNTIL AT LEAST 430 PM. FURTHER UPDATES WILL BE POSTED WHEN KNOWN. /CME
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Seems like 97L shouldn't develop until Sunday afternoon at the earliest.
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There may not be too much doubt where the current MJO is and headed along the ITCZ towards the Atlantic Basin....Just look at the location of TS Fernandina/Hurricane Greg in the E-Pac and the current location of 93L all lined up in a nice little row.

I have mentioned this several times now this season (looking for one of the Pro's to write a paper on the topic) on how active the E-Pac and Atlantic have been at the same time this year thus far....Lot's of storms in both basins this year so far.
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This is Harvey

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Uhhh...93L is QUICKLY getting its act together. NHC will most likely declare this a TD, if not a TS at 8pm EST.

Member Since: July 15, 2006 Posts: 17 Comments: 10156
Quoting MississippiWx:
Uhhh...93L is QUICKLY getting its act together. NHC will most likely declare this a TD, if not a TS at 8pm EST.



It is getting its act together pretty quickly now, should be a Tropical Depression VERY shortly.
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1303. THL3
Quoting RitaEvac:
Port of Houston, Houston, Texas (PWS)
Scattered Clouds
107 °F
Scattered Clouds
Humidity: 36%
Dew Point: 74 °F
Wind: 8.0 mph Variable
Wind Gust: 8.0 mph
Pressure: 29.82 in (Falling)
Heat Index: 122 °F


That makes me feel better. 103 here with 113 heat index in northern Waller county.
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1301. Grothar
Quoting Drakoen:


Big weakness in the eastern Atlantic. To induce poleward movement of 98L.


You see that too, DraK?
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Quoting TropicalAnalystwx13:
Q: What percentages will the National Hurricane Center give Invest 93L at 8PM?

A. 60%
B. 70%
C. 80%
D. 90%
E. ~100% or declaration

Q: What percentages will the National Hurricane Center give Invest 97L at 8PM?

A. ~0%
B. 10%
C. 20%
D. 30%
E. Lower/Higher or declaration

Q: What percentages will the National Hurricane Center give Invest 98L at 8PM?

A. ~0%
B. 10%
C. 20%
D. 30%
E. Lower/Higher or declaration

EBC.


EDD
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Uhhh...93L is QUICKLY getting its act together. NHC will most likely declare this a TD, if not a TS at 8pm EST.

Member Since: July 15, 2006 Posts: 17 Comments: 10156
1297. Grothar
img src="">
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Quoting CaicosRetiredSailor:
only one of those runs that seem logical based on current conditions is BAMS.... unless the models expect the ULL to rapidly move east...

Quoting MississippiWx:
If 93L isn't at least a TD right now, I will eat my computer.

Be kinda hard to blog like that... unless u can keystroke with your intestines...
Member Since: October 25, 2005 Posts: 19 Comments: 20686

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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.