Hurricane TOMAS

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HURRICANE TOMAS DISCUSSION NUMBER  37
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL212010
1100 PM AST SAT NOV 06 2010
 
BEFORE EXITING TOMAS...THE NOAA HURRICANE HUNTER AIRCRAFT REPORTED A
700-MB FLIGHT-LEVEL WIND MAXIMUM OF 75 KT...A PEAK SFMR WIND OF 61
KT...AND A CENTRAL PRESSURE OF 987 MB. THIS SUGGESTS THAT THE
INTENSITY HAS LEVELED OFF...AND THE INITIAL INTENSITY REMAINS 70
KT. WHILE THE INITIAL SHEAR VALUES FROM SHIPS AND UW-CIMMS ARE
15-20 KT...TOMAS OBVIOUSLY HAS NOT YET FELT THE EFFECTS OF THIS
SHEAR IN THE INNER CORE. HOWEVER...WATER VAPOR IMAGERY AND GOES
CLOUD TRACK WINDS SHOW STRONG UPPER-LEVEL SOUTHERLY FLOW AND DRY
AIR INCHING CLOSER TO TOMAS...AND THE SHEAR SHOULD INCREASE
MARKEDLY IN THE NEXT 12 HOURS. IN FACT...THE SHIPS MODEL SHOWS
SHEAR VALUES OF AROUND 50 KT IN 24 HOURS. THE SHEAR...DRIER
MID-LEVEL AIR...AND COOLER WATERS SHOULD RESULT IN STEADY
WEAKENING...REDUCING TOMAS TO A REMNANT LOW IN 3 DAYS WITH
DISSIPATION EXPECTED IN ABOUT 4 DAYS. THE NEW NHC INTENSITY
FORECAST IS SIMILAR TO THE PREVIOUS ONE...AND IS CLOSEST TO THE
SHIPS MODEL AFTER 24 HOURS. 
 
SATELLITE IMAGERY SUGGESTS THAT TOMAS MAY BE SLOWING DOWN...AND THE
INITIAL MOTION ESTIMATE IS 025/9. THERE IS GOOD AGREEMENT IN THE
GUIDANCE SLOWING TOMAS EVEN FURTHER IN THE NEXT 12 HOURS. AFTER
THAT TIME...TOMAS SHOULD BE STEERED EAST-NORTHEASTWARD FOR A DAY OR
TWO BY THE DEEP-LAYER TROUGH/LOW ADVANCING INTO THE WESTERN
ATLANTIC. A TURN BACK TOWARD THE NORTHEAST IS EXPECTED IN ABOUT 72
HOURS...AS WHAT IS LEFT OF TOMAS IS PULLED NORTHWARD AHEAD OF THE
WESTERN ATLANTIC LOW. THE GFS AND ECMWF MODELS SHOW THE CIRCULATION
OF TOMAS DISSIPATING BY 96 HOURS...AND DISSIPATION IS ALSO
INDICATED BY THE SHIPS MODEL BY THAT TIME. IT IS WORTH NOTING
THAT THE UKMET MAINTAINS TOMAS AS A DEEPER CYCLONE AND TAKES IT
FARTHER NORTHWARD BEFORE MERGING IT WITH A FRONTAL ZONE. HOWEVER...
THIS SCENARIO SEEMS UNLIKELY GIVEN THAT TOMAS SHOULD HAVE DIFFICULTY
REMAINING A DEEP CYCLONE DUE TO THE SHEAR AND UNFAVORABLE
THERMODYNAMIC CONDITIONS. THE NEW NHC TRACK FORECAST IS A BLEND OF
THE PREVIOUS ADVISORY AND THE NEW MULTI-MODEL CONSENSUS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      07/0300Z 25.2N  69.6W    70 KT
 12HR VT     07/1200Z 25.8N  69.2W    60 KT
 24HR VT     08/0000Z 26.1N  68.1W    50 KT
 36HR VT     08/1200Z 26.5N  66.1W    40 KT
 48HR VT     09/0000Z 27.4N  63.2W    35 KT
 72HR VT     10/0000Z 31.0N  57.5W    25 KT...POST-TROP/REMNT LOW
 96HR VT     11/0000Z...DISSIPATED
 
$$
FORECASTER BRENNAN
 
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