000 WTNT44 KNHC 232039 TCDAT4 TROPICAL STORM NADINE DISCUSSION NUMBER 45 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142012 500 PM AST SUN SEP 23 2012 THUNDERSTORM ACTIVITY ASSOCIATED WITH NADINE HAS GRADUALLY WANED SINCE THE PREVIOUS ADVISORY. THIS IS LIKELY DUE TO THE INGESTION OF SOME DRY AIR INTO THE CIRCULATION AND THE LATE AFTERNOON AND EVENING DIURNAL CONVECTIVE MINIMUM PERIOD. DVORAK CURRENT INTENSITY NUMBERS ARE UNCHANGED FROM THIS MORNING...SO THE INITIAL INTENSITY IS KEPT AT 50 KT. NADINE HAD BEEN DRIFTING NORTHWESTWARD...BUT IS NOW MOVING WEST-NORTHWESTWARD. THE CYCLONE IS EXPECTED TO CONTINUE MOVING WEST-NORTHWEST UNDER THE INFLUENCE OF A LARGE DEEP-LAYER RIDGE OVER THE CENTRAL ATLANTIC. THE TRACK GUIDANCE TURNS NADINE WEST-SOUTHWESTWARD IN 36 TO 48 HOURS AS THE RIDGE BUILDS NORTHEASTWARD AND BECOMES ORIENTED NORTHEAST TO SOUTHWEST ACROSS THE CENTRAL ATLANTIC. AFTER 72 HOURS...THE RIDGE IS EXPECTED TO WEAKEN AND SLIDE EASTWARD WHILE A BROAD MID-LEVEL TROUGH BECOMES ESTABLISHED OVER THE EAST COAST OF NORTH AMERICA AND THE WESTERN ATLANTIC. THIS SHOULD RESULT IN A TURN TOWARD THE NORTHWEST IN 4 TO 5 DAYS. THE NHC TRACK IS SIMILAR TO THE PREVIOUS OFFICIAL FORECAST AND REMAINS NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE. ENVIRONMENTAL CONDITIONS DO NOT FAVOR STRENGTHENING DURING THE NEXT DAY OR SO...AS NADINE REMAINS IN MODERATE SHEAR AND OVER MARGINAL SSTS. IN ADDITION....DRY AIR APPEARS TO HAVE WRAPPED AROUND MUCH OF THE CIRCULATION AND IT MAY TAKE SOME TIME FOR THUNDERSTORM ACTIVITY TO REDEVELOP. ONE POSSIBLE SCENARIO IS FOR NADINE TO NOT REGAIN ORGANIZED CONVECTION...AND BECOME POST-TROPICAL ONCE AGAIN. THE NHC FORECAST ASSUMES NADINE WILL REMAIN A TROPICAL CYCLONE AND IN A COUPLE OF DAYS THE CYCLONE IS FORECAST TO MOVE INTO A MORE CONDUCIVE ENVIRONMENT OF WARMER SSTS...LESS SHEAR...AND SLIGHTLY MORE LOW- TO MID-LEVEL MOISTURE. THESE CONDITIONS SHOULD ALLOW FOR GRADUAL STRENGTHENING LATER IN THE PERIOD. THE NHC INTENSITY FORECAST IS A LITTLE BELOW THE PREVIOUS ADVISORY DURING THE FIRST SEVERAL DAYS...BUT IS THE SAME AS THE EARLIER FORECAST BY DAY 5. THIS IS A LITTLE BELOW THE SHIPS/LGEM GUIDANCE...BUT IS CLOSE TO THE INTENSITY CONSENSUS. FORECAST POSITIONS AND MAX WINDS INIT 23/2100Z 31.0N 26.1W 50 KT 60 MPH 12H 24/0600Z 31.2N 26.9W 50 KT 60 MPH 24H 24/1800Z 31.5N 28.3W 50 KT 60 MPH 36H 25/0600Z 31.7N 29.7W 50 KT 60 MPH 48H 25/1800Z 31.6N 31.0W 55 KT 65 MPH 72H 26/1800Z 30.9N 32.8W 60 KT 70 MPH 96H 27/1800Z 31.0N 34.5W 65 KT 75 MPH 120H 28/1800Z 33.5N 37.0W 70 KT 80 MPH $$ FORECASTER BROWN