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#547427 (Received by flhurricane at: 4:41 AM 03.Oct.2012) TCDAT4 TROPICAL STORM NADINE DISCUSSION NUMBER 83 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142012 500 AM AST WED OCT 03 2012 NADINE IS SHOWING A SHEARED CLOUD PATTERN THIS MORNING...WITH THE LOW-LEVEL CENTER PARTLY EXPOSED AT THE NORTHWESTERN EDGE OF THE CENTRAL CONVECTION DUE TO 20-30 KT OF NORTHERLY VERTICAL WIND SHEAR. THE INITIAL INTENSITY REMAINS 45 KT BASED ON A BLEND OF SATELLITE T-NUMBERS AND CI-NUMBERS FROM TAFB AND SAB. NADINE IS GRADUALLY TURNING TO THE LEFT...WITH THE INITIAL MOTION NOW 075/9. SATELLITE IMAGERY SHOWS A LARGE DEEP-LAYER LOW AND ASSOCIATED SURFACE COLD FRONT APPROACHING NADINE FROM THE NORTHWEST. THIS SYSTEM SHOULD CAUSE THE MUCH SMALLER NADINE TO ACCELERATE NORTHEASTWARD AND THEN NORTH-NORTHEASTWARD OVER THE NEXT 48 HR...AND DURING THIS TIME THE FORECAST TRACK IS NEAR THE CENTER OF THE TRACK GUIDANCE ENVELOPE. THE GUIDANCE BECOMES DIVERGENT BETWEEN 48-72 HR...WITH THE GFS-BASED GUIDANCE NOW FORECASTING A NORTHEASTWARD MOTION...WHILE THE ECMWF AND UKMET CALL FOR NADINE TO TURN WESTWARD ON THE NORTH SIDE OF THE LOW. THIS PART OF THE TRACK FORECAST FOLLOWS THE ECMWF AND UKMET IN AGREEMENT WITH THE PREVIOUS FORECAST AND GUIDANCE FROM THE OCEAN PREDICTION CENTER. NADINE SHOULD ENCOUNTER INCREASING SHEAR AND DECREASING SEA SURFACE TEMPERATURES DURING THE NEXT 24-36 HR. THE INTENSITY FORECAST CALLS FOR LITTLE CHANGE IN STRENGTH BEFORE THE STORM REACHES THE AZORES...BUT IT WOULD NOT BE SURPRISING IF SOME WEAKENING OCCURRED. THE CYCLONE SHOULD MERGE WITH THE APPROACHING FRONT AND BECOME EXTRATROPICAL IN ABOUT 48 HR...WITH THE SYSTEM BECOMING ABSORBED WITHIN THE LARGE DEEP-LAYER LOW AFTER 72 HR. THE FORECAST WIND RADII HAVE BEEN REVISED BASED ON INPUT FROM THE OCEAN PREDICTION CENTER. FORECAST POSITIONS AND MAX WINDS INIT 03/0900Z 34.9N 34.6W 45 KT 50 MPH 12H 03/1800Z 35.8N 32.6W 45 KT 50 MPH 24H 04/0600Z 38.7N 29.6W 45 KT 50 MPH 36H 04/1800Z 42.7N 27.2W 45 KT 50 MPH 48H 05/0600Z 46.8N 25.9W 40 KT 45 MPH...POST-TROP/EXTRATROP 72H 06/0600Z 48.0N 29.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 96H 07/0600Z...ABSORBED BY EXTRATROPICAL LOW $$ FORECASTER BEVEN |