865
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
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