000 WTPZ43 KNHC 210846 TCDEP3 Hurricane Kenneth Discussion Number 12 NWS National Hurricane Center Miami FL EP132017 200 AM PDT Mon Aug 21 2017 Kenneth has continued to rapidly intensify since the previous advisory. The satellite presentation of the hurricane is quite impressive, as a 15-nmi wide eye has become better defined while the cloud tops of the surrounding ring of convection has cooled. Dvorak intensity estimates range from T5.5 (102 kt) from SAB, T6.0 (115 kt) from TAFB, to T6.3 (122 kt) from UW/CIMSS. Using a blend of these estimates, the initial wind speed has been increased to 115 kt, making Kenneth a category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale. The hurricane is expected to peak in intensity very soon as it will be moving over cooler waters and into a more stable air mass later today. After that time, cooler sea surface temperatures and less favorable thermodynamic conditions should cause steady weakening. In 3 to 4 days, increasing southwesterly shear from an upper-level trough along 140W and sub 23C SSTs should cause Kenneth's deep convection to dissipate, resulting in the system becoming a post-tropical cyclone. The NHC intensity forecast is slightly higher than the previous one at 12 and 24 h due to the higher initial intensity. After that time, the forecast is fairly similar to the previous advisory, and is a blend of the various intensity aids. The initial motion estimate is west-northwest or 300 degrees at 9 kt. The track forecast reasoning remains the same as the previous advisory, as Kenneth is expected to turn northwestward today, then north-northwestward on Tuesday between a mid-level ridge to its east and a developing cut-off low to the west. Kenneth should slow down considerably later in the period when it becomes a vertically shallow system and is steered by the weaker low-level flow. There is very little spread in the track guidance, and the updated official forecast is near the middle of the guidance envelope, and very close to the previous NHC forecast. FORECAST POSITIONS AND MAX WINDS INIT 21/0900Z 17.4N 130.0W 115 KT 130 MPH 12H 21/1800Z 18.2N 131.2W 115 KT 130 MPH 24H 22/0600Z 19.7N 132.3W 105 KT 120 MPH 36H 22/1800Z 21.3N 133.3W 85 KT 100 MPH 48H 23/0600Z 23.1N 134.1W 65 KT 75 MPH 72H 24/0600Z 26.6N 135.5W 45 KT 50 MPH 96H 25/0600Z 29.0N 136.3W 35 KT 40 MPH...POST-TROPICAL 120H 26/0600Z 30.5N 137.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Brown