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| #222532 (Received by flhurricane at: 5:00 PM 16.Oct.2008) TCDAT5 HURRICANE OMAR DISCUSSION NUMBER 14 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL152008 500 PM EDT THU OCT 16 2008 OMAR'S CENTRAL CONVECTION HAS DIMINISHED CONSIDERABLY...WHILE THE PRINCIPAL BAND TO ITS SOUTHEAST AND SOUTH STILL CONTAINS VIGOROUS DEEP CONVECTION. CONSTRAINTS ON THE DVORAK TECHNIQUE ARE STILL FORCING TAFB AND SAB TO INDICATE ABOUT A 90 KT HURRICANE. HOWEVER...BASED ON THE CONTINUING DETERIORATION OF THE CENTRAL FEATURES...THE INTENSITY IS REDUCED TO 65 KT. THE TROPICAL CYCLONE IS MOVING QUICKLY TOWARD THE NORTH-NORTHEAST... 30 DEGREES AT 23 KT...UNDER THE INFLUENCE OF A DEEP-LAYER LOW TO ITS NORTH AND MID TO LOW LEVEL RIDGE TO ITS NORTHEAST. THE TRACK GUIDANCE IS TIGHTLY CLUSTERED THROUGH 72 HR ALONG A TRACK TOWARD THE NORTHEAST. BUT AS EXTRATROPICAL TRANSITION BEGINS...THE VARIOUS MODELS SPLIT INTO TWO DIFFERENT SOLUTIONS. THE NOGAPS...UKMET...AND GFDL MODELS SUGGEST THAT THE CYCLONE WILL UNDERGO SIGNIFICANT RE-INTENSIFICATION AND EXPANSION IN SIZE NEAR THE AZORES. IN CONTRAST...THE ECMWF...GFS...AND HWRF MODELS INDICATE THAT THE CYCLONE WILL CONTINUE TO WEAKEN...BE MUCH FARTHER TO THE WEST...AND EVENTUALLY BE ABSORBED BY A LARGE EXTRATROPICAL CYCLONE OFF OF SOUTHEASTERN CANADA. THE SOLUTION FAVORED BY THIS ADVISORY IS THE LATTER SCENARIO...THOUGH IT IS DIFFICULT THIS FAR IN ADVANCE EXACTLY WHEN AND HOW EXTRATROPICAL TRANSITION WILL OCCUR. THE FORECAST TRACK IS SLOWER THAN THE PREVIOUS ADVISORY AND WEST OF THE CORRECTED MODEL CONSENSUS. DESPITE BEING OVER VERY WARM WATER...THE STRONG SOUTHWESTERLY VERTICAL SHEAR AND DRY AIR BEING WRAPPED INTO THE INNER CORE SHOULD CONTINUE TO WEAKEN OMAR. HOWEVER...THE RAPID MOTION OF THE CYCLONE TO THE NORTHEAST MAY SOMEWHAT OFFSET THE NEGATIVE IMPACT OF THE SHEAR. THE FAST FORWARD MOTION MAY ALSO CONTRIBUTE TOWARD THE WINDS ON THE RIGHT SIDE OF THE VORTEX. THUS ONLY GRADUAL WEAKENING IS INDICATED IN THE NEXT COUPLE OF DAYS. THE SHIPS AND LGEM STATISTICAL MODELS SUGGEST MORE RAPID WEAKENING TO A TROPICAL DEPRESSION...THOUGH THESE TECHNIQUES ARE HEAVILY WEIGHTING THE LARGE NEGATIVE PERSISTENCE FACTOR. THE INTENSITY FORECAST IS CLOSE TO THE GFDL AND HWRF SOLUTIONS AND IS SLIGHTLY LESS THAN INDICATED IN THE PREVIOUS ADVISORY. FORECAST POSITIONS AND MAX WINDS INITIAL 16/2100Z 22.1N 59.7W 65 KT 12HR VT 17/0600Z 25.0N 57.6W 65 KT 24HR VT 17/1800Z 28.2N 55.1W 60 KT 36HR VT 18/0600Z 30.1N 53.2W 55 KT 48HR VT 18/1800Z 32.2N 50.9W 50 KT 72HR VT 19/1800Z 36.0N 46.0W 45 KT...BECOMING EXTRATROPICAL 96HR VT 20/1800Z 38.0N 39.0W 40 KT...EXTRATROPICAL 120HR VT 21/1800Z 38.0N 31.0W 35 KT...EXTRATROPICAL $$ FORECASTER LANDSEA/STEWART |
