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| #386788 (Received by flhurricane at: 10:38 PM 31.Oct.2010) TCDAT1 TROPICAL STORM TOMAS DISCUSSION NUMBER 12 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL212010 1100 PM AST SUN OCT 31 2010 RECENT MICROWAVE DATA...PARTICULARLY A 0045 UTC SSMIS PASS... INDICATE THAT THE LOW-LEVEL CENTER OF TOMAS IS NOW LOCATED ABOUT 140 N MI TO THE WEST OF THE DEEP CONVECTION AND HAS BEEN MOVING A LITTLE SOUTH OF DUE WEST. DVORAK ESTIMATES HAVE DECREASED TO T3.0/4.0 FROM TAFB...T2.5/3.5 FROM SAB...AND T3.4/4.3 FROM THE ADT...AND THE INITIAL INTENSITY IS THEREFORE LOWERED TO 55 KT FOR THIS ADVISORY. THIS INTENSITY COULD BE A LITTLE GENEROUS...BUT ADDITIONAL ADJUSTMENTS CAN BE MADE WHEN THE AIR FORCE HURRICANE HUNTER AIRCRAFT INVESTIGATES THE CYCLONE LATER TONIGHT. SIGNIFICANT MODIFICATIONS HAVE BEEN REQUIRED TO THE INTENSITY FORECAST ON THIS ADVISORY. STRONG SOUTHWESTERLY SHEAR BELOW THE OUTFLOW LAYER IS EXPECTED TO CONTINUE TO AFFECT TOMAS FOR THE NEXT 48 HOURS...AS SHOWN BY THE SHIPS GUIDANCE...AND ALL THE INTENSITY MODELS ARE SHOWING CONTINUED WEAKENING DURING THAT TIME. THE OFFICIAL FORECAST HAS BEEN ADJUSTED DOWNWARD...LEVELING THE INTENSITY AT 40 KT BETWEEN 24 AND 48 HOURS. THIS IS STILL ABOVE MOST OF THE INTENSITY GUIDANCE...AND IT IS NOT OUT OF THE QUESTION THAT TOMAS COULD WEAKEN MORE THAN INDICATED IN THE OFFICIAL FORECAST. THE SHEAR IS EXPECTED TO RELAX AFTER 72 HOURS...AND THERE WILL BE AN OPPORTUNITY FOR TOMAS TO RESTRENGTHEN...POSSIBLY BACK TO HURRICANE INTENSITY...OVER THE CENTRAL CARIBBEAN SEA. NOW THAT THE LOW- AND MID-LEVEL CIRCULATIONS OF TOMAS HAVE BECOME INCREASINGLY DECOUPLED...THE LOW-LEVEL CENTER HAS ACCELERATED OVER THE PAST FEW HOURS WITH AN INITIAL MOTION ESTIMATED TO BE 270/13. THE SOUTHWESTWARD ADJUSTMENT OF THE INITIAL POSITION HAS CAUSED THE NEW FORECAST TRACK TO BE A LITTLE SOUTH AND FASTER THAN THE PREVIOUS FORECAST. THE TRACK GUIDANCE IS IN RELATIVELY GOOD AGREEMENT ON THE FUTURE TRACK OF TOMAS...BUT THERE CONTINUES TO BE SPEED DIFFERENCES MAINLY ON DAYS 4 AND 5 WHEN A DEEP MID-LATITUDE TROUGH SWEEPS ACROSS THE GULF OF MEXICO AND NORTHWESTERN CARIBBEAN. THE GFDN AND HWRF ARE STILL THE FASTEST MODELS...BUT THEY HAVE BEEN JOINED BY THE ECMWF...MAKING A FASTER SCENARIO A LITTLE MORE CREDIBLE BY DAY 5. FORECAST POSITIONS AND MAX WINDS INITIAL 01/0300Z 14.2N 66.5W 55 KT 12HR VT 01/1200Z 14.4N 68.1W 45 KT 24HR VT 02/0000Z 14.7N 69.8W 40 KT 36HR VT 02/1200Z 14.8N 71.6W 40 KT 48HR VT 03/0000Z 14.8N 73.1W 40 KT 72HR VT 04/0000Z 15.1N 74.5W 50 KT 96HR VT 05/0000Z 16.5N 74.5W 65 KT 120HR VT 06/0000Z 20.0N 72.5W 70 KT $$ FORECASTER BERG |
