000 WTNT41 KNHC 030242 TCDAT1 TROPICAL STORM TOMAS DISCUSSION NUMBER 20 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL212010 1100 PM EDT TUE NOV 02 2010 SATELLITE IMAGES INDICATE THAT OVERALL CONVECTION HAS DECREASED DURING THE PAST SEVERAL HOURS...THOUGH A CURVED BAND HAS BECOME A LITTLE BETTER-DEFINED RECENTLY. MICROWAVE DATA SUGGEST THE CENTER IS ON THE SOUTHEASTERN SIDE OF THAT BAND...AND REMNANTS OF THE OLD MID-LEVEL CIRCULATION CAN BE SEEN NORTHWEST OF ARUBA. SATELLITE INTENSITY ESTIMATES VARY FROM 35-55 KT...AND NO CHANGE WILL BE MADE TO THE INITIAL WIND SPEED OF 35 KT. AN AIR FORCE HURRICANE HUNTER WILL BE IN THE AREA IN A FEW HOURS TO CHECK ON THE STATUS OF TOMAS. LARGE-SCALE ENVIRONMENTAL PARAMETERS APPEAR TO BE RATHER FAVORABLE FOR FUTURE INTENSIFICATION WITH LOW SHEAR AND VERY WARM WATER FOR THE NEXT FEW DAYS. IT IS UNCERTAIN...HOWEVER...IF TOMAS CAN TAKE ADVANTAGE OF THESE CONDITIONS. A LOOK AT GLOBAL MODEL CROSS- SECTIONS SHOW A TILTED VORTEX INITIALLY...WITH THE GFS/UKMET SUGGESTING A MORE FAVORABLE VERTICAL VORTEX STRUCTURE FOR STRENGTHENING IN A DAY OR TWO. THE ECMWF MODEL...WHICH WAS ONE OF THE FEW MODELS THAT PREDICTED THE WEAKENING OF TOMAS IN THE EASTERN CARIBBEAN...HAS A QUITE DIFFERENT SCENARIO WITH A GOOD DEAL OF TILT REMAINING FOR THE NEXT FEW DAYS AND ONLY A MODEST INCREASE IN WINDS UNTIL AFTER THE TROPICAL CYCLONE LEAVES THE CARIBBEAN. WITH SUCH DIVERGENCE IN THE GUIDANCE...THE NEW FORECAST IS ABOUT THE SAME THE PREVIOUS ONE...A LITTLE HIGHER THAN THE MODEL CONSENSUS. AN UNCERTAIN INITIAL MOTION ESTIMATE IS 280/7. A CONTINUED SLOW-DOWN OF THE TROPICAL CYCLONE IS LIKELY AS RIDGING WEAKENS TO THE NORTH OF TOMAS. A DEEP LAYER LOW ENTERING THE GULF OF MEXICO IS EXPECTED TO ACCELERATE AND TURN TOMAS TO THE NORTH AND NORTHEAST ON THURSDAY. WHILE THE MODELS TAKE VARIOUS SPEEDS AND ROUTES TO GET THERE...THEY REMAIN FOCUSED IN THE DIRECTION OF SOUTHWESTERN HAITI. THE NHC FORECAST IS ADJUSTED SLIGHTLY TO THE RIGHT OF THE PREVIOUS FORECAST DURING THE FIRST COUPLE OF DAYS...AND GENERALLY LIES TO THE SOUTHEAST OF THE MODEL CONSENSUS. THE HWRF AND GFDN HAVE A RATHER DEEP AND INTENSE CIRCULATION...WHICH APPEAR TO BE OUTLIERS AND BIASING TVCN...THE VARIABLE CONSENSUS MODEL...TOO FAR TO THE NORTH. REGARDLESS OF THE EXACT TRACK AND INTENSITY OF TOMAS...IT APPEARS THAT THE TROPICAL CYCLONE WILL POSE A SIGNIFICANT THREAT OF HEAVY RAINFALL OVER HAITI AND THE DOMINICAN REPUBLIC LATER IN THE WEEK. FORECAST POSITIONS AND MAX WINDS INITIAL 03/0300Z 13.7N 75.1W 35 KT 12HR VT 03/1200Z 14.0N 75.9W 40 KT 24HR VT 04/0000Z 14.4N 76.5W 50 KT 36HR VT 04/1200Z 15.0N 76.6W 60 KT 48HR VT 05/0000Z 16.0N 76.0W 70 KT 72HR VT 06/0000Z 19.0N 73.9W 80 KT 96HR VT 07/0000Z 22.0N 71.5W 70 KT 120HR VT 08/0000Z 22.5N 69.5W 60 KT $$ FORECASTER BLAKE