000 WTNT44 KNHC 242037 TCDAT4 TROPICAL STORM NADINE DISCUSSION NUMBER 49 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142012 500 PM AST MON SEP 24 2012 BURSTS OF CONVECTION HAVE CONTINUED TO DEVELOP OVER THE NORTHWESTERN PORTION OF NADINE TODAY...AND THERE ARE SOME LOOSE CONVECTIVE BANDS. HOWEVER...DVORAK T-NUMBERS CONTINUE TO UNDERESTIMATE THE WINDS THAT HAVE BEEN OBSERVED IN RECENT SCATTEROMETER PASSES. THE MOST CURRENT SCATTEROMETER PASS FROM THE OCEANSAT-2 SATELLITE INDICATED SIMILAR PEAK WINDS AS IN THE MORNING ASCAT PASS. THEREFORE... THE INITIAL WIND SPEED REMAINS 45 KT. THE INTENSITY FORECAST REASONING IS UNCHANGED FROM THIS MORNING. NADINE IS EXPECTED TO REMAIN IN A MARGINAL ENVIRONMENT DURING THE NEXT DAY OR SO. AFTER THAT TIME...THE STORM IS FORECAST TO MOVE OVER A LITTLE WARMER WATER AND INTO AN AREA OF SLIGHTLY LESS VERTICAL SHEAR...SO MODEST STRENGTHENING IS INDICATED. LATER IN THE PERIOD...STRONGER UPPER-LEVEL WESTERLIES ARE EXPECTED TO CAUSE AN INCREASE IN SHEAR AND THIS SHOULD HALT ANY ADDITIONAL INCREASE IN WIND SPEED. NADINE APPEARS TO BE TURNING WESTWARD WITH AN INITIAL MOTION OF 280/6. THE CYCLONE SHOULD TURN WEST-SOUTHWESTWARD IN A DAY OR SO AS IT MOVES AROUND THE SOUTHEASTERN PORTION OF A LARGE BLOCKING RIDGE OVER THE CENTRAL ATLANTIC. THE TRACK MODELS HAVE SHIFTED SIGNIFICANTLY SOUTHWARD THIS CYCLE WITH MOST OF THE GUIDANCE TAKING NADINE ALMOST DUE SOUTHWARD FOR A PERIOD OF TIME AS IT COMES UNDER THE INFLUENCE OF AN AREA OF STRENGTHENING NORTHERLY MID-LEVEL FLOW BETWEEN A DEEPENING TROUGH OVER THE EASTERN ATLANTIC AND THE AFOREMENTIONED RIDGE. AFTER 72 HOURS...THE RIDGE IS FORECAST TO MOVE EASTWARD WHICH SHOULD ALLOW A SLOW WEST-NORTHWESTWARD OR NORTHWESTWARD MOTION TO BEGIN. THE TRACK GUIDANCE HAS ONCE AGAIN TRENDED TOWARD A SLOWER MOTION NEAR THE END FORECAST PERIOD...THUS THE NHC FORECAST IS SLOWER AND SOUTH OF THE PREVIOUS TRACK... ESPECIALLY AT DAYS 4 AND 5. FORECAST POSITIONS AND MAX WINDS INIT 24/2100Z 31.7N 28.6W 45 KT 50 MPH 12H 25/0600Z 31.7N 29.7W 45 KT 50 MPH 24H 25/1800Z 31.4N 30.6W 45 KT 50 MPH 36H 26/0600Z 30.7N 30.9W 50 KT 60 MPH 48H 26/1800Z 29.8N 30.9W 55 KT 65 MPH 72H 27/1800Z 28.7N 32.0W 60 KT 70 MPH 96H 28/1800Z 29.0N 33.0W 60 KT 70 MPH 120H 29/1800Z 30.0N 34.5W 55 KT 65 MPH $$ FORECASTER BROWN