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#646397 (Received by flhurricane at: 3:39 AM 20.Nov.2013) TCDAT4 SUBTROPICAL STORM MELISSA DISCUSSION NUMBER 8 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142013 500 AM AST WED NOV 20 2013 A SMALL AREA OF DEEP CONVECTION HAS BEEN PERSISTING NEAR AND TO THE NORTH OF THE CENTER OF MELISSA SINCE ABOUT 0400 UTC. THIS SUGGESTS THAT MELISSA COULD BE NEARING THE EXPECTED TRANSITION FROM A SUBTROPICAL TO A TROPICAL STORM. NONETHELESS...THE STRENGTH OF THE CYCLONE HAS NOT CHANGED...BASED ON A SATELLITE INTENSITY ESTIMATE FROM TAFB AND EARLIER ASCAT DATA. THE ENVIRONMENTAL CONDITIONS ARE NOT CONDUCIVE FOR STRENGTHENING...AS MELISSA IS EXPECTED TO MOVE OVER PROGRESSIVELY COLDER WATER AND REMAIN IN AT LEAST MODERATE SOUTH-SOUTHWESTERLY SHEAR. THEREFORE...THE NHC FORECAST CALLS FOR LITTLE CHANGE IN INTENSITY DURING THE NEXT FEW DAYS...FOLLOWING THE GFS AND ECMWF GUIDANCE. POST-TROPICAL TRANSITION IS EXPECTED TO OCCUR IN 24 TO 36 HOURS...WHEN THE CYCLONE IS FORECAST TO BE OVER SEA SURFACE TEMPERATURES BELOW 20C. MELISSA IS ACCELERATING TO THE NORTHEAST...AND THE LATEST INITIAL MOTION ESTIMATE IS 055/20. A CONTINUED FAST NORTHEASTWARD TO EAST-NORTHEASTWARD MOTION IS EXPECTED DURING THE NEXT COUPLE OF DAYS WHILE MELISSA REMAINS EMBEDDED IN THE STRONG FLOW TO THE SOUTHEAST OF A LARGE EXTRATROPICAL CYCLONE. DISSIPATION IS NOW PREDICTED TO OCCUR IN 4 DAYS...IN AGREEMENT WITH MOST OF THE GLOBAL MODEL GUIDANCE. FORECAST POSITIONS AND MAX WINDS INIT 20/0900Z 34.8N 50.2W 45 KT 50 MPH 12H 20/1800Z 36.8N 46.4W 45 KT 50 MPH 24H 21/0600Z 39.3N 40.2W 45 KT 50 MPH 36H 21/1800Z 41.4N 34.0W 45 KT 50 MPH...POST-TROPICAL 48H 22/0600Z 43.0N 28.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 72H 23/0600Z 45.0N 22.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 96H 24/0600Z...DISSIPATED $$ FORECASTER CANGIALOSI |