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| #377453 (Received by flhurricane at: 4:55 AM 20.Sep.2010) TCDAT1 HURRICANE IGOR DISCUSSION NUMBER 49 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010 500 AM AST MON SEP 20 2010 DEEP CONVECTION HAS BEEN SPUTTERING NEAR THE CENTER OF IGOR OVER THE PAST FEW HOURS...HOWEVER SATELLITE CLASSIFICATIONS AND EARLIER SURFACE OBSERVATIONS FROM BERMUDA SUPPORT KEEPING IGOR AT HURRICANE INTENSITY. LITTLE CHANGE IN STRENGTH IS EXPECTED BEFORE IGOR UNDERGOES EXTRATROPICAL TRANSITION...WHICH SHOULD BE COMPLETE BY 36 HOURS WHEN GLOBAL MODEL FIELDS SHOW THE CYCLONE BECOMING FULLY EMBEDDED WITHIN A BAROCLINIC ZONE. POST-TROPICAL IGOR IS EXPECTED TO REMAIN A STRONG EXTRATROPICAL CYCLONE FOR A DAY OR TWO BEFORE WEAKENING LATE IN THE PERIOD. THE LATEST SATELLITE FIXES SUGGEST THAT THE FORWARD MOTION OF IGOR HAS INCREASED...AND THE INITIAL MOTION ESTIMATE IS 025/17. IGOR WILL CONTINUE TO ACCELERATE TOWARD THE NORTHEAST AS IT RECURVES AHEAD OF A MID-LATITUDE TROUGH OVER THE CANADIAN MARITIMES DURING THE NEXT COUPLE OF DAYS. BY DAYS 3 AND 4 IGOR WILL TURN NORTHWARD AND THEN NORTHWESTWARD AS IT INTERACTS WITH AN UPPER-LEVEL LOW MOVING EASTWARD FROM NORTHERN QUEBEC INTO THE DAVIS STRAIT. THE GLOBAL MODEL GUIDANCE SHOWS A FASTER FORWARD SPEED IN THE FIRST COUPLE OF DAYS...AND THE OFFICIAL FORECAST HAS BEEN ADJUSTED IN THAT DIRECTION AND LIES ON THE LEFT SIDE OF THE GUIDANCE SUITE...BUT TO THE RIGHT OF THE GFS. FROM 48 HOURS ONWARD...THE NEW FORECAST IS A BLEND OF THE PREVIOUS NHC FORECAST AND THE GFS ENSEMBLE MEAN. HOWEVER...MODEL SPREAD IS QUITE LARGE AT THE END OF THE PERIOD DUE TO DIFFERENCES IN HOW IGOR INTERACTS WITH THE UPPER LOW...AND CONFIDENCE IN TRACK FORECAST NEAR THE END OF THE PERIOD IS LOW. TROPICAL STORM CONDITIONS ARE STILL BEING FELT ON BERMUDA...BUT SHOULD GRADUALLY DIMINISH TODAY. STRONG WINDS ARE POSSIBLE ALONG THE COAST OF NEWFOUNDLAND AS IGOR PASSES BY...AND THE CANADIAN HURRICANE CENTRE HAS ISSUED A TROPICAL STORM WATCH FOR A PORTION OF THAT PROVINCE. FORECAST POSITIONS AND MAX WINDS INITIAL 20/0900Z 34.2N 64.4W 65 KT 12HR VT 20/1800Z 36.7N 62.4W 65 KT 24HR VT 21/0600Z 40.6N 57.6W 65 KT 36HR VT 21/1800Z 45.6N 50.8W 70 KT...POST-TROP/EXTRATROP 48HR VT 22/0600Z 47.7N 44.5W 65 KT...POST-TROP/EXTRATROP 72HR VT 23/0600Z 55.0N 37.0W 55 KT...POST-TROP/EXTRATROP 96HR VT 24/0600Z 61.0N 41.0W 35 KT...POST-TROP/EXTRATROP 120HR VT 25/0600Z...DISSIPATED $$ FORECASTER BRENNAN |
