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| #388136 (Received by flhurricane at: 11:05 AM 06.Nov.2010) TCDAT1 TROPICAL STORM TOMAS DISCUSSION NUMBER 34 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL212010 1100 AM EDT SAT NOV 06 2010 A NOAA HURRICANE HUNTER AIRCRAFT REPORTED 850 MB FLIGHT-LEVEL WINDS OF 69 KT TO THE SOUTHEAST OF THE CENTER OF TOMAS...WITH SFMR WINDS OF 54 KT. THE MINIMUM CENTRAL PRESSURE HAS BEEN IN THE 990-992 MB RANGE DURING THE LAST SEVERAL FIXES. BASED ON THESE DATA...THE INITIAL INTENSITY IS NUDGED DOWNWARD TO 55 KT. THE STORM STILL HAS A SYMMETRIC BANDED CONVECTIVE PATTERN...AND A RECENT WINDSAT OVERPASS SHOWS A WELL-DEFINED LOW-LEVEL STRUCTURE. HOWEVER... COLD-AIR CLOUDS ARE PRESENT IN SATELLITE IMAGERY NEAR THE WESTERN EDGE OF CONVECTION...INDICATING THAT A COLD FRONT IS APPROACHING THE CYCLONE. THE INITIAL MOTION IS 045/14. ALL GUIDANCE INDICATES THAT TOMAS SHOULD SLOW ITS FORWARD MOTION DURING THE NEXT 24 HR AS PRESSURES RISES TO THE NORTH OF THE CYCLONE AND FALL TO THE EAST OF IT. AFTER THAT TIME...ANOTHER ROUND OF BAROCLINIC CYCLOGENESIS SHOULD OCCUR OVER THE NORTHWESTERN ATLANTIC...WITH A NEW DEEP-LAYER LOW DEVELOPING TO THE NORTH OF TOMAS. WHILE THERE ARE SIGNIFICANT DIFFERENCES IN THE DETAILS BETWEEN THE DYNAMICAL MODELS...THEY ALL FORECAST THIS NEW SYSTEM TO TURN TOMAS EASTWARD. THERE REMAINS A LARGE AMOUNT OF SPREAD IN THE TRACK GUIDANCE AFTER 48 HR...AS THE GFS/ECMWF FAVORING A SLOWER MOTION AT LOWER LATITUDE...WHILE GFDL/HWRF/NOGAPS/UKMET/GFS ENSEMBLE MEAN NOW FAVOR A FASTER MOTION AT HIGHER LATITUDE. THE NEW FORECAST TRACK IS A BLEND OF THESE EXTREMES IN BOTH DIRECTION AND SPEED...AND IS SLOWER THAN THE CONSENSUS MODELS. THE NEW TRACK IS SHIFTED A LITTLE TO THE WEST OF THE PREVIOUS FORECAST DURING THE FIRST 24 HR...AND A LITTLE TO THE NORTH THEREAFTER. TOMAS HAS BEEN SLOWLY WEAKENING EVEN THOUGH THE VERTICAL WIND SHEAR REMAINS LIGHT AND THE SEA SURFACE TEMPERATURES WARM. BASED ON THIS...LITTLE CHANGE IN STRENGTH IS FORECAST DURING THE FIRST 24 HR OF THE FORECAST. HOWEVER...GIVEN THE STRUCTURE...THERE IS STILL SOME CHANCE OF RE-INTENSIFICATION DURING THIS TIME. TOMAS SHOULD ENCOUNTER SIGNIFICANT AMOUNTS OF COOLER/DRIER AIR AND INCREASING WIND SHEAR AFTER 24 HR...WHICH SHOULD CAUSE A STEADY AND POSSIBLY RAPID WEAKENING. THE LATTER PART OF THE NEW INTENSITY FORECAST CALLS FOR THE CYCLONE TO DEGENERATE INTO A REMNANT LOW BY 72 HR AND TO DISSIPATE COMPLETELY BY 120 HR. THERE IS A POSSIBILITY TOMAS COULD UNDERGO EXTRATROPICAL TRANSITION INSTEAD OF DEGENERATION...ESPECIALLY IF IT TAKES A MORE NORTHERLY COURSE AND INTERACTS WITH THE WESTERN ATLANTIC BAROCLINIC LOW. TOMAS IS NOW FAR ENOUGH TO THE NORTH AND EAST THAT THE THREAT OF WIDESPREAD HEAVY RAINS HAS DIMINISHED OVER HAITI AND THE DOMINICAN REPUBLIC. FORECAST POSITIONS AND MAX WINDS INITIAL 06/1500Z 23.1N 70.6W 55 KT 12HR VT 07/0000Z 24.1N 69.9W 55 KT 24HR VT 07/1200Z 24.8N 69.3W 55 KT 36HR VT 08/0000Z 25.1N 68.5W 50 KT 48HR VT 08/1200Z 25.4N 66.5W 40 KT 72HR VT 09/1200Z 26.5N 62.5W 25 KT...POST-TROP/REMNT LOW 96HR VT 10/1200Z 28.0N 58.0W 20 KT...POST-TROP/REMNT LOW 120HR VT 11/1200Z...DISSIPATED $$ FORECASTER BEVEN |
