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#646614 (Received by flhurricane at: 3:39 AM 21.Nov.2013) TCDAT4 TROPICAL STORM MELISSA DISCUSSION NUMBER 12 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142013 500 AM AST THU NOV 21 2013 EVEN THOUGH MELISSA IS CURRENTLY OVER QUITE COOL 21 C SEA SURFACE TEMPERATURES...THE STORM IS STILL PRODUCING DEEP CONVECTION AND IS HOLDING ON TO TROPICAL CYCLONE STATUS. THE MAIN REASONS THE STORM IS ABLE TO REMAIN TROPICAL OVER THE COOL WATER IS BECAUSE OF THE COMBINED FACTORS OF A COLD AIRMASS ALOFT AND FAIRLY LOW WIND SHEAR. THE CLOUD PATTERN STILL CONSISTS OF FRAGMENTED CURVED BANDS MAINLY CONFINED TO THE WESTERN PORTION OF THE CIRCULATION...AND THE DVORAK CLASSIFICATIONS STILL SUPPORT AN INTENSITY OF 45 KT. MOST OF THE MODELS SHOW MELISSA CHANGING LITTLE IN STRENGTH OVER THE NEXT COUPLE OF DAYS...BUT THE SYSTEM WILL LIKELY BE LOSING ITS TROPICAL CHARACTERISTICS DURING THE NEXT 12 TO 24 HOURS WHILE IT MOVES OVER SEA SURFACE TEMPERATURES LOWER THAN 20 C. AFTER THE CYCLONE BECOMES POST-TROPICAL...A GRADUAL WEAKENING IS PREDICTED WITH DISSIPATION EXPECTED IN 3 TO 4 DAYS. MELISSA CONTINUES TO RACE EAST-NORTHEASTWARD AT 28 KT EMBEDDED IN THE STRONG MID-LATITUDE FLOW TO THE SOUTHEAST OF A LARGE EXTRATROPICAL CYCLONE. A DECREASE IN FORWARD SPEED AND A TURN TO THE EAST AND THEN SOUTHEAST ARE EXPECTED OVER THE NEXT FEW DAYS. THE NHC FORECAST IS AGAIN ADJUSTED SOUTHWARD...FOLLOWING THE LATEST TREND IN THE GUIDANCE. GALE-FORCE WINDS ARE EXPECTED TO SPREAD ACROSS THE WESTERN AND CENTRAL AZORES LATE TODAY OR TONIGHT AFTER MELISSA LOSES TROPICAL CHARACTERISTICS. FORECAST POSITIONS AND MAX WINDS INIT 21/0900Z 39.1N 38.5W 45 KT 50 MPH 12H 21/1800Z 40.2N 33.6W 45 KT 50 MPH 24H 22/0600Z 41.5N 27.7W 45 KT 50 MPH...POST-TROPICAL 36H 22/1800Z 42.2N 22.8W 45 KT 50 MPH...POST-TROP/EXTRATROP 48H 23/0600Z 42.2N 19.8W 40 KT 45 MPH...POST-TROP/EXTRATROP 72H 24/0600Z 40.0N 16.5W 30 KT 35 MPH...POST-TROP/EXTRATROP 96H 25/0600Z...DISSIPATED $$ FORECASTER CANGIALOSI |