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| #149993 (Received by flhurricane at: 10:49 PM 08.Sep.2007) TCDAT2 TROPICAL STORM GABRIELLE DISCUSSION NUMBER 5 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072007 1100 PM EDT SAT SEP 08 2007 THE LOW-LEVEL CENTER OF GABRIELLE HAS DISAPPEARED UNDER A CIRRUS OVERCAST CAUSED BY A STRONG CONVECTIVE BURST...WHICH INCLUDED A SUPERCELL THUNDERSTORM WITH A WELL-DEFINED MESOCYCLONE ON THE MOREHEAD CITY WSR-88D. THE BURST HAS ENDED FOR NOW...BUT HAS LEFT A MID-LEVEL CIRCULATION EVIDENT IN THE DOPPLER RADAR DATA. WHILE THE RADAR WINDS DO NOT YET SHOW AN OBVIOUS INCREASE IN INTENSITY... A RECENT QUIKSCAT OVERPASS SHOWED A FEW 40-45 KT WIND VECTORS THAT WERE POSSIBLY RAIN CONTAMINATED. THE INITIAL INTENSITY REMAINS 35 KT...AND IT IS POSSIBLE THIS IS A LITTLE CONSERVATIVE. THE SURFACE CENTER IS DIFFICULT TO LOCATE IN BOTH SATELLITE AND RADAR IMAGERY...BUT IS ESTIMATED TO BE A LITTLE TO THE EAST OR SOUTHEAST OF THE MID-LEVEL CENTER. THIS MAKES THE INITIAL MOTION A SOMEWHAT UNCERTAIN 325/10. THERE IS LITTLE CHANGE TO THE TRACK FORECAST PHILOSOPHY OTHER THAN THE SLIGHTLY MORE WESTERLY POSITION. GABRIELLE SHOULD TURN NORTHWARD AROUND THE WESTERN SIDE OF A DEEP-LAYER RIDGE OVER THE WESTERN ATLANTIC DURING THE NEXT 12-24 HR. BEYOND THAT TIME...IT SHOULD ACCELERATE NORTHEASTWARD INTO THE WESTERLIES. THE CENTER OF GABRIELLE IS PASSING OVER THE GULF STREAM...AND THE VERTICAL WIND SHEAR THAT WAS AFFECTING THE SYSTEM EARLIER IS DIMINISHING. BASED ON THIS...THE INTENSITY FORECAST CALLS FOR SOME STRENGTHENING BEFORE THE CENTER REACHES THE NORTH CAROLINA COAST. GABRIELLE IS FORECAST TO MAINTAIN INTENSITY DURING EXTRATROPICAL TRANSITION...AND IT SHOULD BE ABSORBED BY A LARGER EXTRATROPICAL LOW BETWEEN 72-96 HR. FORECAST POSITIONS AND MAX WINDS INITIAL 09/0300Z 33.1N 75.7W 35 KT 12HR VT 09/1200Z 34.3N 75.9W 40 KT 24HR VT 10/0000Z 35.8N 75.6W 45 KT...INLAND 36HR VT 10/1200Z 37.1N 74.0W 45 KT...OVER WATER 48HR VT 11/0000Z 39.0N 71.0W 45 KT 72HR VT 12/0000Z 43.0N 62.5W 45 KT...EXTRATROPICAL 96HR VT 13/0000Z...DISSIPATED $$ FORECASTER BEVEN |
