000 WTPZ44 KNHC 212034 TCDEP4 Hurricane Willa Discussion Number 7 NWS National Hurricane Center Miami FL EP242018 300 PM MDT Sun Oct 21 2018 Willa has continued to rapidly strengthen with the eye becoming very distinct in both visible and infrared satellite imagery. The surrounding convective tops warmed around mid-day but have cooled since that time and subjective Dvorak intensity estimates were 102 and 90 kt, from SAB and TAFB respectively at 18Z. With the continued increase in organization since that time, the initial intensity is set near the upper end of the estimates or 100 kt. Willa continues moving slowly north-northwestward or 330/5 kt. There has been no change to the track forecast philosophy over the past few advisories. The hurricane is expected to turn northward tonight or Monday around the western portion of a deep-layer ridge that extends westward from the Gulf of Mexico over mainland Mexico. A mid-level trough that is forecast to approach the Baja California peninsula Monday night and Tuesday should cause Willa to turn north- northeastward and recurve around the northwestern portion of the aforementioned ridge. There are still some differences in how quickly Willa will recurve, but there is little cross-track spread in the guidance. This increases the overall confidence in the NHC track forecast, which calls for the hurricane to make landfall along the southwestern coast of Mexico late Tuesday or early Wednesday. The low shear and warm ocean environment ahead of Willa is expected to remain quite favorable for strengthening for at least another 12 to 24 hours, and additional intensification is likely tonight and early Monday. The new NHC track intensity forecast is above all the intensity guidance through 36 hours, and now calls for a peak intensity of 130 kt within that time period. After that time, eyewall replacement cycles could result in some fluctuations in intensity. Increasing southwesterly shear on Tuesday could result in some weakening, but Willa is expected to approach the coast of Mexico as a very dangerous hurricane. After landfall, rapid weakening and dissipation over the mountainous terrain of mainland Mexico should occur. A 96-hour forecast point is shown for continuity but the system is likely to dissipate before that time. Key Messages: 1. Willa is forecast to be a dangerous hurricane when it reaches the coast of southwestern mainland Mexico by late Tuesday or Wednesday bringing a life-threatening storm surge, damaging hurricane-force winds, and life-threatening flash flooding. A Hurricane Watch and tropical storm warnings and watches are in effect for a portion of the area. Residents in these areas should monitor the progress of this system and follow any advice given by local officials. FORECAST POSITIONS AND MAX WINDS INIT 21/2100Z 17.0N 107.0W 100 KT 115 MPH 12H 22/0600Z 17.8N 107.4W 120 KT 140 MPH 24H 22/1800Z 18.8N 107.6W 130 KT 150 MPH 36H 23/0600Z 19.8N 107.6W 125 KT 145 MPH 48H 23/1800Z 21.0N 107.1W 110 KT 125 MPH 72H 24/1800Z 24.8N 103.3W 45 KT 50 MPH...INLAND 96H 25/1800Z 26.8N 100.0W 20 KT 25 MPH...POST-TROP/INLAND 120H 26/1800Z...DISSIPATED $$ Forecaster Brown