ZCZC MIATCDEP4 ALL TTAA00 KNHC DDHHMM Hurricane Hilary Discussion Number 14 NWS National Hurricane Center Miami FL EP092023 300 PM MDT Sat Aug 19 2023 Hilary appears to be weakening quickly. The eye is filling and the cloud tops in the eyewall and rainbands have been warming during the past several hours. In addition, the hurricane has become increasingly asymmetric with dry air continuing to wrap into the western half of the circulation. The Air Force Hurricane Hunters have been investigating Hilary during the past few hours and found that the minimum pressure has risen to 959 mb. Blending the aircraft flight-level wind and SFMR data, as well as some of the satellite estimates yields an initial intensity of 95 kt, but that could be a little generous. Areas of heavy rain are already spreading across portions of the Baja California Peninsula and the Southwestern U.S. Hilary is also producing a large area of high seas along the coast of Baja California and the Gulf of California, with maximum significant wave heights estimated to be higher than 40 ft. The hurricane is still moving north-northwestward, or 345/15 kt. The steering currents are well established and consist of a strong mid-level high pressure area over the south-central U.S. and a mid- to upper-level low off the central California coast. The flow between these features should cause Hilary to accelerate to the north-northwest or north during the next day or two, with the core of the system reaching the central portion of the Baja California Peninsula tonight and southern California Sunday afternoon or evening. The NHC track forecast is largely the same as the previous one and near the middle of the guidance envelope. Users are reminded that the exact details of the track forecast, including where Hilary might make landfall, are of little overall importance since strong winds and heavy rainfall will extend far from the center. These hazards will also begin well in advance of the arrival of the center. Hilary is expected to continue weakening rather quickly while it moves northward due to significantly cooler waters, drier air, and an increase in vertical wind shear. However, Hilary is still expected to be a hurricane when it makes landfall or moves very near the central portion of the Baja California Peninsula. There is high confidence that Hilary will move into southern California as a tropical storm. KEY MESSAGES: 1. Preparations for flooding impacts should be completed as soon as possible, as heavy rainfall will begin well in advance of the center. In the Southwestern U.S., the potentially historic amount of rainfall is expected to cause flash, urban, and arroyo flooding including landslides, mudslides, and debris flows. Dangerous to locally catastrophic flooding impacts are expected late tonight through early Monday. 2. Hurricane conditions are expected along the west-central coast of the Baja California Peninsula within the hurricane warning area tonight and Sunday morning, and are possible in the Hurricane Watch area on Sunday. 3. Tropical storm conditions are expected to begin Sunday in portions of the southwestern U.S. within the Tropical Storm Warning area. Winds could be particularly strong and gusty in and near areas of higher terrain. Gusty winds are expected to spread well inland across the western U.S. 4. Large swells generated by Hilary will affect portions of the Baja California Peninsula and southern California over the next couple of days. These swells are likely to cause life-threatening surf and rip current conditions. FORECAST POSITIONS AND MAX WINDS INIT 19/2100Z 23.8N 114.1W 95 KT 110 MPH 12H 20/0600Z 26.4N 114.8W 80 KT 90 MPH 24H 20/1800Z 30.8N 116.2W 60 KT 70 MPH 36H 21/0600Z 36.4N 117.6W 35 KT 40 MPH...POST-TROP/INLAND 48H 21/1800Z...DISSIPATED $$ Forecaster Cangialosi NNNN