Issued at 800 AM MST Thu Oct 09 2025
000 WTPZ41 KNHC 091441 TCDEP1 Tropical Storm Priscilla Discussion Number 20 NWS National Hurricane Center Miami FL EP162025 800 AM MST Thu Oct 09 2025 Infrared and water vapor satellite imagery shows that Priscilla continues to lose deep convection with warming cloud tops. Water vapor imagery shows that drier air has wrapped into the inner core, with only limited convection remaining in outer rainbands. Satellite intensity estimates have continued to decrease, and the initial intensity is lowered to 40 kt for this advisory. Priscilla is moving north-northwestward at an estimated motion of 330/7 kt. As the system continues to spin down and become a shallow vortex, a turn toward the north and eventually north-northeast within the low-level flow is anticipated. The storm is expected to slow down, stall, and dissipate offshore the west coast of Baja California. Sea surface temperatures continue to cool along the track of Priscilla, with drier mid-level air mixing into the center. A weakening trend is likely to continue and Priscilla is anticipated to struggle to produce organized convection. This should result in Priscilla becoming a post-tropical cyclone within 24 hours. Although, if current trends continue with waning convection Priscilla could become a post-tropical remnant low earlier than forecast. The latest NHC intensity forecast follows these latest trends in the global model suite, and lies near the middle of the guidance envelope. Remnant moisture associated with Priscilla remains the primary hazard associated with the system across portions of Southwestern United States. Heavy rainfall and flash flooding is likely into the weekend over portions of central Arizona, with scattered areas of flash flooding expected across the remainder of Arizona, southern Utah, southwest Colorado, and far northwest New Mexico. Please follow forecast updates from local National Weather Service forecast offices in the southwest U.S. at weather.gov and the Weather Prediction Center at wpc.ncep.gov KEY MESSAGES: 1. Moisture associated with Priscilla will lead to a significant heavy rainfall and a flash flood risk across portions of Arizona, southern Utah, southwest Colorado, and far northwest New Mexico through Saturday. 2. 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 09/1500Z 23.8N 114.7W 40 KT 45 MPH 12H 10/0000Z 24.8N 115.1W 35 KT 40 MPH 24H 10/1200Z 25.9N 115.3W 30 KT 35 MPH...POST-TROPICAL 36H 11/0000Z 26.7N 115.2W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 11/1200Z 27.3N 114.8W 20 KT 25 MPH...POST-TROP/REMNT LOW 60H 12/0000Z...DISSIPATED $$ Forecaster Kelly
