000 WTPZ43 KNHC 070844 TCDEP3 HURRICANE BLAS DISCUSSION NUMBER 18 NWS NATIONAL HURRICANE CENTER MIAMI FL EP032016 200 AM PDT THU JUL 07 2016 Blas continues to maintain an impressive satellite presentation, with a distinct 20 n mi wide eye surrounded by a ring of cold convective tops. Overall, the cyclone has been steady-state for the last 24 hours or so, consistent with some annular hurricane characteristics such as minimal convective banding and a large eye. The initial intensity remains 110 kt based on the latest Dvorak classifications of T5.5/6.0 from TAFB and SAB. The hurricane will be moving over cooler waters and into a more stable atmospheric environment during the next 12 to 24 hours, which should result in the onset of weakening. Weakening should continue after that time, with Blas expected to move over SSTs of about 24C in 48 hours. Deep convection is expected to dissipate late in the period, and Blas should become post-tropical in 4 days, or perhaps a bit sooner. The official forecast is close to the latest IVCN intensity consensus aid. The initial motion estimate is 290/09, as Blas continues to be steered around the southwestern periphery of a distant mid-level ridge centered over northern Mexico. The hurricane is forecast to turn northwestward in 24-36 hours as it reaches the western edge of the ridge, and the track model guidance is in good agreement on this scenario. Through 48 hours the NHC track has been shifted a bit north of the previous one following the latest trend in the guidance. Afterward, most of the guidance shows a continued west-northwestward or northwestward motion through 72 hours as Blas interacts with an upper-level closed low northeast of the Hawaiian Islands, followed by the shallow post-tropical Blas turning westward. The ECMWF continues to show less interaction with the upper-level low, and turns Blas westward and west-southwestward at days 4 and 5. Compared to 24 hours ago, the GFS-based guidance has shifted southward and the ECMWF has trended a bit northward, suggesting that a consensus approach is still the best solution. The new NHC track at days 3 through 5 is close to the previous one and near the middle of the guidance envelope. This track is a little south of the latest multi-model consensus but well north of the ECMWF. FORECAST POSITIONS AND MAX WINDS INIT 07/0900Z 15.9N 126.4W 110 KT 125 MPH 12H 07/1800Z 16.4N 127.6W 100 KT 115 MPH 24H 08/0600Z 17.2N 129.1W 85 KT 100 MPH 36H 08/1800Z 18.3N 130.4W 70 KT 80 MPH 48H 09/0600Z 19.5N 131.8W 60 KT 70 MPH 72H 10/0600Z 21.5N 135.0W 40 KT 45 MPH 96H 11/0600Z 22.0N 139.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 12/0600Z 22.0N 143.5W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Brennan