99L a heavy rainfall threat for Jamaica, Haiti, and Eastern Cuba

By: Dr. Jeff Masters , 2:35 PM GMT on October 21, 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 have a good degree of spin. These thunderstorms are beginning to organize into spiral bands, as seen on visible satellite loops. However, the amount of heavy thunderstorm activity is about the same as yesterday, and there are no signs of a surface circulation. An Air Force hurricane hunter aircraft is scheduled to investigate 99L this afternoon, but I expect this flight will be rescheduled for later.


Figure 1. Morning satellite image of Invest 99L.

Forecast for 99L
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. On Wednesday, a strong trough of low pressure to the north of 99L is expected to turn the storm to the north or north-northeast, which should put 99L in the vicinity of Jamaica on Wednesday and Eastern Cuba on Thursday. By Friday, 99L should be in the Central or Eastern Bahamas. It is unclear at this point whether or not the trough pulling 99L to the north will be strong enough to pull the storm all the way out to sea to the northeast; a narrow ridge of high pressure has the potential to build in over 99L late this week and force the storm west-northwest, with a potential threat to the western Bahamas and U.S. East Coast by next weekend. In their 8 am EDT tropical weather outlook, NHC gave 99L a 70% chance of developing into a tropical cyclone by Tuesday morning. 99L will be capable of bringing heavy rains of 5 - 10 inches, with isolated amounts of up to 15 inches in mountainous areas, to Jamaica and Haiti, Monday through Wednesday. Heavy rains will begin on Tuesday in Eastern Cuba, and spread northwards into the Central and Eastern Bahamas by Wednesday.

Invest 90L in the middle Atlantic
A tropical wave (Invest 90L) about 830 miles east-northeast of the northernmost Lesser Antilles Islands is headed west-northwest at about 10 mph. The disturbance has a small 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 providing 90L the spin it needs to become a tropical cyclone, but is also pumping cool, dry air into the disturbance, which will keep any development slow over the next few days. Wind shear is a moderate 10 - 20 knots, and is forecast to remain in the moderate range until Tuesday. This may allow for some slow development of 90L before it encounters high wind shear of 20 - 30 knots on Tuesday night through Thursday. None of the reliable computer models develop 90L into a tropical cyclone, and it's unlikely that 90L will affect any land areas. In their 8 am EDT tropical weather outlook, NHC gave 90L a 30% chance of developing into a tropical cyclone by Tuesday morning.

The next name on the list of Atlantic tropical storms for 2012 is Sandy.

Jeff Masters

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18z Surface Analysis.

Member Since: April 29, 2009 Posts: 75 Comments: 14214
310 PlazaRed: [Deep well-water extraction linked to deadly Spain quake]

Whenever ya think you're gettin' a free lunch, odds are high you're gonna get hit with a BIG bill afterward
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Quoting Jedkins01:



Floridians keep posting model runs of a big nor' easter without knowing what it means for Florida, lol. We could get winter cold with well below normal temps with that if model trends continue.

:)
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This show agreement and low risk to florida.
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Quoting weatherbro:


If the Euro and CMC pan out, Florida is gonna be well below average next week!!!



Floridians keep posting model runs of a big nor' easter without knowing what it means for Florida, lol. We could get winter cold with well below normal temps with that if model trends continue.
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Quoting PlazaRed:

I'm just looking at that chart you posted and wondering how the dates are configured?
It says Mon 12 1029
would this read as Monday 29th of October 2012 if they used a sensible system of dating things?
Would it not be simpler to put Monday 29,10, 2012?
Just a thought.

Heres something interesting about boring water wells and what might have gone wrong!
http://abcnews.go.com/Technology/wireStory/scient ists-link-deep-wells-deadly-spain-quake-17529413#. UIQsCIVGyIc


They give the year first, 12 then month and date.

2012 10-29

We don't put our dates backwards like you do in Europe. :) How you doing Plaza?
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Quoting SFLWeatherman:
From Garrett Bastardi

Link


Well, other than having the track for November rather than October, that's not too bad I guess.
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305 KEEPEROFTHEGATE: event detected

Seems like we're entering the Season of the Eventful Sun after the cool of the Quiet Sun...
...which makes me kinda think that the SouthernHemisphere is in for a HOT summer
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Does anybody feel that the models are going to shift more westward in time for invest 99??
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Member Since: July 15, 2006 Posts: 170 Comments: 53548
Quoting SFLWeatherman:
WOW!!! lol one of the 12z GFS ENSEMBLE MEMBERS

I'm just looking at that chart you posted and wondering how the dates are configured?
It says Mon 12 1029
would this read as Monday 29th of October 2012 if they used a sensible system of dating things?
Would it not be simpler to put Monday 29,10, 2012?
Just a thought.

Heres something interesting about boring water wells and what might have gone wrong!
http://abcnews.go.com/Technology/wireStory/scient ists-link-deep-wells-deadly-spain-quake-17529413#. UIQsCIVGyIc
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ECMWF making a "Perfect Storm" up the east coast in about 8 days.

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NOGAPS



gfs



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Here is the San Juan NWS afternoon discussion about the indirect effects for Puerto Rico.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
400 PM AST SUN OCT 21 2012

WE WILL CONTINUE TO MONITOR THE EVOLUTION OF THE
AFOREMENTIONED SURFACE LOW PRESSURE SYSTEM. THERE ARE STILL
TIMING AND TRACK DIFFERENCES...BUT LATEST MODELS HAVE GENERALLY
SHIFTED TO THE WEST AND NORTHWEST KEEPING THE SURFACE LOW ON A
TRACK EVEN FURTHER TO OUR WEST THROUGH NORTH. NONETHELESS...IT
STILL LOOKS LIKE THE LOCAL AREA WILL HAVE THE POSSIBILITY OF THE
INFLUX OF DEEPER TROPICAL MOISTURE...WITH VEERING WIND FLOW WITH
HEIGHT AND FAVORABLE UPPER LEVEL CONDITIONS...IN COMBINATION WITH
LOCAL EFFECTS...INCLUDING SOUTH TO NORTH OROGRAPHIC LIFTING ACROSS
THE CORDILLERA CENTRAL. DESPITE THE WESTWARD SHIFT OF POTENTIAL
MODEL TRACKS...THE CURRENT INDICATIONS WOULD STILL YIELD SEVERAL
DAYS OF UNSETTLED WEATHER LOCALLY...PROBABLY BEGINNING EARLY
WEDNESDAY...AND THEN CONTINUING THROUGH THURSDAY AND FRIDAY AND
PROBABLY BEYOND. ALTHOUGH IT IS STILL TOO EARLY FOR MANY
DETAILS...THE "POTENTIAL" REMAINS FOR LOCALLY HEAVY RAINFALL...
POSSIBLY FLOODING...LOCALLY SEVERE WEATHER AND INCREASINGLY
HAZARDOUS WINDS AND SEAS AT SOME POINT DURING THE EVENT. STAY
TUNED.
Member Since: April 29, 2009 Posts: 75 Comments: 14214
From Garrett Bastardi

Link
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event detected
Member Since: July 15, 2006 Posts: 170 Comments: 53548
Derived from NHC_ATCF data for Invest99L @ 21Oct.06pm
14.7n75.5w was reevaluated &altered
14.7n75.8w-14.6n76.9w are now the most recent positions

Posted cuz it's finally showing some of the southward movement that was predicted earlier
CDD-PuertoLempira :: PUZ-PuertoCabezas :: KIN-Kingston

The longest line is a straightline projection through 99L's 2 most recent positions to its closest approach to an inhabited coastline.
99L's center was headed toward passage over Laguna de Karata
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Quoting Sfloridacat5:
I'm very suprised by how slow the blog is with the tropical activity we have.
we really don't have anything yet just a couple of invests and doom model runs
Member Since: July 15, 2006 Posts: 170 Comments: 53548
Quoting Thundercloud01221991:
I am in Rochester, NY and those GFS model images scare me. That would be a ton of either snow or very cold rain.
stick around in a hour and a half the 18z gfs run will be coming up next
Member Since: July 15, 2006 Posts: 170 Comments: 53548
300. Gorty
Quoting Thundercloud01221991:
I am in Rochester, NY and those GFS model images scare me. That would be a ton of either snow or very cold rain.


How do you think I feel? I live in southern new england so coastal storms I am used to especially in winter and seeing that cold air coming toward the storm... gosh I hope the storm wont go coastal lol.
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I'm very suprised by how slow the blog is with the tropical activity we have.
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I am in Rochester, NY and those GFS model images scare me. That would be a ton of either snow or very cold rain.
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Quoting SLU:
Two days ago the models swept 99L out to sea but they are now showing a bomb exploding off the east coast by next weekend right in time for halloween.

Quoting OracleDeAtlantis:


Will it be trick, or ... ?

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296. whitewabit (Mod)
Predictions of tropical activity in the 2012 season Source Date Named
storms Hurricanes Major
hurricanes
Average (1950–2000)[4] 9.6 5.9 2.3
Record high activity 28 15 8
Record low activity 4 2 0†
–––––––––––––––– –––––––––––––––– –––––––––––––––– –––––
TSR December 7, 2011[5] 14 7 3
WSI December 21, 2011[6] 12 7 3
CSU April 4, 2012[7] 10 4 2
TSR April 12, 2012[8] 13 6 3
TWC April 24, 2012[9] 11 6 2
TSR May 23, 2012[10] 13 6 3
UKMO May 24, 2012[11] 10* N/A N/A
NOAA May 24, 2012[12] 9-15 4-8 1-3
FSU COAPS May 30, 2012[13] 13 7 N/A
CSU June 1, 2012[14] 13 5 2
TSR June 6, 2012[15] 14 6 3
NOAA August 9, 2012[16] 12-17 5-8 2-3
–––––––––––––––– –––––––––––––––– –––––––––––––––– –––––
Actual activity
17 9 1
* June–November only.
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295. Gorty
Idk about the rest of you, but for me, I am hoping this wont be coastal to allow cold air to get into my area... I do not want a historic snowstorm for two years in a row... and its creepy, its around the same time this year assuming the models wont change much.
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294. whitewabit (Mod)
Quoting TropicalAnalystwx13:
Nice to see I hit the nail on the head this season.



...Lol.


Don't feel bad .. I predicted 15/8/3 and thought I would be high when I posted it ...
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99L:

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HWRF hooks left towards sfl.

Member Since: May 14, 2006 Posts: 8 Comments: 13740
90L:

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Quoting Gorty:


which one is that?

Invest 90L and the percentage for it should be higher than 30%.

Quoting TropicalAnalystwx13:
Nice to see I hit the nail on the head this season.



...Lol.

Yours is doing the best job, not. At least it isn't every other forecasting center got it right and you got it wrong. I can't talk as I wasn't even here to make a prediction.
Member Since: March 16, 2012 Posts: 127 Comments: 7940
289. Gorty
Quoting Stormchaser2007:
Much closer to becoming a tropical cyclone than 99L right now.



which one is that?
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Much closer to becoming a tropical cyclone than 99L right now.

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Nice to see I hit the nail on the head this season.



...Lol.
Member Since: July 6, 2010 Posts: 113 Comments: 31895

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Quoting Grothar:


Well, I haven't missed one yet this year, but on this one, I am going to keep you in suspense.

I don't think we will know how close until about Wednesday. But I do think it is possible we will be in the "Cone of Uncertainty"


And the cone is only 2/3 of the possible track....

Ok then, I guess I will have to wait.
Member Since: March 10, 2006 Posts: 0 Comments: 10075
Quoting washingtonian115:
I'm rooting for out to sea! I know.From a prediction of just 12 to maybe 15 named storms at the most was forecasted by all the major weather outlets.Now we could be looking at possibly our 18th and 19th named storms in a few days.


That just shows you the value (or lack of) of an early season hurricane activity forecast. Doc masters says it every year, they have little to no skill....
Member Since: March 10, 2006 Posts: 0 Comments: 10075
283. Gorty
Quoting KEEPEROFTHEGATE:


I am not liking how that cold air is coming toward the storm. Gosh I hope I dont see a repeat of last Oct.
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Quoting Dakster:
Gro just tell me south Florida is not gonna get hit... I give you credit for calling very thing first.


Well, I haven't missed one yet this year, but on this one, I am going to keep you in suspense.

I don't think we will know how close until about Wednesday. But I do think it is possible we will be in the "Cone of Uncertainty"
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WOW!!! lol one of the 12z GFS ENSEMBLE MEMBERS
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Quoting Grothar:
Anybody notice the big model shift at the end? (Remember, I saw it first :):)




you seen nothing 1st



evere time you say that i be saying you seen nothing 1st
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Gro just tell me south Florida is not gonna get hit... I give you credit for calling very thing first.
Member Since: March 10, 2006 Posts: 0 Comments: 10075
Member Since: July 15, 2006 Posts: 170 Comments: 53548
Quoting Dakster:


I was going to say the gulf of Mexico.... But out to sea works too...
I'm rooting for out to sea!
Quoting HuracanTaino:
Wow, those predictions of an average 2012 hurricane seasons seems so long ago........
I know.From a prediction of just 12 to maybe 15 named storms at the most was forecasted by all the major weather outlets.Now we could be looking at possibly our 18th and 19th named storms in a few days.
Member Since: August 14, 2010 Posts: 10 Comments: 16828


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Quoting Grothar:
Anybody notice the big model shift at the end? (Remember, I saw it first :):)



The GFS has been showing a jump to the west before a more NNE movement.
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18Z






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boy am i happy the trough is coming to keep it away from louisiana or the GOM
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I just saw the Euro 12z, that would be one heck of a nor'easter. There would be lots of rain and wind and even a snow system in Michigan. Maybe this solution isn't all that crazy after all.
Member Since: March 16, 2012 Posts: 127 Comments: 7940
You can almost pick the coc on 99l where will it go
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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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