000 WTNT44 KNHC 160257 TCDAT4 HURRICANE NADINE DISCUSSION NUMBER 19 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142012 1100 PM AST SAT SEP 15 2012 THE STRUCTURE OF NADINE HAS NOT CHANGED MUCH THIS EVENING. RECENT MICROWAVE IMAGERY INDICATES THAT THE LOW-LEVEL CENTER REMAINS DISPLACED TO THE SOUTHWEST OF THE MID-LEVEL CENTER BY ABOUT 30 N MI...LIKELY DUE TO THE 30 KT OF WESTERLY SHEAR AS ANALYZED BY UW-CIMSS SATELLITE ANALYSES AND THE SHIPS MODEL. THE INITIAL INTENSITY IS HELD AT 70 KT BASED ON A BLEND OF THE 00Z UW-CIMSS ADT ESTIMATE AND THE LATEST DVORAK ESTIMATES FROM TAFB AND SAB. NADINE IS EXPECTED TO REMAIN IN A MODERATE TO STRONG WESTERLY TO SOUTHWESTERLY SHEAR ENVIRONMENT THOUGH THE FORECAST PERIOD. MOST OF THE INTENSITY GUIDANCE INDICATES LITTLE CHANGE FOR THE NEXT DAY OR SO...FOLLOWED BY GRADUAL WEAKENING AS THE CYCLONE MOVES OVER PROGRESSIVELY COOLER WATERS. THE NHC FORECAST HAS BEEN ADJUSTED DOWNWARD JUST A LITTLE...BUT STILL KEEPS NADINE AS A HURRICANE FOR THE NEXT COUPLE OF DAYS. AT 36 HOURS AND BEYOND THE NHC FORECAST IS CLOSE TO THE LATEST INTENSITY CONSENSUS. THE INITIAL MOTION ESTIMATE IS 095/15...AS NADINE HAS MOVED A LITTLE SOUTH OF DUE EAST OVER THE PAST FEW HOURS. A SHORTWAVE MID-LEVEL RIDGE CENTERED ALONG 50W SHOULD CONTINUE TO PUSH NADINE SOUTH OF DUE EAST FOR THE NEXT 12 HOURS OR SO. NADINE IS FORECAST TO GRADUALLY TURN NORTHEASTWARD BY 48 HOURS AS THE CYCLONE MOVES TOWARD A DEEP-LAYER LOW NEAR THE AZORES. THIS LOW THEN MOVES EASTWARD AND WEAKENS AS A COMPLEX STEERING PATTERN EVOLVES OVER THE NORTHEASTERN ATLANTIC. NADINE SHOULD TURN SLOWLY NORTHWARD BY DAY 4 AS THE CYCLONE BECOMES SITUATED BETWEEN A RIDGE TO THE EAST...A MID/ UPPER-LEVEL LOW TO THE SOUTHWEST...AND A SECOND RIDGE BUILDING TO THE NORTHWEST. BY DAY 5 ANOTHER MID/UPPER-LEVEL LOW DIGS SOUTH TO THE NORTHEAST OF NADINE. THERE HAS BEEN LARGE RUN-TO-RUN VARIABILITY WITH THE INTERACTION OF NADINE AND THIS LOW. SOME SOLUTIONS HAVE SHOWN NADINE MERGING WITH THE LOW...WHILE THE LATEST RUNS OF THE ECMWF AND GFS KEEP THE LOW FARTHER EAST AND TURN NADINE SOUTHWARD. THE NEW NHC FORECAST IS CLOSE TO A BLEND OF THE ECMWF... GFS...GEFS ENSEMBLE MEAN AND THE FSU SUPERENSEMBLE THROUGH THE PERIOD...WHICH RESULTS IN LITTLE CHANGE FROM THE PREVIOUS FORECAST THROUGH 72 HOURS. THE NEW NHC TRACK SHOWS A SHARPER NORTHWARD TURN AT DAY 4 BUT INTRODUCES A SLOW SOUTHEASTWARD MOTION AT DAY 5. THIS MOTION IS SLOWER THAN THE GFS AND ECMWF HOWEVER...DUE TO THE LARGE UNCERTAINTY AT THESE TIME RANGES. FORECAST POSITIONS AND MAX WINDS INIT 16/0300Z 30.6N 46.6W 70 KT 80 MPH 12H 16/1200Z 30.5N 43.8W 70 KT 80 MPH 24H 17/0000Z 30.9N 40.0W 70 KT 80 MPH 36H 17/1200Z 31.8N 37.0W 65 KT 75 MPH 48H 18/0000Z 33.0N 34.8W 65 KT 75 MPH 72H 19/0000Z 35.5N 32.5W 60 KT 70 MPH 96H 20/0000Z 37.0N 32.0W 55 KT 65 MPH 120H 21/0000Z 36.5N 31.5W 50 KT 60 MPH $$ FORECASTER BRENNAN