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#386962 (Received by flhurricane at: 4:49 PM 01.Nov.2010) TCDAT1 TROPICAL STORM TOMAS DISCUSSION NUMBER 15 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL212010 500 PM AST MON NOV 01 2010 ALTHOUGH DEEP CONVECTION HAS INCREASED NEAR THE CENTER OF TOMAS TODAY...IT IS POORLY ORGANIZED AND LACKS BANDING. VISIBLE SATELLITE IMAGES SHOW A SERIES OF ARC CLOUDS PROPAGATING AWAY FROM THE CONVECTIVE MASS...INDICATIVE OF DRY AIR NEAR THE CORE. AN ASCAT PASS AROUND 1400 UTC SHOWED MAXIMUM WINDS IN THE 30-35 KT RANGE. SINCE CONVECTION HAS INCREASED SINCE THAT TIME...THE INITIAL INTENSITY IS HELD AT 40 KT...IN AGREEMENT WITH SATELLITE INTENSITY ESTIMATES. TOMAS IS STILL MOVING A LITTLE SOUTH OF DUE WEST...AND THE INITIAL MOTION ESTIMATE IS 260/10. THE STORM IS EXPECTED TO MOVE GENERALLY WESTWARD FOR THE NEXT DAY OR SO WITHIN EASTERLY FLOW TO THE SOUTH OF A LOW- TO MID-LEVEL RIDGE. GLOBAL MODELS REMAIN IN GOOD AGREEMENT IN SHOWING A STRONG DEEP-LAYER TROUGH MOVING ACROSS THE GULF OF MEXICO AND INTO THE NORTHWESTERN CARIBBEAN BY MID TO LATE WEEK. THIS SYNOPTIC PATTERN SHOULD CAUSE THE CYCLONE TO SLOW DOWN AND THEN MAKE A TURN TOWARD THE NORTH IN ABOUT 3 DAYS. THEREAFTER... A NORTHEASTWARD MOTION WITH AN INCREASE IN FORWARD SPEED IS FORECAST AS TOMAS BECOMES EMBEDDED IN SOUTHWESTERLY FLOW TO THE EAST OF THE TROUGH. THE LATEST GUIDANCE HAS SHIFTED TO THE LEFT ONCE AGAIN THROUGH 72 HOURS....AND THE OFFICIAL FORECAST IS ADJUSTED IN THAT DIRECTION. THE NEW TRACK FORECAST IS NEAR A BLEND OF THE GFS AND ECMWF MODELS. DRY MID-LEVEL AIR AND SOUTHWESTERLY SHEAR CONTINUE TO IMPACT THE CYCLONE. THE STORM IS EXPECTED TO REMAIN IN THIS UNFAVORABLE ENVIRONMENT FOR ANOTHER 12-24 HOURS...WHICH SHOULD PREVENT MUCH STRENGTHENING. AFTER THAT TIME...ENVIRONMENTAL WINDS ARE ANTICIPATED TO BECOME MORE CONDUCIVE AND MODEL CROSS SECTIONS SUGGEST THAT THE ATMOSPHERE WILL MOISTEN. THIS ENVIRONMENT SHOULD ALLOW THE STORM TO GAIN STRENGTH...AND THE OFFICIAL FORECAST HAS BEEN ADJUSTED UPWARD TO BE IN AGREEMENT WITH THE SHIPS MODEL. FORECAST POSITIONS AND MAX WINDS INITIAL 01/2100Z 13.4N 69.7W 40 KT 12HR VT 02/0600Z 13.4N 71.2W 40 KT 24HR VT 02/1800Z 13.7N 73.0W 45 KT 36HR VT 03/0600Z 14.0N 74.2W 50 KT 48HR VT 03/1800Z 14.3N 74.9W 55 KT 72HR VT 04/1800Z 15.1N 75.0W 65 KT 96HR VT 05/1800Z 18.0N 73.5W 80 KT 120HR VT 06/1800Z 21.0N 71.0W 70 KT $$ FORECASTER CANGIALOSI |