Tropical Storm TOMAS

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TROPICAL STORM TOMAS DISCUSSION NUMBER  33
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL212010
500 AM EDT SAT NOV 06 2010
 
AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INVESTIGATING TOMAS
FOUND 700-MB FLIGHT-LEVEL WINDS OF 63 KT...PEAK SURFACE SFMR WINDS
OF 50-55 KT....AND A CENTRAL PRESSURE OF 993 MB. SATELLITE IMAGERY
SHOWS THAT THE THE CONVECTIVE STRUCTURE OF THE CYCLONE CONSISTS OF
A CENTRAL MASS OF COLD-TOPPED CONVECTION...THOUGH CLOUD TOPS HAVE
BEEN WARMING RECENTLY. THE AIRCRAFT OBSERVATIONS ALSO INDICATE THAT
THE SURFACE AND FLIGHT-LEVEL CENTERS ARE MORE ALIGNED THAN THEY
WERE PREVIOUSLY. WITH NO OBSERVATIONS TO SUPPORT HURRICANE FORCE
WINDS...THE INITIAL INTENSITY IS LOWERED TO 60 KT FOR THIS
ADVISORY. TOMAS IS EXPECTED TO REMAIN IN RELATIVELY LOW VERTICAL
WIND SHEAR FOR UP TO ANOTHER 24 HOURS. HOWEVER...A LOW-LEVEL
BAROCLINIC ZONE ASSOCIATED WITH A LARGE DEEP-LAYER TROUGH OVER THE
EASTERN U.S. IS IMPINGING ON THE CIRCULATION OF THE HURRICANE. A
DRAMATIC INCREASE IN SHEAR IS FORECAST AFTER 24 HOURS...AND
THERMODYNAMIC PARAMETERS ARE EXPECTED TO BECOME INCREASINGLY
UNFAVORABLE. WEAKENING SEEMS IMMINENT...WITH THE RATE OF WEAKENING
LIKELY INCREASING AFTER 36 HOURS...GIVEN THE EXTREME AMOUNT OF
VERTICAL WIND SHEAR DEPICTED BY THE LARGE-SCALE MODELS. THE
OFFICIAL NHC FORECAST IS SIMILAR TO THE PREVIOUS ONE BUT INDICATES
TOMAS BECOMING A REMNANT LOW SOONER.
 
THE INITIAL MOTION IS 050/13...A BIT FASTER THAN THE PREVIOUS
ESTIMATE. GLOBAL MODELS CONTINUE TO BE IN GOOD AGREEMENT WITH
RESPECT TO THE OVERALL ENVIRONMENTAL SYNOPTIC PATTERN DURING THE
NEXT SEVERAL DAYS. THE CYCLONE SHOULD MOVE NORTHEASTWARD DURING THE
NEXT 24-36 HOURS IN A DEEP LAYER OF SOUTHWESTERLY FLOW AHEAD OF A
MID- TO UPPER-LEVEL TROUGH MOVING FROM THE EASTERN U.S. INTO THE
WESTERN ATLANTIC. AFTER THAT...THE TRACK GUIDANCE DIVERGES... WITH
SEVERAL OF THE MORE RELIABLE MODELS SHOWING A HEAVILY SHEARED TOMAS
MOVING SLOWLY ON AN EASTWARD TRACK AT THE BASE OF THE WESTERN
ATLANTIC TROUGH. A SECOND CAMP OF MODELS SHOWS A DEEPER CYCLONE
BEING PULLED NORTHWARD AND BECOMING INVOLVED WITH THE BAROCLINIC
ZONE ASSOCIATED ASSOCIATED WITH THE SAME TROUGH. THE OFFICIAL
FORECAST CONTINUES TO FAVOR THE FORMER GROUP SINCE IT APPEARS
UNLIKELY THAT TOMAS WILL BE ABLE TO MANTAIN ITSELF AS A VIABLE
TROPICAL CYCLONE FOR LONG. THE NEW NHC FORECAST IS ADJUSTED TO THE
RIGHT DURING THE SHORT TERM TO ACCOUNT FOR THE CURRENT MORE
NORTHEASTERLY MOTION BUT IS SIMILAR TO THE PREVIOUS FORECAST BEYOND
48 HOURS.
 
EVEN THOUGH THE CENTER OF TOMAS HAS PASSED NORTH OF HISPANIOLA...
SOUTHERLY FLOW BEHIND TOMAS WILL RESULT IN THE CONTINUATION OF A
HEAVY RAINFALL THREAT FOR THE NEXT DAY OR TWO...WHICH
COULD PRODUCE FLASH FLOODING AND LIFE-THREATENING MUD SLIDES OVER
PORTIONS OF HAITI AND THE DOMINICAN REPUBLIC.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      06/0900Z 21.9N  71.3W    60 KT
 12HR VT     06/1800Z 23.2N  70.2W    60 KT
 24HR VT     07/0600Z 24.2N  69.4W    55 KT
 36HR VT     07/1800Z 24.7N  68.7W    50 KT
 48HR VT     08/0600Z 25.0N  67.5W    40 KT
 72HR VT     09/0600Z 25.5N  65.0W    25 KT...POST-TROP/REMNT LOW
 96HR VT     10/0600Z 26.5N  60.9W    20 KT...POST-TROP/REMNT LOW
120HR VT     11/0600Z...DISSIPATED
 
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FORECASTER KIMBERLAIN/FRANKLIN
 
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