054
WTPZ41 KNHC 050858
TCDEP1
TROPICAL STORM PRISCILLA DISCUSSION NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL EP162025
200 AM MST SUN OCT 05 2025
PRISCILLA IS STRENGTHENING. THE STORM IS PRODUCING VERY DEEP
CONVECTION, WITH COLDEST CLOUD TOPS OF NEAR -80 DEG C, OVER THE
SOUTHERN AND WESTERN PORTION OF THE CIRCULATION AND CONVECTIVE
BANDING FEATURES ARE BECOMING BETTER DEFINED. THE ADVISORY
INTENSITY IS SET AT 55 KT BASED ON SUBJECTIVE DVORAK T-NUMBERS FROM
TAFB AND SAB, ALONG WITH ASCAT OBSERVATIONS.
SINCE THE CENTER IS STILL NOT VERY CLEARLY-DEFINED, THE INITIAL
MOTION ESTIMATE IS A SOMEWHAT UNCERTAIN 325/4 KT. STEERING
CURRENTS REMAIN WEAK OVER THE AREA, AND THERE MAY BE SOME SHIFTS IN
THE CENTER POSITION DUE TO RE-ORGANIZATION OF THE SYSTEM.
NONETHELESS, PRISCILLA IS EXPECTED TO MOVE ON THE WESTERN SIDE OF A
RIDGE OVER NORTHWESTERN MEXICO AND THE SOUTHEASTERN SIDE OF A
MID-LEVEL TROUGH OFF THE CALIFORNIA COAST. THIS SHOULD RESULT IN A
GENERALLY NORTHWESTWARD TRACK WITH SOME INCREASE IN FORWARD SPEED
DURING THE NEXT FEW DAYS. THE CROSS-TRACK MODEL SPREAD INCREASES
GREATLY AT DAYS 3-5. THIS IS LIKELY RELATED TO DIFFERENCES IN
THE AMPLITUDE OF THE UPPER TROUGH OFF THE U.S. WEST COAST, AND THE
STRENGTH AND POSITIONING OF THE RIDGE OVER NORTHERN MEXICO DURING
THIS PERIOD. THE OFFICIAL TRACK FORECAST IS CLOSE TO THE PREVIOUS
ONE AND IS ON THE NORTHERN SIDE OF THE GUIDANCE SUITE.
PRISCILLA IS OVER VERY WARM WATERS AND WITHIN A HIGHLY MOIST LOW-
TO MID-LEVEL AIR MASS. THESE CONDITIONS ARE CONDUCIVE FOR
SIGNIFICANT STRENGTHENING. HOWEVER, MODERATE EASTERLY SHEAR IS
EXPECTED TO PREVAIL OVER THE SYSTEM DURING THE NEXT FEW DAYS, WHICH
COULD AT LEAST PARTIALLY COUNTERACT THE OTHERWISE CONDUCIVE FACTORS
FOR INTENSIFICATION. THE OFFICIAL INTENSITY FORECAST IS ABOUT THE
SAME AS THE PREVIOUS ONE AND ON THE HIGH SIDE OF THE MODEL
INTENSITY GUIDANCE ENVELOPE.
KEY MESSAGES:
1. TROPICAL STORM CONDITIONS ARE POSSIBLE ALONG PORTIONS OF THE
COAST OF SOUTHWESTERN MEXICO WITHIN THE WATCH AREA TODAY AND
MONDAY. INTERESTS IN THE SOUTHERN PORTION OF BAJA CALIFORNIA SUR
SHOULD MONITOR THE PROGRESS OF PRISCILLA.
2. HEAVY RAINFALL ASSOCIATED WITH PRISCILLA WILL IMPACT COASTAL
SECTIONS OF SOUTHWESTERN MEXICO THROUGH MONDAY, WHICH COULD RESULT
IN FLASH FLOODING, PARTICULARLY IN AREAS OF HIGHER TERRAIN.
3. SWELLS GENERATED BY PRISCILLA ARE AFFECTING PORTIONS OF
THE COAST OF SOUTHWESTERN MEXICO AND WILL REACH THE COASTS OF
WEST-CENTRAL MEXICO AND THE SOUTHERN BAJA CALIFORNIA PENINSULA BY
MONDAY. THESE SWELLS ARE LIKELY TO CAUSE LIFE-THREATENING SURF AND
RIP CURRENT CONDITIONS.
FORECAST POSITIONS AND MAX WINDS
INIT 05/0900Z 16.1N 106.9W 55 KT 65 MPH
12H 05/1800Z 16.6N 107.2W 65 KT 75 MPH
24H 06/0600Z 17.1N 107.6W 70 KT 80 MPH
36H 06/1800Z 18.0N 108.4W 75 KT 85 MPH
48H 07/0600Z 18.9N 109.4W 80 KT 90 MPH
60H 07/1800Z 19.7N 110.7W 80 KT 90 MPH
72H 08/0600Z 20.5N 112.0W 80 KT 90 MPH
96H 09/0600Z 22.3N 114.5W 70 KT 80 MPH
120H 10/0600Z 24.7N 116.9W 50 KT 60 MPH
FORECASTER PASCH
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