000 WTNT41 KNHC 022047 TCDAT1 TROPICAL STORM TOMAS DISCUSSION NUMBER 19 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL212010 500 PM EDT TUE NOV 02 2010 AN AIR FORCE HURRICANE HUNTER AIRCRAFT INVESTIGATING TOMAS FOUND THE STORM WEAKER THAN IT WAS EARLY THIS MORNING...WITH A SOMEWHAT ELONGATED CIRCULATION. MAXIMUM FLIGHT-LEVEL AND SFMR SURFACE WINDS SUPPORT LOWERING THE INITIAL INTENSITY TO 35 KT. THE CONVECTIVE STRUCTURE OF TOMAS HAS ALSO BECOME LESS ORGANIZED. THE CONTINUED WEAKENING...OR AT LEAST LACK OF STRENGTHENING...OF TOMAS IS LIKELY DUE TO MID-LEVEL DRY AIR...SOME WESTERLY SHEAR...AND PERHAPS THE PROXIMITY TO SOUTH AMERICA. HOWEVER...INTENSIFICATION STILL SEEMS LIKELY GIVEN THE EXPECTED FAVORABLE ATMOSPHERIC ENVIRONMENT DURING THE NEXT FEW DAYS. THE OFFICIAL FORECAST HAS BEEN ADJUSTED DOWNWARD FROM THE PREVIOUS ONE FOR THE FIRST COUPLE OF DAYS...DUE TO THE LOWER INITIAL INTENSITY...BUT IS OTHERWISE SIMILAR TO THE PREVIOUS ADVISORY. AIRCRAFT AND SATELLITE FIXES INDICATE THAT TOMAS CONTINUES WESTWARD AT AROUND 12 KT. THE TRACK FORECAST REASONING IS UNCHANGED FROM EARLIER. A STRONG MID- TO UPPER-LEVEL TROUGH CURRENTLY MOVING INTO THE WESTERN GULF OF MEXICO IS EXPECTED TO SWING EASTWARD INTO THE NORTHWESTERN CARIBBEAN SEA. THIS PATTERN WILL CAUSE THE SYSTEM TO SLOW DOWN AND TURN TOWARD THE NORTH IN THE NEXT 24 TO 48 HOURS. TOMAS IS THEN FORECAST TO TRACK NORTHEASTWARD WITH SOME INCREASE IN FORWARD SPEED IN THE 2 TO 4 DAY PERIOD. BY DAY 5...MOST OF THE GLOBAL MODELS SHOW THE TROUGH FLATTENING AND LEAVING TOMAS BEHIND. THE LATEST TRACK GUIDANCE HAS SHIFTED TO THE LEFT...AND THE OFFICIAL FORECAST IS ADJUSTED IN THAT DIRECTION. 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 02/2100Z 13.5N 74.6W 35 KT 12HR VT 03/0600Z 13.8N 75.6W 40 KT 24HR VT 03/1800Z 14.2N 76.6W 50 KT 36HR VT 04/0600Z 14.7N 77.0W 60 KT 48HR VT 04/1800Z 15.3N 76.7W 70 KT 72HR VT 05/1800Z 18.1N 74.8W 85 KT 96HR VT 06/1800Z 21.0N 72.5W 75 KT 120HR VT 07/1800Z 22.5N 70.5W 60 KT $$ FORECASTER CANGIALOSI/BROWN