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| #535516 (Received by flhurricane at: 10:44 PM 19.Aug.2012) TCDAT3 HURRICANE GORDON DISCUSSION NUMBER 18 NWS NATIONAL HURRICANE CENTER MIAMI FL AL082012 1100 PM AST SUN AUG 19 2012 THE EYE DISAPPEARED ON SATELLITE IMAGERY SEVERAL HOURS AGO AND THE CLOUD PATTERN IS BECOMING INCREASINGLY RAGGED. A RECENT ASCAT PASS OVER THE HURRICANE SHOWED THAT THE CENTER IS LOCATED IN THE SOUTHWEST PART OF THE CLOUD MASS...BUT THAT THE CIRCULATION IS STILL QUITE STRONG. THE CURRENT INTENSITY ESTIMATE OF 70 KT IS BASED ON AN ASSUMED SLOW WEAKENING RATE AND IS CONSISTENT WITH A BLEND OF T- AND CI-NUMBERS FROM TAFB AND SAB. THE COMBINATION OF INCREASED SOUTHWESTERLY SHEAR AND COOLER WATERS SHOULD LEAD TO STEADY WEAKENING. GORDON IS LIKELY TO BECOME A POST-TROPICAL CYCLONE IN 24-36 HOURS AND THE CYCLONE SHOULD DISSIPATE IN 72 HOURS OR LESS. THE OFFICIAL INTENSITY FORECAST IS CLOSE TO THE LATEST SHIPS OUTPUT...BUT IS IS WORTH NOTING THAT THE DIAGNOSTICS FROM THAT MODEL SHOW GORDON LOSING TROPICAL CHARACTERISTICS ON MONDAY. NOW THAT THE CENTER HAS MORE BECOME DIFFICULT TO FIND...THE INITIAL MOTION IS A RATHER UNCERTAIN 070/17...OR PERHAPS A LITTLE SLOWER. THE HURRICANE CONTINUES TO BE EMBEDDED IN A WESTERLY CURRENT TO THE SOUTH OF A LARGE LOW OVER THE NORTHEASTERN ATLANTIC. AS THE UPPER-LEVEL CIRCULATION OF GORDON IS LIKELY TO BE SHEARED AWAY BY STRONG UPPER-LEVEL WINDS IN ABOUT 36 HOURS...GORDON OR ITS POST-TROPICAL COUNTERPART SHOULD BECOME A SHALLOW CYCLONE STEERED MAINLY BY THE WEAKER LOW-LEVEL FLOW. THEREFORE A CONSIDERABLE SLOWING OF THE FORWARD SPEED IS ANTICIPATED. THE OFFICIAL TRACK FORECAST IS CLOSE TO THE DYNAMICAL MODEL CONSENSUS BUT A BIT FASTER THAN THE LATEST GFS TRACK. THE INITIAL AND FORECAST WIND RADII HAVE BEEN ADJUSTED BASED ON THE TIMELY ASCAT PASS. FORECAST POSITIONS AND MAX WINDS INIT 20/0300Z 36.7N 25.8W 70 KT 80 MPH 12H 20/1200Z 37.8N 23.3W 55 KT 65 MPH 24H 21/0000Z 38.8N 20.8W 45 KT 50 MPH 36H 21/1200Z 39.2N 19.3W 35 KT 40 MPH...POST-TROPICAL 48H 22/0000Z 39.3N 18.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 23/0000Z...DISSIPATED $$ FORECASTER PASCH |
