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#875831 (Received by flhurricane at: 4:55 PM 24.Sep.2016) TCDAT2 TROPICAL STORM KARL DISCUSSION NUMBER 42 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122016 500 PM AST SAT SEP 24 2016 The convective pattern of Karl has become less organized today and currently resembles a shear pattern, which isn`t surprising given the 35 kt of southwesterly shear analyzed over Karl by UW-CIMSS. A GPM overpass from earlier today showed that the inner-core structure of the cyclone had degraded, and this was also noted by the last aircraft flight this morning. The initial intensity remains 55 kt based on the latest Dvorak Data-T numbers of T3.5/55 kt from TAFB and SAB. A NOAA Hurricane Hunter aircraft is en route to sample Karl and provide more data on its current intensity and structure. Karl is expected to strengthen during the next 12 to 24 hours, but much of this will be due to baroclinic effects as the cyclone will be under very high shear and moving over cooler SSTs. The NHC forecast shows Karl reaching 70 kt at 24 h as a post-tropical cyclone based on the GFS and ECMWF guidance. Karl should be absorbed by a larger extratropical low over the north Atlantic by 36 h, as indicated by global model fields. The initial motion estimate is 055/20. Karl should continue to accelerate on an east-northeastward to northeastward heading ahead of a broad deep-layer trough until the cyclone is absorbed, and the forward speed is expected to be near 50 kt by 24 hours. The new NHC track forecast is an update of the previous one and remains near the middle of the tightly packed guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 24/2100Z 33.6N 61.1W 55 KT 65 MPH 12H 25/0600Z 36.4N 55.3W 60 KT 70 MPH 24H 25/1800Z 41.9N 45.1W 70 KT 80 MPH...POST-TROPICAL 36H 26/0600Z...DISSIPATED $$ Forecaster Brennan |