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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Not going to come anywhere near florida.
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Quoting NCHurricane2009:


60%! O_o

Ummmmmm........here comes Sandy
and probably no one is aware of this storm down there, hope they are listening to their local weather.....
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UKMET furthest west so far....


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...SPECIAL FEATURES...

TROPICAL WAVE EXTENDS FROM 12N71W TO 19N73W MOVING W AT 5-10 KT.
LOW-LEVEL CYCLONIC FLOW IS EVIDENT ON VISIBLE SATELLITE IMAGERY
WITH TOTAL PRECIPITABLE WATER IMAGERY ALSO INDICATING MAXIMUM
VALUES OF DEEP LAYER MOISTURE ACROSS THE CENTRAL CARIBBEAN
BETWEEN 69W-77W. UNORGANIZED SCATTERED MODERATE CONVECTION
ACCOMPANIES THE WAVE OVER A LARGE AREA FROM 11N-19N BETWEEN
64W-76W. WITH AN UPPER LEVEL ANTICYCLONIC CENTERED OVER THIS
TROPICAL WAVE
...ENVIRONMENTAL CONDITIONS ARE FORECAST TO BECOME
MORE FAVORABLE FOR DEVELOPMENT DURING THE NEXT DAY OR TWO AS THE
DISTURBANCE MOVES WESTWARD. THIS SYSTEM HAS A HIGH CHANCE OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

CARIBBEAN SEA...
WITH AN UPPER LEVEL TROUGH OVER THE EASTERN GULF OF MEXICO AND
WEAK MIDDLE TO UPPER LEVEL RIDGING OVER THE NW CARIBBEAN SEA...
THE WESTERN CARIBBEAN IS MOSTLY UNDER THE INFLUENCE OF A SURFACE
TROUGH ANALYZED ALONG 12N82W TO 15N83W TO 18N87W. LOW-LEVEL
MOISTURE CONVERGENCE IS MAXIMIZED ALONG THIS BOUNDARY WITH
SCATTERED SHOWERS AND TSTMS OCCURRING FROM 12N-20N W OF 82W.
MOST OF THIS ACTIVITY IS LOCATED OVER THE OPEN WATERS OF THE
WESTERN CARIBBEAN SEA...HOWEVER A FEW COASTAL SHOWERS ARE NOTED
ALONG THE NICARAGUA AND HONDURAS COASTS. FARTHER EAST...AN UPPER
LEVEL ANTICYCLONIC IS CENTERED NEAR 17N72W AND IS PROVIDING AN
OVERALL DIFFLUENCE ENVIRONMENT FOR THE TROPICAL WAVE ALONG 73W
TO FLOURISH CONVECTIVELY THIS AFTERNOON. A LARGE AREA OF
SCATTERED SHOWERS AND TSTMS ARE FOCUSED IN THE VICINITY OF THE
TROPICAL WAVE AS IT IMPACTS MUCH OF THE CENTRAL CARIBBEAN...
INCLUDING PORTIONS OF THE ABC ISLANDS AND SOUTHERN HISPANIOLA.
DEVELOPMENT OF ORGANIZED DEEP CONVECTION AND THE FORMATION OF A
CONSOLIDATED LOW LEVEL CIRCULATION CENTER WILL BE SLOW TO OCCUR
OVER THE NEXT FEW DAYS AS MANY OF THE GLOBAL MODELS SUGGEST A
RATHER BROAD AREA OF LOW PRESSURE ACROSS THE CENTRAL AND WESTERN
CARIBBEAN INTO MID-WEEK.
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Last Updated: Tuesday, September 25, 2012, 4:16 PM
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11
ST PETERSBURG --
On this date in 1848, the strongest hurricane that we know of hit Tampa Bay. Not much is known about the path, it probably formed in the Gulf of Mexico and came up the West-Coast of Florida. The hurricane made a direct hit on Pinellas County, coming ashore at Clearwater.

Although the only wind measurement (72 mph) is of a category 1 hurricane, the pressure and storm surge is more like a strong category 3 or even a category 4 hurricane. The pressure dropped to 28.18 inches or 945 mb and the storm surge was 15 feet.

The impact on the sparsely populated area was severe. Only five buildings were left standing in Tampa, and all were damaged. Fort Brooke was destroyed. Many of the trees in Pinellas County were toppled.

The “Gulf met the Bay” in Pinellas which was cut in half by the storm surge. Waters from Tampa Bay flowed back through the middle of Pinellas County to reach the Gulf of Mexico. Allen’s Creek was a half a mile wide at its mouth.

There wasn’t much else to damage around here in 1848, the population was only a few hundred. The Egmont Key Lighthouse had just been built, it was destroyed and had to be rebuilt. John’s Pass was cut on the coast of Pinellas and New Pass in Sarasota County.

Due to the low population of Florida at the time, there were no reported fatalities.

Then, a few weeks later, another hurricane hit the area on October 11, 1848. It was not as intense as the first 1848 hurricane but it still produced a 10 foot storm surge in Tampa Bay.

So, if anyone says the Tampa Bay area just can’t get hit by a major hurricane, remind them of the “Great Gale of ‘48”.
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Quoting LargoFl:
gee lets pray it does NOT..follow hurricane kings path....


60%! O_o

Ummmmmm........here comes Sandy
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Euro out to 72 hrs.

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253

WHXX04 KWBC 201739

CHGQLM

ATTENTION...NATIONAL HURRICANE CENTER



NCEP COUPLED GFDL HURRICANE MODEL FORECAST MADE FOR



TROPICAL DEPRESSION INVEST 99L



INITIAL TIME 12Z OCT 20



DISCLAIMER ... THIS INFORMATION IS PROVIDED AS GUIDANCE. IT

REQUIRES INTERPRETATION BY HURRICANE SPECIALISTS AND SHOULD

NOT BE CONSIDERED AS A FINAL PRODUCT. PLEASE SEE THE TPC/NHC

OFFICIAL FORECAST.





FORECAST STORM POSITION



HOUR LATITUDE LONGITUDE HEADING/SPEED(KT)



0 14.5 72.8 280./ 9.9

6 14.4 73.4 267./ 6.5

12 14.3 74.3 260./ 8.6

18 14.4 75.4 274./10.2

24 14.4 76.8 270./13.3

30 14.3 77.9 265./11.5

36 13.9 79.0 252./10.6

42 13.6 79.9 249./10.1

48 13.0 80.8 237./ 9.7

54 12.6 81.2 227./ 5.9

60 12.3 81.4 207./ 3.2

66 12.3 81.1 90./ 2.4

72 12.5 81.4 300./ 3.3

78 12.5 81.4 22./ .5

84 12.5 81.0 89./ 4.0

90 13.0 80.6 41./ 5.7

96 13.1 80.3 70./ 3.1

102 13.7 79.3 58./11.5

108 14.7 78.1 50./15.5

114 16.1 77.2 32./16.1

120 17.9 76.3 27./20.1

126 20.0 75.8 15./21.5


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gee lets pray it does NOT..follow hurricane kings path....
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King baby KING!!!! Would be interesting to have King Part 2 in Florida. Don't know much about it, but the path of King looks interesting.
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THX!:)
Quoting stormwatcherCI:
Scheduled for tomorrow.
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Quoting SFLWeatherman:
What day are they going to get a HH in 99L??
Tomorrow, I think. By then it might be a TD.
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241

NOUS42 KNHC 201446

REPRPD

WEATHER RECONNAISSANCE FLIGHTS

CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.

1045 AM EDT SAT 20 OCTOBER 2012

SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)

VALID 21/1100Z TO 22/1100Z OCTOBER 2012

TCPOD NUMBER.....12-154



I. ATLANTIC REQUIREMENTS

1. SUSPECT AREA (CENTRAL CARIBBEAN SEA)

FLIGHT ONE -- TEAL 71 FLIGHT TWO -- TEAL 72

A. 21/2100Z A. 22/1200Z

B. AFXXX 01EEA INVEST B. AFXXX 02EEA INVEST

C. 21/1630Z C. 22/0730Z

D. 16.0N 77.0W D. 16.0N 78.0W

E. 21/2030Z TO 21/2330Z E. 22/1100Z TO 22/1400Z

F. SFC TO 10,000 FT F. SFC TO 10,000 FT



2. OUTLOOK FOR SUCCEEDING DAY.....CONTINUE 12 HOUR FIXES

AT 23/0000Z NEAR 16.0N 79.0W IF SUSPECT AREA DEVELOPS.



II. PACIFIC REQUIREMENTS

1. NEGATIVE RECONNAISSANCE REQUIREMENTS.

2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.



$$

EC
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Quoting SFLWeatherman:
What day are they going to get a HH in 99L??
Scheduled for tomorrow.
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GFS at 144 hours..takes it away from florida..........................lets see what it says tomorrow
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Quoting SFLWeatherman:
What day are they going to get a HH in 99L??

Tomorrow... ATLANTIC REQUIREMENTS
1. SUSPECT AREA (CENTRAL CARIBBEAN SEA)
FLIGHT ONE -- TEAL 71 FLIGHT TWO -- TEAL 72
A. 21/2100Z A. 22/1200Z
B. AFXXX 01EEA INVEST B. AFXXX 02EEA INVEST
C. 21/1630Z C. 22/0730Z
D. 16.0N 77.0W D. 16.0N 78.0W
E. 21/2030Z TO 21/2330Z E. 22/1100Z TO 22/1400Z
F. SFC TO 10,000 FT F. SFC TO 10,000 FT
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Quoting hurricane23:


TY
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Quoting LargoFl:
can you post the GDFL please
GFDL 114 hrs.

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POSS T.C.F.A.
99L/INV/XX/XX
MARK
15.25N/72.19W
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Quoting LargoFl:
can you post the GDFL please


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126. Gorty
Off topic but I really want to know: Does a negative AO mean cold air could come down?
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THE NATIONAL WEATHER SERVICE IN SAN JUAN HAS ISSUED AN

* URBAN AND SMALL STREAM FLOOD ADVISORY
FOR THE FOLLOWING MUNICIPALITIES...

IN PUERTO RICO
MOCA...SAN SEBASTIAN...AGUADILLA...ISABELA...CAMUY AND
QUEBRADILLAS

* UNTIL 400 PM AST

* AT 159 PM AST...DOPPLER RADAR INDICATED NUMEROUS SHOWERS AND
THUNDERSTORMS IN THE ADVISORY AREA. THESE AREAS OF SHOWERS AND
THUNDERSTORMS HAVE THE CAPABILITY OF PRODUCING MODERATE TO HEAVY
RAINFALL WHICH WILL LEAD TO RAPID RISES ON SMALL STREAMS AND
CREEKS...AS WELL AS MINOR FLOODING ALONG ROADWAYS...THROUGH AT
LEAST 400 PM AST.

MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO
AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY
DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL
ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED
ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.

&&

LAT...LON 1849 6696 1849 6684 1836 6685 1837 6689
1829 6691 1841 6716 1851 6715 1852 6706

$$

23
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What day are they going to get a HH in 99L??
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Quoting hurricane23:


As another poster mentioned in another wx forum the overall pattern is somewhat similar to that of king 1950. Though leaning east of florida for now.
can you post the GDFL please
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GFS at 120 hours,flooding for the islands i bet.......
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Quoting nrtiwlnvragn:
HWRF and GFDL close, HWRF further west and a little faster.




As another poster mentioned in another wx forum the overall pattern is somewhat similar to that of king 1950. Though leaning east of florida for now.
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That is a big jump, 99L is up to 60%.
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99L starting to fan out and nice anti-cyclone with it:



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HWRF and GFDL close, HWRF further west and a little faster.


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Quoting SFLWeatherman:
12Z CMC not good for FL!
gee if that solution proves true east coast florida had better start checking their preps etc,even if it stays offshore,imagine the beach areas..lets hope it tacks a farther eastward track
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Quoting thunderbug91:

Trick or treat....
yes watching it closely now
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Fleet Weather Center Norfolk Virginia


No Active Atlantic Tropical Warnings
October-20-12, 1:45:01 PM | CDO.FWC.NRFK.fct@navy.mil (FWC-N CDO)
As of Sat, 20 Oct 2012 17:45:01 GMT
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2 pm puts it at 60%.......!
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99L 60%
CODE RED
90L same
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plenty of moisture for 99L to work with...barring a spike in shear, I don't see how this can be anything but a major in a couple of days. certainly wont be gulping dry air all the way like Ernesto did.
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Atlantic Tropical Weather Outlook


000
ABNT20 KNHC 201752
TWOAT

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT SAT OCT 20 2012

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

SATELLITE IMAGES INDICATE THAT SHOWERS AND THUNDERSTORMS HAVE BECOME
BETTER ORGANIZED IN ASSOCIATION WITH A TROPICAL WAVE LOCATED OVER
THE CENTRAL CARIBBEAN SEA. SURFACE PRESSURES ARE FALLING IN THE
AREA...AND ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BECOME
CONDUCIVE FOR A TROPICAL DEPRESSION TO FORM DURING THE NEXT COUPLE
OF DAYS. THIS SYSTEM HAS A HIGH CHANCE...60 PERCENT...OF BECOMING
A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS THE WAVE MOVES
SLOWLY WESTWARD.

DISORGANIZED CLOUDINESS AND THUNDERSTORMS CENTERED ABOUT 1000 MILES
EAST-NORTHEAST OF THE LEEWARD ISLANDS ARE ASSOCIATED WITH AN
UPPER-LEVEL LOW INTERACTING WITH A TROPICAL WAVE. UPPER-LEVEL
WINDS COULD BECOME A LITTLE MORE CONDUCIVE FOR DEVELOPMENT DURING
THE NEXT DAY OR SO. THIS SYSTEM HAS A LOW CHANCE...20 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES
WEST-NORTHWESTWARD AT ABOUT 10 MPH.

ELSEWHERE...TROPICAL STORM FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER BLAKE
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Up to 60 percent...2pm
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Quoting SFLWeatherman:
12Z CMC not good for FL!

Trick or treat....
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Quoting GTcooliebai:
12z CMC:

just off shore of miami like thats going to happen
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12Z CMC not good for FL!
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2pm TWO should be out momentarily.
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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.