000 WTPZ44 KNHC 232035 TCDEP4 Hurricane Willa Discussion Number 15 NWS National Hurricane Center Miami FL EP242018 300 PM MDT Tue Oct 23 2018 Willa's earlier eyewall replacement cycle appears to have finally ended with the erosion of the small inner eye and the outer eye becoming better defined in microwave data. The eye has also warmed and become more evident in infrared and visible satellite imagery this afternoon. The Air Force Reserve reconnaissance aircraft that flew into Willa earlier today measured a peak 700-mb flight-level wind of 109 kt in the southeast quadrant and SFMR winds of around 100 kt. Since the aircraft was only able to perform a single pass through each quadrant, there is likely some undersampling so the initial wind speed is set at 105 kt. Satellite and the earlier aircraft fixes show that Willa is moving a little faster toward the north-northeast, or around 030/9 kt. The hurricane is expected to accelerate northeastward ahead of a shortwave trough that is passing near the Baja California peninsula. The dynamical model guidance is in good agreement in showing that the center of Willa will reach the coast of west-central Mexico very soon, and then track inland over central Mexico tonight and Wednesday. The track guidance envelope has not changed much this cycle, and no significant changes were needed to the previous official track. Although the satellite presentation of Willa has improved somewhat this afternoon, little change in strength is expected before the hurricane reaches the coast of Mexico. Increasing southwesterly shear and the mountainous terrain of mainland Mexico will cause Willa to rapidly weaken after it moves inland tonight and Wednesday. A 24-h forecast point is provided for continuity, but it is unlikely that the low-level circulation will survive its passage over the mountainous terrain for that long of a time period. Key Messages: 1. Life-threatening storm surge is occurring along the coasts of the Isla Marias, and along the coast of southern Sinaloa and Nayarit states in west-central and southwestern Mexico near the path of Willa. 2. Damaging and life-threatening hurricane-force winds will reach the coast of west-central Mexico within the hurricane warning area within the next few hours. Hurricane-force winds will also extend inland across the mountainous areas of west-central Mexico as Willa moves inland. 3. Heavy rainfall from Willa is likely to produce life-threatening flash flooding and landslides over much of southwestern and west-central Mexico. FORECAST POSITIONS AND MAX WINDS INIT 23/2100Z 22.2N 106.4W 105 KT 120 MPH 12H 24/0600Z 23.7N 104.7W 50 KT 60 MPH...INLAND 24H 24/1800Z 25.7N 101.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 36H 25/0600Z...DISSIPATED $$ Forecaster Brown