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#545445 (Received by flhurricane at: 1:35 PM 25.Sep.2012) TCDAT4 TROPICAL STORM NADINE DISCUSSION NUMBER 52 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142012 1100 AM AST TUE SEP 25 2012 NADINE HAS A CLOUD FREE REGION NEAR THE CENTER IN INFRARED SATELLITE IMAGERY...HOWEVER THE CONVECTION IN THE SURROUNDING RING IS NOT VERY DEEP. THIS YIELDS DVORAK ESTIMATES THAT STILL SEEM TO BE UNDERESTIMATING THE INTENSITY OF NADINE. THE INITIAL WIND SPEED REMAINS 40 KT...WHICH IS A BLEND OF THE MOST RECENT UW/CIMMS AMSU AND ADT ESTIMATES. NADINE CONTINUES TO INGEST SOME DRY AIR EVEN THOUGH THE VERTICAL SHEAR APPEARS TO BE LESSENING. THE SHEAR IS FORECAST TO DECREASE FURTHER DURING THE NEXT DAY OR SO AS NADINE MOVES SOUTHWARD OVER SLIGHTLY WARMER WATERS. THESE FACTORS FAVOR SOME STRENGTHENING...HOWEVER ANOTHER SURGE OF DRIER AIR IS FORECAST TO IMPINGE ON THE CYCLONE FROM THE NORTH IN A DAY OR TWO. THIS IS LIKELY TO LIMIT ANY SIGNIFICANT STRENGTHENING AND THE NHC FORECAST ONLY CALLS FOR A VERY GRADUAL INCREASE IN WIND SPEED DURING THE NEXT 2-3 DAYS. NADINE HAS TURNED WEST-SOUTHWESTWARD WITH AN INITIAL MOTION OF 250/5. THE STORM IS FORECAST TO TURN SOUTHWARD DURING THE NEXT 24 HOURS AS NORTHERLY MID-LEVEL FLOW INCREASES BETWEEN A DEEPENING TROUGH OVER THE EASTERN ATLANTIC AND A STRONG RIDGE TO THE NORTHWEST OF THE SYSTEM. THE CYCLONE SHOULD BEGIN MOVING SLOWLY WESTWARD IN A FEW DAYS...THEN TURN NORTHWESTWARD LATER IN THE PERIOD AS THE LARGE RIDGE SHIFTS EASTWARD. THE NEW NHC TRACK HAS BEEN ADJUSTED SOUTHWARD THROUGH 72 HOURS TO BE IN BETTER AGREEMENT WITH THE LATEST GUIDANCE. THEREAFTER...THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY AND IS NEAR THE DYNAMICAL MODEL CONSENSUS. THERE CONTINUES TO BE LOWER CONFIDENCE THAN NORMAL IN THE TRACK PREDICTION AT DAYS 4 AND 5 BECAUSE OF THE UNUSUALLY LARGE SPREAD IN THE MODEL GUIDANCE. FORECAST POSITIONS AND MAX WINDS INIT 25/1500Z 31.9N 30.0W 40 KT 45 MPH 12H 26/0000Z 31.2N 30.4W 45 KT 50 MPH 24H 26/1200Z 30.4N 30.5W 45 KT 50 MPH 36H 27/0000Z 29.5N 30.6W 45 KT 50 MPH 48H 27/1200Z 28.6N 31.2W 50 KT 60 MPH 72H 28/1200Z 28.6N 32.5W 55 KT 65 MPH 96H 29/1200Z 30.0N 33.8W 55 KT 65 MPH 120H 30/1200Z 32.0N 35.0W 50 KT 60 MPH $$ FORECASTER BROWN |