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| #376736 (Received by flhurricane at: 10:43 AM 17.Sep.2010) TCDAT1 HURRICANE IGOR DISCUSSION NUMBER 38 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010 1100 AM AST FRI SEP 17 2010 THE OVERALL CLOUD PATTERN OF IGOR HAS CHANGED LITTLE IN ORGANIZATION OVER THE PAST SEVERAL HOURS...ALTHOUGH DVORAK CI NUMBERS HAVE DECREASED TO 5.0 AND 5.5 FROM SAB AND TAFB...RESPECTIVELY. BASED UPON THESE DATA...THE INITIAL WIND SPEED IS LOWERED TO 105 KT. AN 0915 UTC SSMIS OVERPASS SHOWED THE EXISTENCE OF A NEW OUTER WIND MAXIMUM AT ABOUT 90 NMI RADIUS...WITH AN INNER EYEWALL PARTIALLY BROKEN TO THE WEST. INNER CORE DYNAMICS ASIDE...THERE IS STILL AN OPPORTUNITY FOR RE-INTENSIFICATION DURING THE NEXT DAY OR TWO WHILE IGOR IS LOCATED IN A LIGHT SHEAR ENVIRONMENT AND MOVING OVER WARM WATERS. GLOBAL MODELS FORECAST A GRADUAL INCREASE IN SOUTHERLY TO SOUTHWESTERLY SHEAR OVER THE CYCLONE AFTER ABOUT 48 HOURS AND WATERS GRADUALLY BECOME COOLER AFTER THAT. BOTH OF THESE FACTORS SUGGEST A SLOW WEAKENING OF IGOR BEGINNING AFTER ABOUT TWO DAYS...AND THE OFFICIAL NHC FORECAST IS ABOUT THE SAME AS BEFORE. THE GUIDANCE SUGGESTS THAT EXTRATROPICAL TRANSITION SHOULD BE COMPLETED BETWEEN 96 AND 120 HOURS. IGOR IS MAINTAINING A FAIRLY STEADY MOTION OF 305/08. THE STEERING FLOW AROUND THE SOUTHWEST SIDE OF A SUBTROPICAL RIDGE SHOULD GUIDE IGOR ON A NORTHWESTWARD AND THEN NORTH-NORTHWESTWARD COURSE DURING THE NEXT COUPLE OF DAYS. AFTER THAT...THE APPROACH OF A VIGOROUS SHORTWAVE TROUGH OVER THE NORTHEASTERN U.S. SHOULD GRADUALLY TURN THE HURRICANE NORTHWARD AND THEN NORTHEASTWARD WITH A SUBSTANTIAL INCREASE IN FORWARD SPEED. THE OFFICIAL NHC TRACK FORECAST IS CLOSE TO THE PREVIOUS ONE...EXCEPT FOR BEING SOMEWHAT SLOWER AT 96 AND 120 HOURS IN LINE WITH THE LATEST GUIDANCE. FORECAST POSITIONS AND MAX WINDS INITIAL 17/1500Z 23.1N 60.1W 105 KT 12HR VT 18/0000Z 24.0N 61.5W 105 KT 24HR VT 18/1200Z 25.4N 63.2W 105 KT 36HR VT 19/0000Z 27.0N 64.5W 100 KT 48HR VT 19/1200Z 28.8N 65.1W 100 KT 72HR VT 20/1200Z 34.0N 63.5W 90 KT 96HR VT 21/1200Z 41.0N 55.0W 75 KT...POST-TROP/EXTRATROP 120HR VT 22/1200Z 51.0N 44.5W 60 KT...POST-TROP/EXTRATROP $$ FORECASTER KIMBERLAIN |
