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 Floodman:


Brother, this time of year they ALL look ominous


FLOOD!!!!!!
Member Since: September 16, 2007 Posts: 0 Comments: 3650
Quoting EastTexJake:


Also, you're talking about 1900 instruments and observations. How accurate are those positions and wind speed readings? Can they be any more than guestimations?


I was asking what amount of storms in History have survived/died over that area. Not sure if you were talking about the same thing I was. I guess it would have to depend on exactly what land was affected because some land is flat and some very mountainous.
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models are meant to be used
for guidance only
and donot depict
final outcome
things can and will change
Member Since: July 15, 2006 Posts: 174 Comments: 54434
Quoting bigwes6844:
Rita eva. that thang was a hurricane in new york! what the hell!


Are there any records of hurricane conditions in NY during that timeframe?
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Quoting P451:


What you would be right about is that 97L won't be a tropical storm in 24 hours. And when it's not then you can throw the whole model run out the window.

There's nothing to watch model wise until you have a well developed storm for it to initialize.

That's the point I'm trying to impress on the blog. The same blog that put a whole lot of faith into the same early models that ran on 93,92,91 - etc - which were proven to be completely incorrect.



so what do the people in the islands watch because they would be affected as early as Saturday? you cant discount the models when you have people from the islands watching this storm approach and then read what you say..intensity is one thing but you have to look at the track to have some type of guidance..
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Quoting SunnyDaysFla:
Now that NHC will not have HH data, what will they need to see to classify 93L as a TD? Buoy data, sat. presentation or what?

All of the above, plus proximity to populated areas, along with a healthy dose of old-fashioned gut feelings.
Member Since: November 8, 2009 Posts: 4 Comments: 13556
Quoting RitaEvac:
Didn't blow its top till it got past the Florida keys

Rita eva. that thang was a hurricane in new york! what the hell!
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180HR CMC (GEM-GLB):

Member Since: August 14, 2008 Posts: 4 Comments: 4977
Quoting SouthDadeFish:
Surface obs are first priority, but they are kind of sparse in this area. If we see a clearly closed LLC on satellite they will upgrade. They do the same for storms that are out of the reach of recon.


Thanks for the reply!
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Quoting AtHomeInTX:


But our ridge is supposed to back off of us to the NW.


Hi AtHome... you got mail
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How can a storm go all the way to almost 25 north at 60W and make it to the GOM is amazing. Not even supposed to happen, and to come all the way to TX is just beyond comprehension

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Quoting SunnyDaysFla:
Now that NHC will not have HH data, what will they need to see to classify 93L as a TD? Buoy data, sat. presentation or what?
Surface obs are first priority, but they are kind of sparse in this area. If we see a clearly closed LLC on satellite they will upgrade. They do the same for storms that are out of the reach of recon.
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Quoting Levi32:


It would be unwise to guarantee Texas' safety from such a system, but the ridge doesn't look like it backs away enough to allow a storm to punch directly into the state. A theoretical storm could get close, perhaps with the western side affecting eastern Texas, but a direct hit I would still think is unlikely in this pattern. Again, though, things can and do change in 10 days, sometimes by a lot.


Ok. Thanks. It was worth a shot. Lol. Desperate times and desperate measures and all that. :)
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Quoting TropicalWeatherGrl88:


That's amazing, what do you think the ratio is with storms that have survived/died in that area.


Also, you're talking about 1900 instruments and observations. How accurate are those positions and wind speed readings? Can they be any more than guestimations?
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Time: 17:04:00Z
Coordinates: 14.9167N 79.1667W
Acft. Static Air Press: 624.3 mb (~ 18.44 inHg)
Acft. Geopotential Hgt: 4,103 meters (~ 13,461 feet)
Extrap. Sfc. Press: 1012.3 mb (~ 29.89 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 230° at 17 knots (From the SW at ~ 19.5 mph)
Air Temp: 2.8°C (~ 37.0°F)
Dew Pt: -1.4°C (~ 29.5°F)
Peak (10s) Flt. Lvl. Wind: 18 knots (~ 20.7 mph)
SFMR Peak (10s) Sfc. Wind: -
SFMR Rain Rate: -
(*) Denotes suspect data

This was measured on the way back .
Member Since: April 29, 2007 Posts: 0 Comments: 7932
Ike's track is by far the most unprecedented track I've ever seen period.

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Quoting RM706:
Wave coming off the African coast looks ominous...


Brother, this time of year they ALL look ominous
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Quoting AtHomeInTX:


So TX would be out of the running even with the ridge backing off?


It would be unwise to guarantee Texas' safety from such a system, but the ridge doesn't look like it backs away enough to allow a storm to punch directly into the state. A theoretical storm could get close, perhaps with the western side affecting eastern Texas, but a direct hit I would still think is unlikely in this pattern. Again, though, things can and do change in 10 days, sometimes by a lot.
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624. THL3
Quoting cloudburst2011:


well i would be careful what you wish for wasnt it alecia that dumped 40 inches + on houston a few years back..


We sure could use some of that right now.
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just north of 97L
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Quoting TropicalWeatherGrl88:


That's amazing, what do you think the ratio is with storms that have survived/died in that area.


No telling
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See ya later guys!!!
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Quoting xtremeweathertracker:
This is from Accuweather.com site new story "While computer models are showing the southeastern U.S. as the main target, the wave could miss its expected northward turn and track into the western Gulf of Mexico or even the western Caribbean."


LOL... How is THAT for a forecast? At this point, we really can't rule anyone out... can we? I mean, perhaps England, Portugal and France should stay on alert too?!? (Sarcasm flag on)

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Now that NHC will not have HH data, what will they need to see to classify 93L as a TD? Buoy data, sat. presentation or what?
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Quoting RitaEvac:
Didn't blow its top till it got past the Florida keys



That's amazing, what do you think the ratio is with storms that have survived/died in that area.
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Quoting SouthDadeFish:
Lol that forecast pretty much covers everyone in the Atlantic Basin.


hits to the website..
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Quoting Levi32:


I don't know about the western Gulf of Mexico, but a track south of the islands and into the central-eastern gulf is still very much an option on the table. Again, details will be vague and could change on the models before we get the system developed, if it is indeed going to develop.


So TX would be out of the running even with the ridge backing off?
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Quoting P451:


Tropical Storm strength in 24 hours for 97L?

Yeah....no.

Here we go again....... the models haven't learned from their failures of 91L, 92L, and 93L and nor should they be expected to.

Will the bloggers who read them? They should be able to: Let's get a developed system before we start trusting these things.





um..even when they develop,they still dont get it right..emily, bret, cindy..I would rather be wrong in watching a model than to assume I am right and distrust the models and then have something bearing down on me without much notice
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Nice work.
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Quoting uptxcoast:


Unless some drastic changes occur with the steering patterns, no. This ridge-a-mortis (stole that from another member here...) is acting like a huge shield that will steer anything around it and to the south of us.

If a storm gets big enough it *Might* be able to punch though the ridge but any storm that big would be worse than the drought.


But our ridge is supposed to back off of us to the NW.
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sneak peak at 06Z HWRF run for 97L... more southern....for what it's worth!!
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About 3/4 of a circulation based on ASCAT. There could be west winds but would need HH to confirm that.





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Quoting TropicalWeatherGrl88:


Yes, but none have moved in there yet, and I will be very scared for the Gulf states if one does.


Don
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Quoting xtremeweathertracker:
This is from Accuweather.com site new story "While computer models are showing the southeastern U.S. as the main target, the wave could miss its expected northward turn and track into the western Gulf of Mexico or even the western Caribbean."


I don't know about the western Gulf of Mexico, but a track south of the islands and into the central-eastern gulf is still very much an option on the table. Again, details will be vague and could change on the models before we get the system developed, if it is indeed going to develop.
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Ike survived over Cuba, was officially a Cat II, but had storm surge of a Cat IV. I'm sure everyone's seen the pics of Crystal Beach, Bridge City, etc.... I would NOT be wishing for an invest with such a huge windfield NOW coming across whatEVER landmass and then hoping for a rain dumping. That kind of surge (a' la Ike) I don't ever want to see again, thank you very mush.
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Didn't blow its top till it got past the Florida keys

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Quoting xtremeweathertracker:
This is from Accuweather.com site new story "While computer models are showing the southeastern U.S. as the main target, the wave could miss its expected northward turn and track into the western Gulf of Mexico or even the western Caribbean."
Lol that forecast pretty much covers everyone in the Atlantic Basin.
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Quoting RitaEvac:


Been a lot of dry air out there, plus conditions so far this season just haven't been there either which is why we've had all tropical storms


Yes, but none have moved in there yet, and I will be very scared for the Gulf states if one does.
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Quoting P451:


Tropical Storm strength in 24 hours for 97L?

Yeah....no.

Here we go again....... the models haven't learned from their failures of 91L, 92L, and 93L and nor should they be expected to.

Will the bloggers who read them? They should be able to: Let's get a developed system before we start trusting these things.





Well their just statistical models. They just take the data they have and forecast from there. Statistical models aren't going to account for how long it takes to organize.
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Quoting wunderkidcayman:
I really hope they have another C-130 ready to fly out when AF300 lands I am abit upset that the plane had to crap up at this time (it the wrong moment to crap up!!!!!!!!!!!)



i just thank the lord they didnt have an accident and fatalities....
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Quoting RitaEvac:


Yea, don't want that setup
This is from Accuweather.com site new story "While computer models are showing the southeastern U.S. as the main target, the wave could miss its expected northward turn and track into the western Gulf of Mexico or even the western Caribbean."
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Quoting Levi32:


Probably not as much as it shows, but a track directly over the islands could also get it into the Gulf of Mexico, which could give it time over water to strengthen in that scenario. However, we still won't know much about the details of this track until we get the system to develop, if it indeed does.


Very true. I am starting to think the ECMWF model might be the best one this year. I know it usually under develops storms. GFS has been extremley consistant I just can't wait to see which one is crowned king with this particular storm.
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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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