000 WTNT41 KNHC 311444 TCDAT1 HURRICANE TOMAS DISCUSSION NUMBER 10 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL212010 1100 AM AST SUN OCT 31 2010 DEEP CONVECTION ASSOCIATED WITH TOMAS HAS GENERALLY DECREASED DURING THE LAST FEW HOURS AND BANDING FEATURES HAVE BECOME A LITTLE LESS ORGANIZED. IN ADDITION...RECENT MICROWAVE IMAGES NO LONGER SHOW AN EYE. BASED ON THIS...THE INITIAL WIND SPEED IS LOWERED TO 80 KT...WHICH IS A BLEND OF THE LATEST SUBJECTIVE AND OBJECTIVE SATELLITE INTENSITY ESTIMATES. THE NEXT AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT SHOULD PROVIDE A BETTER ASSESSMENT OF THE INTENSITY EARLY THIS AFTERNOON. THE INITIAL MOTION ESTIMATE IS 285/8. A GENERAL WESTWARD TO WEST-NORTHWESTWARD MOTION AT ABOUT THE SAME SPEED IS EXPECTED DURING THE NEXT COUPLE OF DAYS AS MID-LEVEL RIDGING REMAINS IN PLACE TO THE NORTH OF TOMAS. SOME OF THE MODELS EVEN SHOW A SOUTH OF WEST MOTION DURING THAT TIME. IN ABOUT 3 DAYS...THE CYCLONE IS EXPECTED TO SLOW DOWN AS A LARGE MID- TO UPPER-LEVEL LOW MOVES OVER THE GULF OF MEXICO...CAUSING THE RIDGE TO ERODE. TOMAS IS FORECAST TO GRADUALLY TURN TOWARD THE NORTH IN 4 TO 5 DAYS AS IT FEELS THE INFLUENCE OF SOUTHERLY FLOW TO THE EAST OF THE TROUGH. THE LATEST MODEL GUIDANCE HAS CHANGED LITTLE FROM THE LAST CYCLE...AND THE OFFICIAL FORECAST IS ESSENTIALLY AN UPDATE OF THE PREVIOUS TRACK. ALTHOUGH TOMAS LIES OVER AN AREA OF HIGH OCEANIC HEAT CONTENT... MODERATE SOUTHWESTERLY SHEAR AND SOME MID-LEVEL DRY AIR AS SHOWN BY MODEL CROSS SECTIONS COULD BE A LIMITING FACTOR FOR INTENSIFICATION DURING THE NEXT COUPLE OF DAYS. IN FACT...SEVERAL OF THE RELIABLE MODELS...INCLUDING THE GFS...ECMWF...AND GFDL...SHOW THE VORTEX TILTING TO THE NORTHEAST WITH HEIGHT. THIS RESULTS IN THE WEAKENING OF THE HURRICANE IN THOSE MODELS DURING THE NEXT COUPLE OF DAYS. THE OFFICIAL FORECAST HAS BEEN NUDGED DOWNWARD THROUGH 48 HOURS BUT REMAINS HIGHER THAN ALL OF THE INTENSITY GUIDANCE DURING THAT TIME. A MORE FAVORABLE UPPER-LEVEL WIND PATTERN IS EXPECTED DURING THE 3 TO 5 DAY TIME FRAME...AND THAT SHOULD ALLOW FOR STEADY STRENGTHENING. ALTHOUGH TROPICAL STORM WARNINGS FOR THE WINDWARD ISLANDS HAVE BEEN DISCONTINUED...THE THREAT OF HEAVY RAINFALL IS EXPECTED TO CONTINUE OVER MUCH OF THE LESSER ANTILLES THROUGH TONIGHT. FORECAST POSITIONS AND MAX WINDS INITIAL 31/1500Z 14.0N 63.7W 80 KT 12HR VT 01/0000Z 14.5N 65.1W 75 KT 24HR VT 01/1200Z 14.9N 67.2W 75 KT 36HR VT 02/0000Z 15.0N 69.1W 75 KT 48HR VT 02/1200Z 15.0N 70.6W 75 KT 72HR VT 03/1200Z 15.0N 72.5W 85 KT 96HR VT 04/1200Z 15.5N 73.5W 95 KT 120HR VT 05/1200Z 17.0N 73.5W 100 KT $$ FORECASTER CANGIALOSI/BROWN