000 WTNT44 KNHC 141440 TCDAT4 TROPICAL STORM NADINE DISCUSSION NUMBER 13 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142012 ISSUED BY THE HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD 1100 AM AST FRI SEP 14 2012 NADINE CONTINUES TO SHOW LITTLE CHANGE IN ORGANIZATION ON SATELLITE IMAGERY. THE LOW CLOUD LINES ON VISIBLE IMAGERY SUGGEST THAT THE CENTER IS DISPLACED A LITTLE TO THE SOUTHWESTERN PART OF THE CENTRAL DENSE OVERCAST. DVORAK INTENSITY ESTIMATES FROM TAFB AND SAB REMAIN AT 65 AND 55 KT...RESPECTIVELY...SO THE CURRENT INTENSITY ESTIMATE IS KEPT AT 60 KT. THE INTENSITY FORECAST FOR NADINE HAS BEEN A BIT CHALLENGING AS THE SYSTEM HAS REMAINED IN A MARGINAL ATMOSPHERIC ENVIRONMENT OVER THE PAST FEW DAYS. A LARGE UPPER-LEVEL TROUGH IN THE VICINITY OF 65-70W LONGITUDE HAS BEEN PRODUCING SOUTHWESTERLY SHEAR OVER NADINE. AS THE TROPICAL CYCLONE MOVES NORTHEASTWARD TO EASTWARD OVER THE NEXT FEW DAYS...THE INFLUENCE OF THIS TROUGH WILL DIMINISH. THE GLOBAL MODELS THEN SHOW AN UPPER-LEVEL RIDGE MOVING MORE OR LESS IN TANDEM WITH THE TROPICAL CYCLONE DURING THE FORECAST PERIOD. THESE MODELS INDICATE THAT SOME DECREASE IN SHEAR IS LIKELY IN A FEW DAYS...WHICH WOULD GIVE NADINE THE OPPORTUNITY FOR SOME STRENGTHENING. THIS IS REFLECTED IN THE OFFICIAL FORECAST...WHICH IS ALSO IN GOOD AGREEMENT A CONSENSUS THAT INCLUDES GUIDANCE FROM THE HURRICANE FORECAST IMPROVEMENT PROGRAM...HFIP...MODELS. NADINE HAS MADE ITS EXPECTED TURN TO THE NORTH AND THE INITIAL MOTION IS NOW 360/14. THE TROPICAL CYCLONE SHOULD CONTINUE TO MOVE AROUND THE PERIPHERY OF A SUBTROPICAL RIDGE AND TURN EASTWARD IN THE FLOW ON THE NORTH SIDE OF THE RIDGE. BY THE END OF THE FORECAST PERIOD...NADINE IS EXPECTED TO TURN TOWARD THE LEFT AS IT INTERACTS WITH A CYCLONIC CIRCULATION NEAR THE AZORES. THE GUIDANCE ENVELOPE IS BRACKETED BY THE ECMWF TO THE RIGHT/SOUTH AND THE GFDL TO THE LEFT/NORTH. THE OFFICIAL TRACK FORECAST IS CLOSE TO THE PREVIOUS ONE...AND LIES BETWEEN THE GFS AND THE MULTI-MODEL CONSENSUS TVCN. FORECAST POSITIONS AND MAX WINDS INIT 14/1500Z 28.0N 53.5W 60 KT 70 MPH 12H 15/0000Z 29.6N 53.1W 60 KT 70 MPH 24H 15/1200Z 31.0N 51.5W 60 KT 70 MPH 36H 16/0000Z 31.5N 49.4W 60 KT 70 MPH 48H 16/1200Z 31.8N 46.8W 65 KT 75 MPH 72H 17/1200Z 32.5N 40.5W 65 KT 75 MPH 96H 18/1200Z 34.5N 35.0W 65 KT 75 MPH 120H 19/1200Z 36.5N 30.5W 60 KT 70 MPH $$ FORECASTER PASCH/HAMRICK/FRACASSO