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| #375728 (Received by flhurricane at: 4:38 AM 13.Sep.2010) TCDAT1 HURRICANE IGOR DISCUSSION NUMBER 21 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010 500 AM AST MON SEP 13 2010 IGOR REMAINS A POWERFUL AND WELL ORGANIZED HURRICANE WITH A SYMMETRIC EYEWALL...CLOUD TOPS COLDER THAN -70 C...A 15 N MI CIRCULAR EYE...AND SPIRAL RAINBANDS. SATELLITE CLASSIFICATIONS FROM ALL AGENCIES HAVE NOT CHANGED MUCH FROM 0000 UTC...AND THEREFORE THE INITIAL INTENSITY IS HELD AT 130 KT FOR THIS ADVISORY. AS IS COMMON FOR MAJOR HURRICANES IN FAVORABLE OCEANIC AND ATMOSPHERIC ENVIRONMENTS...INTERNAL DYNAMICS WILL LIKELY GOVERN THE INTENSITY CHANGE OF IGOR DURING THE NEXT DAY OR TWO. SINCE IT APPEARS THAT AN EYEWALL REPLACEMENT CYCLE HAS NOT YET BEGUN...THE OFFICIAL FORECAST WILL ALLOW FOR A LITTLE MORE STRENGTHENING TODAY. THEREAFTER...A GRADUAL WEAKENING IS SHOWN FOLLOWING THE TREND IN THE INTENSITY GUIDANCE. IGOR IS FORECAST TO MOVE INTO AN AREA OF STRONGER SHEAR BY THE END OF THE PERIOD...WHICH SHOULD CAUSE A LITTLE MORE WEAKENING. THE HURRICANE CONTINUES TO MOVE WESTWARD AT 11 KT...AND IS ON THE PREVIOUS FORECAST TRACK. IGOR IS EXPECTED TO TURN WEST- NORTHWESTWARD IN ABOUT 24 HOURS AND THEN NORTHWESTWARD IN A COUPLE OF DAYS AS IT APPROACHES A BROAD TROUGH OVER THE CENTRAL AND WESTERN ATLANTIC. ALTHOUGH MOST OF THE GLOBAL MODELS SHOW THE TROUGH FLATTENING IN 3 TO 4 DAYS...THERE ARE DISAGREEMENTS IN HOW MUCH...IF ANY...SUBTROPICAL RIDGING BUILDS IN THE WAKE OF THE TROUGH. THE ECMWF AND UKMET MODELS CONTINUE TO BUILD MORE RIDGING NORTH OF IGOR...RESULTING IN A TRACK FARTHER WEST THAN THE OTHER MODELS. OVERALL...THE MODEL GUIDANCE HAS SHIFTED SLIGHTLY TO THE RIGHT FROM THE LAST CYCLE AND THE OFFICIAL FORECAST IS NUDGED IN THAT DIRECTION...BUT REMAINS ON THE SOUTH SIDE OF THE GUIDANCE ENVELOPE. FORECAST POSITIONS AND MAX WINDS INITIAL 13/0900Z 17.7N 48.8W 130 KT 12HR VT 13/1800Z 17.9N 50.2W 140 KT 24HR VT 14/0600Z 18.5N 51.8W 135 KT 36HR VT 14/1800Z 19.3N 53.4W 130 KT 48HR VT 15/0600Z 20.4N 54.9W 125 KT 72HR VT 16/0600Z 22.5N 57.7W 120 KT 96HR VT 17/0600Z 25.0N 60.0W 115 KT 120HR VT 18/0600Z 28.0N 63.0W 105 KT $$ FORECASTER CANGIALOSI |
