000 WTPZ44 KNHC 211443 TCDEP4 Hurricane Willa Discussion Number 6 NWS National Hurricane Center Miami FL EP242018 900 AM MDT Sun Oct 21 2018 First-light GOES-16 visible satellite imagery shows that Willa continues to become better organized, with a tightly coiled band of convection wrapping around the center. There has also been evidence of a small eye in recent microwave and infrared satellite pictures. Subjective and objective satellite intensity estimates range from 77 kt to 90 kt, and the initial intensity has been increased to 85 kt for this advisory. Willa is moving northwestward or 325/6 kt. The track guidance continues to indicate that Willa will move northwestward today, then turn northward on Monday, and then head north-northeastward on Tuesday between a deep-layer ridge that extends westward from the Gulf of Mexico and an approaching mid-level trough. The dynamical model guidance remains in good overall agreement on this scenario, but there are differences in how quickly Willa will accelerate north-northeastward. The UKMET and ECMWF are much slower than the remainder of the dynamical models, with the GFS and GFS ensemble mean the fastest. The NHC track forecast brings the center of the Willa onshore of the coast of southwestern Mexico within 72 h, and it lies closest to the HFIP corrected consensus, which is a little faster than the other consensus aids. The hurricane is expected to remain within low vertical wind shear and over warm waters of around 28 degrees Celsius during the next day or two. These very favorable conditions are expected to allow steady to rapid strengthening through Monday night, and the NHC forecast is near the upper end of the intensity guidance. By 48 hours, increasing southwesterly shear is forecast to initiate weakening, but Willa is likely to remain a very strong hurricane through landfall in southwestern Mexico. After landfall, rapid weakening and dissipation over the mountainous terrain of mainland Mexico should occur. Key Messages: 1. Willa is forecast to be a hurricane when it reaches the coast of southwestern mainland Mexico by late Tuesday or Wednesday bringing a life-threatening storm surge, dangerous winds, and life-threatening flash flooding, and hurricane and tropical storm watches are now in effect for a portion of the area. Residents in the watch areas should monitor the progress of this system and follow any advice given by local officials. FORECAST POSITIONS AND MAX WINDS INIT 21/1500Z 16.6N 106.7W 85 KT 100 MPH 12H 22/0000Z 17.2N 107.2W 95 KT 110 MPH 24H 22/1200Z 18.2N 107.6W 110 KT 125 MPH 36H 23/0000Z 19.3N 107.7W 120 KT 140 MPH 48H 23/1200Z 20.4N 107.5W 110 KT 125 MPH 72H 24/1200Z 23.3N 105.5W 80 KT 90 MPH...INLAND 96H 25/1200Z 26.5N 101.0W 20 KT 25 MPH...POST-TROP/INLAND 120H 26/1200Z...DISSIPATED $$ Forecaster Brown