Caribbean disturbance 99L a dangerous rainfall threat for Haiti, Jamaica, and Cuba

By: Dr. Jeff Masters , 4:12 PM GMT on October 20, 2012

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A tropical wave embedded in a large trough of low pressure (Invest 99L) covers a large portion of the Central Caribbean between Hispaniola and the northern coast of South America. This storm has the potential to be a dangerous rainfall threat for Haiti, Jamaica, and eastern Cuba. The disturbance is headed west at less than 5 mph, is over very warm waters of 29°C, and is in a moist environment. 99L has a large area of heavy thunderstorms that are beginning to show some organization, as seen on visible satellite loops. Wind shear is a low 5 - 10 knots, and is forecast to be in the low to moderate range, 5 - 20 knots, through Tuesday. This should allow for some steady development of 99L, and there has been a good deal of model support for 99L becoming a tropical depression by Wednesday. Steering currents favor a continued slow westward movement for 99L through Tuesday, which will bring a multi-day period of heavy rains to Haiti, Jamaica, and eastern Cuba beginning on Sunday. The Dominican Republic may also see some heavy rains, though not as great. On Wednesday, a strong trough of low pressure will approaching the Eastern U.S., and the GFS and ECMWF models predict that this trough will turn 99L to the north, bringing the storm into the southeast Bahama Islands on Thursday or Friday. In their 8 am EDT tropical weather outlook, NHC gave 99L a 30% chance of developing into a tropical cyclone by Monday morning. I put these odds higher, at 40%. An Air Force hurricane hunter aircraft is scheduled to investigate 99L on Sunday afternoon.


Figure 1. Morning satellite image of Invest 99L.

Invest 90L in the middle Atlantic
A tropical wave (Invest 90L) about 1000 miles east-northeast of the northernmost Lesser Antilles Islands is headed west-northwest at about 10 mph. The disturbance has a modest amount of heavy thunderstorms, as seen on visible satellite images, and has gotten tangled up with an upper-level low pressure system. This upper-level low is pumping cool, dry air into the disturbance, which will keep any development slow over the next few days. Wind shear is a high 20 - 25 knots, but is forecast to drop to the moderate range, 10 - 20 knots, Sunday through Monday. This may allow for some slow development of 90L before it encounters very high wind shear of 20 - 40 knots on Tuesday and Wednesday. None of the reliable computer models develop 90L into a tropical cyclone. It's unlikely that 90L will affect any land areas. In their 8 am EDT tropical weather outlook, NHC gave 90L a 20% chance of developing into a tropical cyclone by Monday morning.

Jeff Masters

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Quoting sunlinepr:


Inclusive la radciacion de microhondas de la estacion situada en el area de Cuba-Florida han afectado tus conclusiones meteorologicas... se nota... Ah perdon le deseo exito Sr...
Wow, "tiraera" meteorológica in Spanish style, cool !!!
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Member Since: August 2, 2010 Posts: 21 Comments: 9656
If we're going to do different languages, can we do Scottish Gaelic, French, or German? :P
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Adios, muchacos'



Lawdy, ratings really are way down seems.
Member Since: July 3, 2005 Posts: 415 Comments: 125681
Whoa...look at 90L getting better organized about 48W-20N...I think the 18Z ASCAT pass was on to something...
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Quoting washingtonian115:
That's actually from Dolly not Isaac.I'm not to sure who decided to take cycloneOz's video and run off with it like that.It needs to be taken down for giving people false alarms.


Thats Hwy 90 in Biloxi.

And er,Brian sent that to me sweetie.

Mabe check da date.


Published on Aug 29, 2012 by ohhellmaybe

Hurricane Isaac Scary Footage
Biloxi, Mississippi

: )
Member Since: July 3, 2005 Posts: 415 Comments: 125681
397. whitewabit (Mod)
Quoting beell:


I think it might be because "it" represents the models trying to develop a surface low within the very large, broader low that will ease out to the NE or ENE as SE US ridging lifts north. If anything develops,it will remain embedded in the parent low and NOT follow what appears to be straight-forward easterly steering flow. Steering may be more like a cork bobbing around a whirlpool-as the whirlpool itself moves.

I don't think you can treat this as a normal tropical system. You could could almost call "it" a "monsoon depression.

A few words from Dr. Steve Lyons in 2007-some of it seems to "fit"

The term has gained ascendancy in use to refer to a broad tropical cyclonic circulation characterized by 1) its large size, where the outermost closed isobar may have a diameter on the order of 600 n mi (1000 km); 2) a loosely organized cluster of deep convective elements, which may form an elongated band of deep convection in the east semicircle; 3) a low- level wind distribution that features a 100 n mi (200 km) diameter light-wind core, which may be surrounded by a band of gales or contain a highly asymmetric wind field; and 4) a lack of a distinct cloud system center. Most monsoon depressions that develop in the western North Pacific eventually acquire persistent central convection and accelerated core winds, marking their transitions into conventional tropical cyclones.

Then again, maybe not!


Thank you for your answer ...
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99L doesn't look too convective at the moment but I guess is the D-MIN period.
Member Since: April 29, 2009 Posts: 75 Comments: 13332
Quoting sunlinepr:



Tendriamos una tormenta Vira...

A Backwards storm
Well , "vira", a pasado antes, like Lenny...
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What happens when fog lifts in California?
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Quoting Patrap:
"Classic" er, well you know who.

: )

That's actually from Dolly not Isaac.I'm not to sure who decided to take cycloneOz's video and run off with it like that.It needs to be taken down for giving people false alarms.
Member Since: August 14, 2010 Posts: 10 Comments: 15734
Quoting sunlinepr:


Inclusive la radciacion de microhondas de la estacion situada en el area de Cuba-Florida han afectado tus conclusiones meteorologicas... se nota... Ah perdon le deseo exito Sr...




take this too your own blog plzs this is not a Spanish blog
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TPHBB
Member Since: August 2, 2010 Posts: 21 Comments: 9656
Quoting HuracanTaino:
I know,did you see when the COC was approaching Vieques it regenerate in a few hours next to San Martin a jump of almost 70miles to NE....

Such a jump is common in a sheared tropical storm whose t-storms are displaced to the NE and whose surface center is broadly defined rather than tightly defined. That's what happened in Rafael...
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Quoting GraduateStudent2012:


Hazme el favor y no compartas tus conspiraciones meteorologas conmigo porque no me interesan en lo mas minimo!

De acuerdo?


Inclusive la radciacion de microhondas de la estacion situada en el area de Cuba-Florida han afectado tus conclusiones meteorologicas... se nota... Ah perdon le deseo exito Sr...
Member Since: August 2, 2010 Posts: 21 Comments: 9656
"Classic" er, well you know who.

: )

Member Since: July 3, 2005 Posts: 415 Comments: 125681
386. beell
Quoting whitewabit:
What are the models seeing to turn it north so quickly??


I think it might be because "it" represents the models trying to develop a surface low within the very large, broader low that will ease out to the NE or ENE as SE US ridging lifts north. If anything develops,it will remain embedded in the parent low and NOT follow what appears to be straight-forward easterly steering flow. Steering may be more like a cork bobbing around a whirlpool-as the whirlpool itself moves.

I don't think you can treat this as a normal tropical system. You could could almost call "it" a "monsoon depression.

A few words from Dr. Steve Lyons in 2007-some of it seems to "fit"

The term has gained ascendancy in use to refer to a broad tropical cyclonic circulation characterized by 1) its large size, where the outermost closed isobar may have a diameter on the order of 600 n mi (1000 km); 2) a loosely organized cluster of deep convective elements, which may form an elongated band of deep convection in the east semicircle; 3) a low- level wind distribution that features a 100 n mi (200 km) diameter light-wind core, which may be surrounded by a band of gales or contain a highly asymmetric wind field; and 4) a lack of a distinct cloud system center. Most monsoon depressions that develop in the western North Pacific eventually acquire persistent central convection and accelerated core winds, marking their transitions into conventional tropical cyclones.

Then again, maybe not!
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Quoting NCHurricane2009:

If GFS is right. But if CMC is right...this could be a rare example of a Caribbean October storm making a bee-line to south Florida...then perhaps up the east coast (like the CMC seems to suggest)....
Well it is the CMC we're talking about.Ha ha!.
Quoting allancalderini:
Yep might affect Nicaragua a little before it is eject to Cuba.
With the fronts coming down I the U.S could be spared.It looks like you guys will once again have to take the brunt of another system.
Member Since: August 14, 2010 Posts: 10 Comments: 15734
Quoting NCHurricane2009:


Unless the CMC is right. That CMC run from today made my eyes bug pop out. However...I don't think the CMC is the most reliable model...but hey its a possibility....

That is true and the CMC has had a decent handle on 99L so far. It could happen but right now I wouldn't bet my life on it.
Member Since: March 16, 2012 Posts: 123 Comments: 7890
Someone is violating a Court Order.

LOL
Member Since: July 3, 2005 Posts: 415 Comments: 125681
Quoting sunlinepr:


Rafael fue un gran experimento... Lograron hacerlo cambiar de curso... gracis al radioObservatorio de Arecibo...

Rafael - weather lab. experiment...
I know,did you see when the COC was approaching Vieques it regenerate in a few hours next to San Martin a jump of almost 70miles to NE....
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Published on Aug 28, 2012 by Charles Walton


Wunderteam NOLA member

The Powerful Force of Hurricane Isaac could be seen and felt on Lakeshore Drive in New Orleans


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Quoting wxchaser97:

Then it would be moving ENE? I don't think that is going to happen. I also don't think it is going to hit the USA. 99L should probably continue W and the turn N and go toward Hispaniola and Cuba as a strong TS/cat1.


Unless the CMC is right. That CMC run from today made my eyes pop out. However...I don't think the CMC is the most reliable model...but hey its a possibility....
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Member Since: August 2, 2010 Posts: 21 Comments: 9656
Quoting washingtonian115:
Looks like this will be more of a caribbean threat than a U.S threat right?.
Yep might affect Nicaragua a little before it is eject to Cuba.
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Quoting washingtonian115:
Looks like this will be more of a caribbean threat than a U.S threat right?.

If GFS is right. But if CMC is right...this could be a rare example of a Caribbean October storm making a bee-line to south Florida...then perhaps up the east coast (like the CMC seems to suggest)....
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Quoting HuracanTaino:
Hey, guys,,what if,it begins moving ENE...more or less like Lenny?

Then it would be moving ENE? I don't think that is going to happen. I also don't think it is going to hit the USA. 99L should probably continue W and the turn N and go toward Hispaniola and Cuba as a strong TS/cat1.
Member Since: March 16, 2012 Posts: 123 Comments: 7890
Quoting HurricaneHunterJoe:
¿Cualquier posibilidad del lío en el título de Caribe a Florida? ¿O más son las Bahamas probables?
Joe are you using google's translations...that expression in Spanish sounded odd...to me to say the least...
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Quoting GraduateStudent2012:


Ninguna, no sean gandidos! No se quedaron conformados con este ultimo ciclon que los afecto recienmente?

El tal Rafael creo que se llamo!

Ustedes boricuas quieren que todos los afecten!

Y en Cajones


Rafael fue un gran experimento... Lograron hacerlo cambiar de curso... gracis al radioObservatorio de Arecibo...

Rafael - weather lab. experiment...
Member Since: August 2, 2010 Posts: 21 Comments: 9656
Looks like this will be more of a caribbean threat than a U.S threat right?.
Member Since: August 14, 2010 Posts: 10 Comments: 15734
Quoting HuracanTaino:
Hey, guys,,what if,it begins moving ENE...more or less like Lenny?

This is possible if the more easterly GFS solution plays out...but it won't turn more easterly until it exits the Caribbean...so not quiet like Lenny...
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Quoting HuracanTaino:
Hey, guys,,what if,it begins moving ENE...more or less like Lenny?



Tendriamos una tormenta Vira...

A Backwards storm
Member Since: August 2, 2010 Posts: 21 Comments: 9656
Quoting sunlinepr:


Por el momento los modelos la ponen sobre Jamaica y Cuba...

Jamaica & Cuba up to now...
Hey, guys,,what if,it begins moving ENE...more or less like Lenny?
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hr 162

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Member Since: August 2, 2010 Posts: 21 Comments: 9656
Quoting NCHurricane2009:

Just released a blog update that summarizes all the info on 90-L and 99-L for those that are seeing these things for the first time....
Member Since: August 14, 2010 Posts: 10 Comments: 15734
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Quoting Patrap:
Whatever happened to the cow that was lifted into the air by the tornado?

Felt somewhere? ;) sorry, couldn't help it...
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Quoting Patrap:
Whatever happened to the cow that was lifted into the air by the tornado?




"Udder disaster!"
Member Since: July 3, 2005 Posts: 415 Comments: 125681
hr 153

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Quoting HurricaneHunterJoe:
¿Cualquier posibilidad del lío en el título de Caribe a Florida? ¿O más son las Bahamas probables?


Por el momento los modelos la ponen sobre Jamaica y Cuba...

Jamaica & Cuba up to now...
Member Since: August 2, 2010 Posts: 21 Comments: 9656
Quoting washingtonian115:
What's been happening?.And is the blog finally calm?

Just released a blog update that summarizes all the info on 90-L and 99-L for those that are seeing these things for the first time....
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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.