000 WTNT42 KNHC 230251 TCDAT2 TROPICAL STORM KARL DISCUSSION NUMBER 35 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122016 1100 PM AST THU SEP 22 2016 Reports from Air Force Reserve and NOAA Hurricane Hunter aircraft indicate that Karl has become significantly better organized during the past 24 hours, with dropsonde data showing that a well-defined circulation now exists from the surface to 400 mb. The maximum flight-level winds were 56 kt at 8000 ft, and there were numerous SFMR surface wind estimates of 35-40 kt. The minimum central pressure estimated from the aircraft data is 1001 mb based on a 1003 mb dropsonde with surface winds of 24 kt. Based on these data and observations from NOAA buoy 41049, the initial intensity is now 40 kt. Additional aircraft data should be available starting at about 0600 UTC. The initial motion is now 315/14 as Karl continues moving northwestward between the subtropical ridge and a mid- to upper-level trough north of Hispaniola and east of the Bahamas. During the next 24-36 hours, Karl should turn northward and then northeastward as it moves through a break in the ridge into the westerlies. Subsequently, the cyclone should accelerate northeastward. The model guidance is in excellent agreement with this scenario, although there remains some spread in the forecast forward speed late in the forecast period between the slower ECMWF and the other faster models. The new forecast track remains down the center of the guidance and overall is similar to the previous track. The new forecast track is shifted a little closer to Bermuda, with the closest approach now forecast between 24 and 36 hours. While there remain some differences in the model details, Karl is expected to move into an area of decreasing vertical shear during the next 48 hours, which should allow continued development. After that, the cyclone should begin extratropical transition, which is likely to be complete by 72 hours according the the latest dynamical model guidance. The new intensity forecast is similar to the previous forecast and calls for Karl to steadily intensify to hurricane strength in about 48 hours, followed by rapid weakening after extratropical transition. The forecast also follows the dynamical models in calling for Karl to be absorbed by another extratropical low by 120 hours. FORECAST POSITIONS AND MAX WINDS INIT 23/0300Z 27.0N 64.0W 40 KT 45 MPH 12H 23/1200Z 28.4N 65.0W 45 KT 50 MPH 24H 24/0000Z 30.5N 64.8W 50 KT 60 MPH 36H 24/1200Z 32.4N 62.6W 60 KT 70 MPH 48H 25/0000Z 35.2N 57.4W 70 KT 80 MPH 72H 26/0000Z 43.5N 41.0W 70 KT 80 MPH...POST-TROP/EXTRATROP 96H 27/0000Z 53.0N 26.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 28/0000Z...ABSORBED BY EXTRATROPICAL LOW $$ Forecaster Beven