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Tropical Storm TOMAS (Text)

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TROPICAL STORM TOMAS DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL212010
500 PM AST FRI OCT 29 2010
 
AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT INVESTIGATING THE
VIGOROUS TROPICAL WAVE LOCATED SOUTHEAST OF THE WINDWARD ISLANDS
FOUND A CLOSED SURFACE CIRCULATION...ALONG WITH FLIGHT-LEVEL WINDS
AND UNCONTAMINATED SFMR SURFACE WINDS THAT SUPPORT A 35-KT TROPICAL
STORM. AS A RESULT...ADVISORIES HAVE BEEN INITIATED ON TROPICAL
STORM TOMAS...THE NINETEENTH NAMED STORM OF THE 2010 SEASON.

THE INITIAL MOTION IS AN UNCERTAIN 295/15...DUE TO THE POSSIBILITY
OF REFORMATION OF THE LOW-LEVEL CENTER WITHIN THE CENTRAL DEEP
CONVECTION. TOMAS IS EXPECTED TO CONTINUE MOVING WEST-NORTHWESTWARD
FOR THE NEXT 48 HOURS...PASSING THROUGH THE WINDWARD ISLANDS IN
ABOUT 24 HOURS OR SO. AFTER THAT...THE BROAD TROUGH THAT IS LOCATED
OFF THE U.S. EAST COAST AND THE BAHAMAS IS FORECAST TO LIFT OUT TO
THE NORTHEAST...WHICH ALLOWS A RIDGE TO BUILD TO THE NORTH OF TOMAS
ACROSS THE GREATER ANTILLES...THE BAHAMAS...AND FLORIDA. THE
EASTERLY FLOW ON THE SOUTH SIDE OF THE RIDGE SHOULD FORCE TOMAS ON
MORE OF A WESTERLY TRACK THROUGH 96 HOURS. BY DAY 5...A SECOND MUCH
DEEPER TROUGH IS EXPECTED TO DIG SOUTHWARD INTO THE SOUTHERN PLAINS
AND SOUTHEASTERN U.S. AND CAUSE THE RIDGE AND ASSOCIATED STEERING
CURRENTS TO WEAKEN. THE RESULT SHOULD BE A SHARP DECREASE IN
FORWARD SPEED BY 120 HOURS. THE NHC MODEL GUIDANCE IS IN GOOD
AGREEMENT ON THIS DEVELOPING SCENARIO...EXCEPT FOR THE GFDL AND
HWRF MODELS...WHICH ARE CONSIDERED TO BE OUTLIERS AT THIS TIME. 
THE OFFICIAL FORECAST TRACK IS ALONG THE SOUTHERN EDGE OF THE
GUIDANCE ENVELOPE...BUT NOT AS FAR SOUTH AND WEST AS THE GFS...
ECMWF...AND UKMET MODELS...WHICH ARE DEPICTING A MUCH WEAKER AND
SMALLER TROPICAL CYCLONE THAN IS EXPECTED.
 
RECON AND SATELLITE DATA INDICATE THE LOW-LEVEL AND UPPER-LEVEL
CIRCULATIONS ARE NOT YET VERTICALLY ALIGNED...WHICH SHOULD RESULT
IN ONLY SLOW INTENSIFICATION IN THE NEAR TERM. HOWEVER...WITH A
CENTRAL PRESSURE OF 998 MB...VERY MOIST MID-LEVELS...AND LOW
VERTICAL SHEAR...IT WOULD NOT TAKE MUCH FOR TOMAS TO INTENSIFY AT A
FASTER THAN NORMAL RATE. WHILE NOT EXPLICITLY INDICATING RAPID
INTENSIFICATION...THE OFFICIAL INTENSITY FORECAST REFLECTS THESE
FAVORABLE ENVIRONMENTAL CONDITIONS...AND IS ABOVE THE SHIPS/LGEM
INTENSITY MODEL GUIDANCE.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      29/2100Z 11.1N  57.5W    35 KT
 12HR VT     30/0600Z 12.0N  59.5W    40 KT
 24HR VT     30/1800Z 12.9N  61.8W    50 KT
 36HR VT     31/0600Z 13.5N  64.0W    60 KT
 48HR VT     31/1800Z 14.1N  66.2W    70 KT
 72HR VT     01/1800Z 14.8N  70.4W    90 KT
 96HR VT     02/1800Z 15.2N  74.0W   100 KT
120HR VT     03/1800Z 16.0N  76.0W   100 KT
 
$$
FORECASTER STEWART
 
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