000 WTNT42 KNHC 100856 TCDAT2 TROPICAL STORM KATE DISCUSSION NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122015 400 AM EST TUE NOV 10 2015 Kate's convective structure hasn't changed much from the previous advisory. The center is located beneath a small central dense overcast with broken banding over the northeastern quadrant. The initial intensity remains 50 kt based on a blend of Dvorak numbers of T3.5/55 kt from TAFB and T3.0/45 kt from SAB. A NOAA P-3 aircraft recently reached Kate, and on its first pass through the center it reported peak 700-mb flight-level winds of 45 kt and surface winds between 40-45 kt. In addition, the central pressure has fallen to 1003 mb. The plane will be making a few more passes through the center during the next couple of hours. Although vertical shear is forecast to increase during the next couple of days and Kate will be moving over water colder than 26C within the next 12-24 hours, all of the reliable intensity models indicate that the cyclone should strengthen and reach hurricane strength by 36 hours, if not sooner. After 36 hours, the shear is expected to increase to nearly 50 kt, which should cause Kate to become post-tropical. One significant change on this cycle is that the 00Z GFS, UKMET, Canadian, and to some extent the ECMWF now show Kate becoming the dominant low pressure area over the north Atlantic in a few days instead of being absorbed by a separate extratropical low. Therefore, the updated NHC is now extended beyond 48 hours, showing Kate as a growing extratropical low over the north Atlantic on days 3-5. Kate is accelerating northward with an initial motion of 010/15 kt. The cyclone is forecast to turn northeastward and east-northeastward and accelerate further through Wednesday as it becomes embedded in the mid-latitude westerlies. Kate is likely to slow down around day 3 when it becomes extratropical, but it should resume a faster northeastward motion toward the far north Atlantic on days 4 and 5. The new NHC track forecast is primarily an update of the previous forecast through 48 hours, and the extended extratropical portion beyond day 3 is generally a blend of the GFS and ECMWF models. FORECAST POSITIONS AND MAX WINDS INIT 10/0900Z 28.8N 75.8W 50 KT 60 MPH 12H 10/1800Z 31.0N 73.7W 55 KT 65 MPH 24H 11/0600Z 33.9N 68.3W 60 KT 70 MPH 36H 11/1800Z 36.6N 60.7W 65 KT 75 MPH 48H 12/0600Z 39.2N 54.0W 65 KT 75 MPH...POST-TROPICAL 72H 13/0600Z 43.0N 48.5W 55 KT 65 MPH...POST-TROP/EXTRATROP 96H 14/0600Z 46.0N 39.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 15/0600Z 53.0N 27.0W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ Forecaster Berg