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| #377332 (Received by flhurricane at: 4:49 PM 19.Sep.2010) TCDAT1 HURRICANE IGOR DISCUSSION NUMBER 47 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010 500 PM AST SUN SEP 19 2010 THE AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT HAS MEASURED PEAK FLIGHT-LEVEL AND SFMR WINDS OF 82 KT AND 68 KT...RESPECTIVELY. BASED ON THESE DATA...THE INITIAL INTENSITY IS LOWERED SLIGHTLY TO 70 KT. THE WIND FIELD REMAINS QUITE LARGE AND SOME OF THE WIND RADII HAVE BEEN EXPENDED OUTWARD BASED ON THE AIRCRAFT AND EARLIER ASCAT DATA. LITTLE CHANGE IN INTENSITY IS EXPECTED WHILE IGOR REMAINS A TROPICAL CYCLONE. THE GLOBAL MODELS INDICATE THAT EXTRATROPICAL TRANSITION SHOULD BEGIN ON MONDAY...AND BE COMPLETED IN ABOUT 48 HOURS. GRADUAL WEAKENING IS SHOWN BY THE DYNAMICAL MODELS AFTER IGOR BECOMES EXTRATROPICAL...AND THIS IS REFLECTED IN THE OFFICIAL FORECAST. THE AIRCRAFT FIXES WERE A FEW TENTHS OF A DEGREE WEST OF THE EARLIER SATELLITE ESTIMATES. THIS HAS REQUIRED A LITTLE ADJUSTMENT TO THE INITIAL POSITION AND MOTION. THE UPDATED POSITION HAS ALSO REQUIRED A SMALL WESTWARD SHIFT IN THE EARLY PORTION OF THE FORECAST TRACK. THERE HAVE BEEN NO CHANGES TO THE TRACK FORECAST PHILOSOPHY... HOWEVER...AND IGOR IS EXPECTED TO TURN NORTHEAST TONIGHT AHEAD OF A MID-LATITUDE TROUGH MOVING OFF THE COAST OF NORTH AMERICA. THE GLOBAL MODELS HAVE BEEN VERY INCONSISTENT IN THE EXTRATROPICAL PORTION OF THE TRACK AND THERE REMAINS A VERY LARGE SPREAD IN THE GUIDANCE AT 3 TO 5 DAYS. THE OFFICIAL FORECAST HAS BEEN ADJUSTED A LITTLE EASTWARD AT 72 HOURS AND BEYOND...TO BE IN BETTER AGREEMENT WITH THE MULTI-MODEL CONSENSUS. ALTHOUGH THE CENTER OF IGOR IS LIKELY TO PASS WEST OF BERMUDA...HURRICANE FORCE WINDS EXTEND A LARGE DISTANCE FROM THE CENTER AND SIGNIFICANT IMPACTS ARE BEING FELT ON THE ISLAND. FORECAST POSITIONS AND MAX WINDS INITIAL 19/2100Z 31.5N 65.9W 70 KT 12HR VT 20/0600Z 33.6N 65.3W 70 KT 24HR VT 20/1800Z 36.9N 62.8W 70 KT 36HR VT 21/0600Z 40.6N 58.1W 70 KT 48HR VT 21/1800Z 45.0N 52.0W 65 KT...POST-TROP/EXTRATROP 72HR VT 22/1800Z 51.0N 41.0W 55 KT...POST-TROP/EXTRATROP 96HR VT 23/1800Z 55.0N 37.5W 50 KT...POST-TROP/EXTRATROP 120HR VT 24/1800Z 60.0N 37.5W 45 KT...POST-TROP/EXTRATROP $$ FORECASTER BROWN |
