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#723794 (Received by flhurricane at: 10:38 PM 12.Oct.2014) TCDAT2 TROPICAL STORM FAY DISCUSSION NUMBER 12 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072014 1100 PM AST SUN OCT 12 2014 Fay's cloud pattern has rapidly deteriorated in organization since this afternoon due to strong southwesterly vertical wind shear. Microwave and last-light visible satellite imagery indicate that the low-level center has become exposed to the southwest of a large mass of very cold-topped convection. The same satellite data also indicate that the center has become increasingly deformed, making the initial position more uncertain than normal. This uncertainty has resulted in a large scatter in Dvorak intensity estimates. The initial intensity is lowered to 55 kt, in agreement with the latest Dvorak estimate from SAB, which was closest to the estimated center position. Even stronger west-southwesterly shear should affect Fay during the next couple of days. Meanwhile, much drier and more stable air behind a cold front impinging on the storm from the northwest should become entrained within Fay's circulation. The combination of these factors should lead to additional steady weakening, with global models showing extratropical transition occurring in about 24 hours (or perhaps sooner). The NHC intensity forecast is similar to the previous one and in excellent agreement with the latest statistical- dynamical model consensus. The exposed center in the last few visible images was south of previous estimates, and as a result the initial motion estimate is now more sharply toward the east, or 080/21. Fay is expected to continue racing eastward or east-southeastward at the base of a potent shortwave trough moving through eastern Atlantic Canada and the north Atlantic. The NHC track forecast has been adjusted toward the right of the previous one, based primarily on the new center position and motion. FORECAST POSITIONS AND MAX WINDS INIT 13/0300Z 34.1N 58.2W 55 KT 65 MPH 12H 13/1200Z 34.4N 53.6W 50 KT 60 MPH 24H 14/0000Z 33.9N 48.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 36H 14/1200Z 33.4N 42.6W 35 KT 40 MPH...POST-TROP/EXTRATROP 48H 15/0000Z 33.0N 37.0W 30 KT 35 MPH...POST-TROP/EXTRATROP 72H 16/0000Z...DISSIPATED $$ Forecaster Kimberlain |