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#875730 (Received by flhurricane at: 5:07 PM 23.Sep.2016) TCDAT2 TROPICAL STORM KARL DISCUSSION NUMBER 38 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122016 ISSUED BY THE NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 500 PM AST FRI SEP 23 2016 Satellite imagery contintues to show a well-developed outflow pattern around Karl with the center noted on the southeastern edge of the colder cloud tops. Aircraft reconnaissance data has indicated a gradual drop in pressure to 988 mb, based on a dropsonde report of 989 mb with 12 kt of wind at the surface. A peak 850-mb flight-level wind of 62 kt was measured, which equates to an surface intensity of 50 kt. Reliable SFMR data also showed maximum surface winds around 50 kt, and that will remain the initial intensity. Latest aircraft fixes had also indicated that Karl was beginning to turn more northward as it moves around the western edge of the mid-Atlantic subtropical ridge. Karl is expected to remain over sea surface temperatures of between 29-30C for the next 24 hours or so while at the same time, some brief relaxation in the vertical shear is forecast. These conditions should favor some continued slow strenghthening, which is generally supported by a majority of models. The models also suggest that Karl could reach hurricane strength by 24 hours as the system moves to the east of Bermuda. Continued strengthening of Karl is likely through 36 hours, then it is expected to gradually transition to extratropical status by 48 hours as it becomes absorbed by a rapidly approaching cold front. The latest official forecast has shifted Karl slightly west of the previous track during the next 12 hours, but otherwise, there are no significant changes from the previous advisory. Karl should make a sharp turn and acceleration to the northeast beyond 12 hours as it encounters increasing westerly flow in advance of an amplifying upper trough and associated cold front across the northwest Atlantic. Karl should then become absorbed by another extratropical low over the north Atlantic in 72 hours. FORECAST POSITIONS AND MAX WINDS INIT 23/2100Z 29.9N 65.1W 50 KT 60 MPH 12H 24/0600Z 31.3N 64.3W 55 KT 65 MPH 24H 24/1800Z 33.7N 60.8W 65 KT 75 MPH 36H 25/0600Z 37.1N 54.0W 70 KT 80 MPH 48H 25/1800Z 42.0N 44.6W 65 KT 75 MPH...POST-TROP/EXTRATROP 72H 26/1800Z...DISSIPATED $$ Forecaster Sullivan/Berg |