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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Pretty much all the models have 99L going west then a sudden turn North.

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Quoting Grothar:
GFS ENSEMBLE



Early 18Z


I like how they all say that this system will make a complete u-turn in the SW CARB.
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GFS ENSEMBLE



Early 18Z


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The GFDL came in similar to the HWRF:

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12z UKMET showed solid development:

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Back later
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Quoting SFLWeatherman:
2PM

BAMD TAKES THIS CLOSE TO FLA.
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Quoting ncstorm:
Can someone post the metro centre 12z cmc run past 156 hours for those past Florida..I'm on my phone..tia

It's sticking with the Nor'Easter theme. Brings it close to the NC coast then it would logically head to the NE from there... this is the last frame:

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Quoting unknowncomic:
Good to know-maybe bad to know though.


Knowledge is power :-)
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Quoting kmanislander:
Anticyclone right on top of 99L. Good conditions all around right now.

Good to know-maybe bad to know though.
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Keeper posted some good pics but just to clarify we just had a very powerful solar flare, about as close to X class as you can get without actually getting there:



It was centered around a sunspot that has not yet rotated fully into view:

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2PM

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Anticyclone right on top of 99L. Good conditions all around right now.

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Can someone post the metro centre 12z cmc run past 156 hours for those past Florida..I'm on my phone..tia
Member Since: August 19, 2006 Posts: 13 Comments: 14418
Quoting CybrTeddy:
Surprised they went straight to 60%, the GFDL and HWRF are really excited about this. The CMC has done the best from what I can see so far with sniffing this system out. Surface pressures are falling already, organization continues. The general idea for track is for it to slow down and stall in the SW Caribbean, then hook NE towards Cuba. This is going to be an interesting one to watch.
Any idea if there is or will be an anti-cyclone over 99L?
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0900 UTC



9 hours later. Organizing quickly

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URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
247 PM EDT SAT OCT 20 2012

...AREAS OF FROST EXPECTED IN THE NORTH CAROLINA MOUNTAINS TONIGHT...

.LIGHT WINDS AND MOIST CONDITIONS ALONG WITH TEMPERATURES IN THE
30S WILL ALLOW FROST FORMATION IN MUCH OF THE MOUNTAINS OF WESTERN
NORTH CAROLINA LATE TONIGHT...LASTING INTO EARLY SUNDAY MORNING.

NCZ033-048>053-058-059-062>065-501-503-505-210300 -
/O.NEW.KGSP.FR.Y.0007.121021T0800Z-121021T1300Z/
AVERY-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCO MBE-GRAHAM-
NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-HENDERSON-
CALDWELL MOUNTAINS-BURKE MOUNTAINS-MCDOWELL MOUNTAINS-
INCLUDING THE CITIES OF...NEWLAND...SPRUCE PINE...BRYSON CITY...
WAYNESVILLE...ASHEVILLE...SYLVA...FRANKLIN...BREV ARD...
HENDERSONVILLE
247 PM EDT SAT OCT 20 2012

...FROST ADVISORY IN EFFECT FROM 4 AM TO 9 AM EDT SUNDAY...

THE NATIONAL WEATHER SERVICE IN GREENVILLE-SPARTANBURG HAS ISSUED
A FROST ADVISORY...WHICH IS IN EFFECT FROM 4 AM TO 9 AM EDT
SUNDAY.

* LOCATIONS...MOST OF THE NORTH CAROLINA MOUNTAINS.

* TEMPERATURES...LOWS IN THE MID TO UPPER 30S.

* WINDS...NORTH 5 MPH OR LESS.

* IMPACTS...FROST MAY DAMAGE OR KILL SENSITIVE VEGETATION.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FROST ADVISORY MEANS THAT FROST IS POSSIBLE. SENSITIVE OUTDOOR
PLANTS MAY BE KILLED IF LEFT UNCOVERED.

&&

$$
WIMBERLEY
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Quoting Tropicsweatherpr:
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS NATIONAL HURRICANE CENTER MIAMI FL
1843 UTC SAT OCT 20 2012

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE INVEST (AL992012) 20121020 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
121020 1800 121021 0600 121021 1800 121022 0600

LAT LON LAT LON LAT LON LAT LON
BAMS 14.6N 73.0W 15.0N 75.0W 15.2N 77.0W 15.0N 78.8W
BAMD 14.6N 73.0W 15.0N 74.7W 15.3N 76.0W 15.6N 77.0W
BAMM 14.6N 73.0W 14.9N 74.7W 15.1N 76.2W 15.1N 77.6W
LBAR 14.6N 73.0W 15.1N 74.7W 15.9N 76.1W 16.7N 77.5W
SHIP 25KTS 33KTS 43KTS 49KTS
DSHP 25KTS 33KTS 43KTS 49KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
121022 1800 121023 1800 121024 1800 121025 1800

LAT LON LAT LON LAT LON LAT LON
BAMS 14.6N 80.8W 13.3N 84.1W 11.8N 86.3W 11.2N 87.6W
BAMD 15.8N 77.8W 16.5N 79.0W 18.2N 79.7W 20.9N 80.3W
BAMM 15.1N 79.0W 14.8N 81.2W 14.4N 82.3W 16.4N 78.0W
LBAR 17.2N 78.5W 18.7N 80.1W 20.5N 80.9W 22.4N 80.6W
SHIP 57KTS 65KTS 64KTS 61KTS
DSHP 57KTS 65KTS 64KTS 61KTS

...INITIAL CONDITIONS...
LATCUR = 14.6N LONCUR = 73.0W DIRCUR = 280DEG SPDCUR = 8KT
LATM12 = 14.3N LONM12 = 71.6W DIRM12 = 282DEG SPDM12 = 10KT
LATM24 = 14.0N LONM24 = 69.7W
WNDCUR = 25KT RMAXWD = 120NM WNDM12 = 20KT
CENPRS = 1007MB OUTPRS = 1009MB OUTRAD = 180NM SDEPTH = S
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM


Notice the heading has dropped from 295 to 280 degrees and pressure down 1 mb from earlier. Sub tropical high pushing 99L down
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33 wxchaser97: 50 knot winds and a 970mb pressure, what's next with Rafael? I thought he was long gone but nope.
34 NCHurricane2009: Maybe its just due-diligence in tracking the remnants? Even if it tracks SE toward Europe...the warmest the waters are is 21 deg C on such a path...and I don't know if the cold core upper troughing is cold enough at those water temps for subtropical development...

Ain't no surprise. Before NHC temporarily Deactivated the ATCF on 17L, they were spittin' out models that predicted this loop southward that exRafael is now undergoing, along with its regeneration into a SubTropical or Tropical Storm.
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Quoting GraduateStudent2012:



Am back? You speak as if you know who I am?

At any rate, YES, that we do. Any chance of this being a threat to the Cayman & to Florida down the road?




This system is a potential threat to Cayman and Florida but it is way too early to make that call. I am paying more attention to the Canadian model ( CMC ) than the others for the time being.
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TROPICAL CYCLONE GUIDANCE MESSAGE
NWS NATIONAL HURRICANE CENTER MIAMI FL
1843 UTC SAT OCT 20 2012

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE INVEST (AL992012) 20121020 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
121020 1800 121021 0600 121021 1800 121022 0600

LAT LON LAT LON LAT LON LAT LON
BAMS 14.6N 73.0W 15.0N 75.0W 15.2N 77.0W 15.0N 78.8W
BAMD 14.6N 73.0W 15.0N 74.7W 15.3N 76.0W 15.6N 77.0W
BAMM 14.6N 73.0W 14.9N 74.7W 15.1N 76.2W 15.1N 77.6W
LBAR 14.6N 73.0W 15.1N 74.7W 15.9N 76.1W 16.7N 77.5W
SHIP 25KTS 33KTS 43KTS 49KTS
DSHP 25KTS 33KTS 43KTS 49KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
121022 1800 121023 1800 121024 1800 121025 1800

LAT LON LAT LON LAT LON LAT LON
BAMS 14.6N 80.8W 13.3N 84.1W 11.8N 86.3W 11.2N 87.6W
BAMD 15.8N 77.8W 16.5N 79.0W 18.2N 79.7W 20.9N 80.3W
BAMM 15.1N 79.0W 14.8N 81.2W 14.4N 82.3W 16.4N 78.0W
LBAR 17.2N 78.5W 18.7N 80.1W 20.5N 80.9W 22.4N 80.6W
SHIP 57KTS 65KTS 64KTS 61KTS
DSHP 57KTS 65KTS 64KTS 61KTS

...INITIAL CONDITIONS...
LATCUR = 14.6N LONCUR = 73.0W DIRCUR = 280DEG SPDCUR = 8KT
LATM12 = 14.3N LONM12 = 71.6W DIRM12 = 282DEG SPDM12 = 10KT
LATM24 = 14.0N LONM24 = 69.7W
WNDCUR = 25KT RMAXWD = 120NM WNDM12 = 20KT
CENPRS = 1007MB OUTPRS = 1009MB OUTRAD = 180NM SDEPTH = S
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM
Member Since: April 29, 2009 Posts: 75 Comments: 13995
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(clipped from a weather site)..The usual reliable computer models for two weeks now have been forecasting development in the SW Caribbean with genesis expected early next week. The predicted system would then meander for a couple days over open water and then get picked up by a front and lifted NE with potentially life-threatening deluges dropping down on the Caymans, Jamaica, Cuba, and the whole island of Hispaniola (Haiti and the DR). It is not predicted to reach over to Puerto Rico and the Virgin Islands as far as the heavy rainfall is concerned but high level debris clouds are. Newly declared invest 99L, the tropical wave which gave us more rainfall than Rafael, is the prime candidate. Small chance but I know some of you are thinking is it possible Wrong Way Lenny #2?
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Surprised they went straight to 60%, the GFDL and HWRF are really excited about this. The CMC has done the best from what I can see so far with sniffing this system out. Surface pressures are falling already, organization continues. The general idea for track is for it to slow down and stall in the SW Caribbean, then hook NE towards Cuba. This is going to be an interesting one to watch.
Member Since: July 8, 2005 Posts: 259 Comments: 23565
Does anyone has the 12z UKMET on intensity?
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Quoting LargoFl:
and probably no one is aware of this storm down there, hope they are listening to their local weather.....


Largo - a big "probably".Down "there" (as you so quaintly put it), people are generally very aware of developing tropical systems. Without being over dramatic, it can, unfortunately be a matter of life and death and, at this time of year, all too often develops quickly "on our doorstep".
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Derived from NHC's 20Oct.12pm ATCF data for ExtraTropicalStormRafael
CWRW-FourchuHead :: YYT-St.John's :: PIX-PicoIsland
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Quoting clwstmchasr:
I just don't see any model support that brings this into the GOM and threatens tampa.
Nobody is even saying it will get into the GOM. Most likely track after Jamaica, Eastern Cuba, and Haiti is the Bahamas and East Coast of FL. Depending on which models you choose to go with.
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Quoting GraduateStudent2012:


Mi socio, que bola? Long time no see, mi compadre!


You're back eh :-)??

Lots for you to watch this weekend.
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144 hrs.

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Member Since: July 15, 2006 Posts: 169 Comments: 53296
Good afternoon

Looking at the various model runs, the one thing they seem to have in common is that 99L takes a dive into the SW Caribbean just East of Southern Nicaragua. If that happens the system will likely sit there for some time and it will take a very strong trough to pull it up.

The Canadian has had a good handle on this for several days now, probably the best of the models so far IMO. The Euro and GFS had solutions that vacillated between first one system then a split system and have now largely come on board with the Canadian. The HWRF essentially follows the Canadian as well with the GFDL being farther East and more in line with the track forecast seen by the GFS and Euro.

With the Canadian having come to the West some from earlier runs a track between the Caymans and Jamaica across Cuba is a strong possibility and one I would lean towards for now.

The key will be speed and depth of the trough coupled with how quickly 99L deepens, assuming it does close off.
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Member Since: July 15, 2006 Posts: 169 Comments: 53296


LARGE EVENT HAS OCCURRED
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Quoting LargoFl:
and no one in his/her right mind..Wants one to hit florida,in this economy who here..wants to lose everything?..sorry..for sure NOT me.

Not saying I wanted one to hit Florida; I was just stating how long it has been.
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GFS at 7-days...........................
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Good afternoon everybody, pressure falling down rapidly at buoy 42058
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Quoting 12george1:

The whole state of Florida is overdue. No hurricane landfall since 2005 is a very long time.
and no one in his/her right mind..Wants one to hit florida,in this economy who here..wants to lose everything?..sorry..for sure NOT me.
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Quoting GraduateStudent2012:


Speak for yourself. Miami is DUE! Overdue, in fact. Click, clock!

The whole state of Florida is overdue. No hurricane landfall since 2005 is a very long time.
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Post 146. That storm is probably responsible for creating the nice barrier islands we have today. I know the 1921 Hurricane was responsible for creating Honeymoon and Caladesi Islands.
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Not going to come anywhere near florida.
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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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