000 WTNT41 KNHC 310246 TCDAT1 HURRICANE TOMAS DISCUSSION NUMBER 8 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL212010 1100 PM AST SAT OCT 30 2010 THE STRUCTURE OF TOMAS HAS CHANGED LITTLE SINCE THE TIME THE ST. LUCIA WEATHER SERVICE REPORTED SUSTAINED WINDS ON THAT ISLAND OF AT LEAST 80 KT AROUND 2130 UTC. AN EYE HAS NOT BECOME ESTABLISHED ON INFRARED SATELLITE IMAGERY...ALTHOUGH IT IS WELL DEFINED IN RADAR DATA FROM MARTINIQUE. THE INITIAL INTENSITY IS KEPT AT 80 KT SINCE THERE ARE NO OBVIOUS RECENT CHANGES...BUT IT IS POSSIBLE THIS COULD BE A BIT CONSERVATIVE. AN AIR FORCE HURRICANE HUNTER AIRCRAFT IS SCHEDULED TO INVESTIGATE TOMAS LATER TONIGHT. THE INITIAL MOTION IS 285/8. THE CYCLONE IS EXPECTED TO GRADUALLY GAIN LATITUDE FOR THE NEXT 48 HOURS OR SO DUE TO A MID- TO UPPER-LEVEL TROUGH THAT IS CURRENTLY LOCATED OVER THE SOUTHWEST ATLANTIC. THE TRACK GUIDANCE IS IN GENERALLY GOOD AGREEMENT ON THIS SOLUTION...BUT THERE IS MUCH GREATER SPREAD AFTER 48 HOURS. THE GFS...ECMWF...UKMET...AND GFDL SUPPORT A STRONGER MID-LEVEL RIDGE OVER THE GREATER ANTILLES AND MOVE TOMAS ON A WESTWARD OR JUST SOUTH OF WESTWARD MOTION ON DAYS 2-4. THE NOGAPS AND GFDN SHOW TOMAS MOVING WELL NORTH OF HISPANIOLA BY DAY 5...AND THE HWRF SHOWS THE CYCLONE STALLING OVER THE EASTERN CARIBBEAN SEA. THE LATTER THREE MODELS APPEAR TO BE OUTLIERS. THE NEW OFFICIAL FORECAST IS JUST A LITTLE SOUTH OF THE PREVIOUS FORECAST TO COME INTO BETTER AGREEMENT WITH THE CONSENSUS OF THE MORE SOUTHERN BATCH OF MODELS. THERE CONTINUES TO BE LOW CONFIDENCE IN THE INTENSITY FORECAST. NONE OF THE INTENSITY MODELS SHOW MUCH STRENGTHENING BEYOND ABOUT 90 KT. THE 200-MB FLOW OVER THE CARIBBEAN SEA SHOULD BE FAVORABLE FOR STRENGTHENING...ESPECIALLY IF TOMAS MAINTAINS A MORE SOUTHERN COURSE. HOWEVER...CROSS-SECTION ANALYSES OF THE GUIDANCE DOES INDICATE THAT THE CYCLONE VORTEX COULD BECOME A LITTLE TILTED OVER THE NEXT 48 HOURS OR SO...POSSIBLY DUE TO SHEAR BELOW THE OUTFLOW LAYER. BECAUSE OF THESE MIXED SIGNALS...THE OFFICIAL INTENSITY FORECAST ONLY SHOWS MODEST STRENGTHENING THROUGH 24 HOURS AND ESSENTIALLY HOLDS THE INTENSITY FAIRLY STEADY THEREAFTER. FORECAST POSITIONS AND MAX WINDS INITIAL 31/0300Z 13.6N 62.1W 80 KT 12HR VT 31/1200Z 14.0N 63.8W 90 KT 24HR VT 01/0000Z 14.6N 65.9W 95 KT 36HR VT 01/1200Z 14.9N 68.0W 95 KT 48HR VT 02/0000Z 15.0N 69.7W 95 KT 72HR VT 03/0000Z 15.0N 72.5W 95 KT 96HR VT 04/0000Z 15.5N 74.0W 100 KT 120HR VT 05/0000Z 16.0N 74.5W 100 KT $$ FORECASTER BERG/FRANKLIN