000 WTNT44 KNHC 150246 TCDAT4 HURRICANE NADINE DISCUSSION NUMBER 15 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142012 1100 PM AST FRI SEP 14 2012 NADINE HAS GOTTEN BETTER ORGANIZED OVER THE PAST FEW HOURS...WITH THE CORE CONVECTION BECOMING MORE SYMMETRICAL AND MICROWAVE IMAGERY SHOWING THAT THE LOW-LEVEL CENTER IS LOCATED A LITTLE CLOSER TO THE DEEP CONVECTION. SATELLITE INTENSITY ESTIMATES RANGE FROM 65 KT FROM TAFB TO 77 KT FROM SAB AND THE UW-CIMSS ADT. GIVEN THAT SOME TILT STILL APPEARS TO EXIST IN THE CIRCULATION...THE INITIAL INTENSITY WILL BE BASED ON THE MORE CONSERVATIVE ESTIMATE FOR THIS ADVISORY. SOUTHWESTERLY VERTICAL SHEAR OF 25 TO 30 KT IS AFFECTING NADINE...AND THIS MODERATE TO STRONG SHEAR IS FORECAST TO CONTINUE FOR THE NEXT SEVERAL DAYS. GIVEN THIS MARGINAL ENVIRONMENT...ONLY MINIMAL STRENGTHENING IS FORECAST IN THE SHORT TERM. LATE IN THE PERIOD...THE CYCLONE WILL BE MOVING OVER COOLER WATERS...WHICH IN COMBINATION WITH EVEN STRONGER SHEAR SHOULD LEAD TO GRADUAL WEAKENING. THE NEW NHC INTENSITY FORECAST IS CLOSE TO THE DECAY SHIPS MODEL THROUGH 72 HOURS AND TRENDS TOWARD THE LGEM BY DAY 5. THE INITIAL MOTION ESTIMATE IS 025/12...AS NADINE IS MOVING AROUND THE NORTHWESTERN SIDE OF THE SUBTROPICAL RIDGE. THE CYCLONE WILL ENTER THE MID-LATITUDE WESTERLIES WITHIN 24 HOURS...WHICH SHOULD RESULT IN A QUICK EASTWARD MOTION UNTIL ABOUT DAY 3. A SLOWER MOTION TOWARD THE NORTHEAST IS EXPECTED AT DAYS 4 AND 5 AS AN UPPER-LEVEL TROUGH APPROACHES FROM THE WEST. THE GLOBAL MODEL GUIDANCE IS IN GENERALLY GOOD AGREEMENT ON THIS SCENARIO...WHILE THE REGIONAL HURRICANE MODELS APPEAR TO BE OUTLIERS AT THIS TIME. THE NHC FORECAST IS LARGELY AN UPDATE OF THE PREVIOUS ONE...BUT WITH A FASTER FORWARD SPEED THROUGH 72 HOURS. THE NEW NHC TRACK IS VERY CLOSE TO A BLEND OF THE GFS...ECMWF...UKMET...AND THE GEFS ENSEMBLE MEAN...AND LIES NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE. NADINE MARKS THE THIRD-EARLIEST FORMATION OF AN EIGHTH HURRICANE FOR THE SEASON IN THE ATLANTIC BASIN...BEHIND 1893 AND 2005. FORECAST POSITIONS AND MAX WINDS INIT 15/0300Z 30.0N 52.8W 65 KT 75 MPH 12H 15/1200Z 30.8N 51.4W 70 KT 80 MPH 24H 16/0000Z 31.2N 48.7W 70 KT 80 MPH 36H 16/1200Z 31.1N 45.5W 70 KT 80 MPH 48H 17/0000Z 31.2N 42.1W 70 KT 80 MPH 72H 18/0000Z 33.0N 36.0W 65 KT 75 MPH 96H 19/0000Z 35.5N 33.0W 60 KT 70 MPH 120H 20/0000Z 37.5N 31.5W 50 KT 60 MPH $$ FORECASTER BRENNAN