Issued at 200 PM MST Wed Oct 08 2025
421 WTPZ41 KNHC 082035 TCDEP1 Tropical Storm Priscilla Discussion Number 17 NWS National Hurricane Center Miami FL EP162025 200 PM MST Wed Oct 08 2025 The satellite presentation of Priscilla has fallen apart quickly over the past 18 hours. Over the past 6 hours, deep convection has gradually diminished. The latest CI numbers from TAFB and SAB are 65 kt, while objective intensity estimates from UW-CIMSS have decreased to the 47-53 kt range. An ASCAT-C pass from 1750 UTC showed peak vectors of 55 kt. Given the low bias due to the resolution of this instrument, the initial intensity is maintained at 60 kt. The initial motion estimate is northwestward, or 315 degrees at 7 kt. Priscilla is moving along the southwestern side of a mid-level high pressure ridge near the Texas/Mexico border. In 24-36 hours or so, a large trough or cutoff low near the California coast should induce a turn toward the north. By 48 hours, Priscilla will likely have weakened into a shallow cyclone moving in the low-level environmental flow. The latest NHC track forecast has been adjusted very slightly to the right of the previous official forecast, and lies close to the HFIP Corrected Consensus (HCCA) approach. Water temperatures along Priscilla's path are quickly decreasing. The cyclone is expected to cross the 26 degree C isotherm in about 12 hours. Priscilla is also moving into an increasingly dry environment. The GFS and ECMWF simulated satellite imagery show the storm losing its convection and degenerating to a remnant low in about 48 hours, but given how the convection looks now, it wouldn't be surprising if this occurred sooner. The global and regional models then show the remnant low dissipating by hour 72. There are no major changes to the NHC intensity forecast, which is near the middle of the guidance envelope. KEY MESSAGES: 1. Tropical storm conditions are possible along the Baja California Sur Pacific coastline within the Tropical Storm Watch area though this evening. Interests elsewhere in the Baja California peninsula should monitor the progress of Priscilla. 2. Moisture associated with Priscilla will lead to heavy rainfall and a flash flood risk across portions of Arizona, southern Utah, through the Four Corners into southwest Colorado and far northwest New Mexico from Thursday into Saturday. 3. Large swells generated by Priscilla are affecting the Pacific coast of Baja California Sur as well as portions of the coast of southwestern and west-central Mexico. These swells are likely to cause life-threatening surf and rip current conditions, in addition to some coastal flooding. FORECAST POSITIONS AND MAX WINDS INIT 08/2100Z 22.0N 113.0W 60 KT 70 MPH 12H 09/0600Z 22.8N 114.0W 50 KT 60 MPH 24H 09/1800Z 24.0N 114.8W 45 KT 50 MPH 36H 10/0600Z 25.3N 115.2W 40 KT 45 MPH 48H 10/1800Z 26.3N 115.3W 30 KT 35 MPH...POST-TROP/REMNT LOW 60H 11/0600Z 27.0N 115.1W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 11/1800Z...DISSIPATED $$ Forecaster Hagen
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