ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM TROPICAL STORM NADINE DISCUSSION NUMBER 5 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142012 1100 AM AST WED SEP 12 2012 THE SATELLITE PRESENTATION OF NADINE SHOWS A CONTINUED INCREASE IN ORGANIZATION...WITH A DEVELOPING CENTRAL DENSE OVERCAST AND CONVECTIVE BANDING FEATURES IN ALL QUADRANTS. DVORAK INTENSITY ESTIMATES ARE 55 KT FROM SAB AND 45 KT FROM TAFB. USING A BLEND OF THESE INTENSITY ESTIMATES...THE INITIAL INTENSITY IS SET TO 50 KT. ANIMATION OF WATER VAPOR IMAGERY SHOWS WEAK SHEAR OVER NADINE WITH A WELL-DEFINED UPPER-LEVEL OUTFLOW PATTERN. A BROAD TROUGH WELL TO THE NORTHEAST OF THE STORM MAY BE ASSISTING THE OUTFLOW TO THE NORTH AND EAST. NADINE IS EXPECTED TO REMAIN IN A FAVORABLE UPPER- LEVEL WIND ENVIRONMENT FOR THE NEXT COUPLE OF DAYS. HOWEVER...FROM 72 HOURS AND BEYOND NADINE IS EXPECTED TO ENCOUNTER A BELT OF STRONG WESTERLIES TO THE NORTH OF THE SUBTROPICAL RIDGE...AND THE LGEM GUIDANCE SHOWS WESTERLY SHEAR INCREASING TO 25-30 KT DURING THIS TIME FRAME. THE NHC INTENSITY FORECAST IS IN REASONABLE AGREEMENT WITH THE LATEST LGEM AND CONSENSUS MODEL GUIDANCE. IT SHOULD BE NOTED THAT THE SHIPS RI INDEX IS STILL SHOWING A SIGNIFICANT PROBABILITY OF RAPID INTENSIFICATION DURING THE NEXT 24 HOURS...SO THE OFFICIAL INTENSITY FORECAST FOR THE NEXT DAY OR TWO COULD BE CONSERVATIVE. CENTER FIXES SHOW A MOTION BETWEEN WEST-NORTHWEST AND NORTHWEST... AND THE CURRENT MOTION ESTIMATE IS 300/13. NADINE CONTINUES TO HEAD TOWARD A BREAK IN THE SUBTROPICAL RIDGE CAUSED BY A MID- TO UPPER-LEVEL LOW TO ITS WEST. THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ONE AND TAKES THE TROPICAL CYCLONE AROUND THE WESTERN PERIPHERY OF A SUBTROPICAL ANTICYCLONE FOR THE NEXT 2-3 DAYS. NADINE IS EXPECTED TO MOVE INTO THE WESTERLIES BEYOND 72 HOURS...SO THE OFFICIAL FORECAST SHOWS A TURN TOWARDS THE NORTHEAST AND EAST-NORTHEAST DURING THE LATTER PART OF THE FORECAST PERIOD. THE CURRENT NHC TRACK LIES BETWEEN THE SLOWER ECMWF...AND ITS ENSEMBLE MEAN...AND THE QUICKER 0600 UTC GFS SOLUTION. THE WIND RADII HAVE BEEN ADJUSTED BASED ON A 1215 UTC ASCAT OVERPASS...WHICH SAMPLED THE EASTERN SIDE OF THE CIRCULATION AND REVEALED A LARGER TROPICAL CYCLONE THAN PREVIOUSLY ESTIMATED. FORECAST POSITIONS AND MAX WINDS INIT 12/1500Z 19.1N 47.6W 50 KT 60 MPH 12H 13/0000Z 20.3N 49.2W 60 KT 70 MPH 24H 13/1200Z 22.1N 51.3W 70 KT 80 MPH 36H 14/0000Z 24.1N 52.9W 75 KT 85 MPH 48H 14/1200Z 26.3N 53.8W 75 KT 85 MPH 72H 15/1200Z 30.0N 52.5W 75 KT 85 MPH 96H 16/1200Z 32.5N 49.0W 70 KT 80 MPH 120H 17/1200Z 34.5N 43.5W 65 KT 75 MPH $$ FORECASTER ROTH/PASCH NNNN
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Page last modified: Monday, 31-Dec-2012 12:09:44 UTC