Issued at 200 AM MST Thu Oct 09 2025
000 WTPZ41 KNHC 090845 TCDEP1 Tropical Storm Priscilla Discussion Number 19 NWS National Hurricane Center Miami FL EP162025 200 AM MST Thu Oct 09 2025 Priscilla has been gradually losing its organized deep convection overnight. As a result, objective and subjective satellite intensity estimates have fallen, and the initial intensity is lowered to 45 kt for this advisory. While scatterometer data did not measure the core of the storm, it did show tropical-storm-force winds about 40 miles offshore of Baja California Sur. The wind radii have been adjusted accordingly. The estimated motion is northwestward at 7 kt. As Priscilla becomes a shallow vortex, it is expected to turn north-northwestward later this morning in the low-level flow. By Friday, the system should slow and drift northward, stalling off the coast of the Baja California Peninsula until the circulation opens into a trough. The storm has moved over the 26 degree C isotherm toward progressively cooler waters. Mid-level humidities are also falling, and vertical wind shear is forecast to increase substantially. These atmospheric and oceanic conditions should accelerate Priscilla's transition into a post-tropical cyclone. The latest NHC intensity forecast now calls for Priscilla to become a post-tropical cyclone in 24 hours and dissipate off the coast of Baja California in a couple of days or so. KEY MESSAGES: 1. Tropical storm conditions are possible along the Baja California Sur Pacific coastline within the Tropical Storm Watch area for the next several hours. 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 through 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 09/0900Z 23.3N 114.1W 45 KT 50 MPH 12H 09/1800Z 24.3N 114.8W 40 KT 45 MPH 24H 10/0600Z 25.5N 115.1W 35 KT 40 MPH...POST-TROPICAL 36H 10/1800Z 26.4N 115.2W 30 KT 35 MPH...POST-TROP/REMNT LOW 48H 11/0600Z 27.0N 114.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 60H 11/1800Z...DISSIPATED $$ Forecaster Bucci
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