127
WTPZ41 KNHC 080238
TCDEP1
HURRICANE PRISCILLA DISCUSSION NUMBER 14
NWS NATIONAL HURRICANE CENTER MIAMI FL EP162025
800 PM MST TUE OCT 07 2025
WHILE PRISCILLA REMAINS A LARGE AND FORMIDABLE HURRICANE, ITS
SATELLITE STRUCTURE IS STARTING TO SHOW SIGNS OF DECAY. THE EYEWALL
CLOUD TOP TEMPERATURES HAVE WARMED OVER THE PAST 3-6 HOURS, AND THE
LAST SEVERAL MICROWAVE PASSES SHOW THAT THE EYE IS NOW OPEN TO THE
NORTH. SOME OF THESE CHANGES COULD BE DUE TO OCEAN UPWELLING, WHICH
THE HURRICANE-REGIONAL MODELS HAVE BEEN FORECASTING TO OCCUR IN THE
RELATIVELY SHALLOW WARM WATERS THE LARGE HURRICANE HAS BEEN
TRAVERSING THROUGH. WHILE BOTH TAFB AND SAB DVORAK CI ESTIMATES WERE
CONSTRAINED AT T5.5/102-KT, THEIR DATA-T NUMBERS HAVE DECLINED, AND
BASED ON THE FURTHER DEGRADATION ON SATELLITE IMAGERY SINCE THAT
TIME, THE INITIAL INTENSITY IS BEING SET TO 90 KT FOR THIS ADVISORY,
WHICH IS ON THE LOWER END OF THE INTENSITY ESTIMATES.
PRISCILLA HAS RESUMED A MORE NORTHWESTWARD MOTION, ESTIMATED AT
310/8 KT. THE TRACK PHILOSOPHY REMAINS UNCHANGED, WITH A
NORTHWESTWARD MOTION AT A SIMILAR PACE EXPECTED TO CONTINUE FOR THE
NEXT COUPLE OF DAYS AS A MID-LEVEL RIDGE REMAINS IN PLACE TO THE
NORTHEAST OF THE HURRICANE. THE RIDGING THEN BECOMES ERODED AND
SHIFTED EAST AS A SHORTWAVE TROUGH, CURRENTLY OVER BRITISH COLUMBIA,
DIGS IN SOUTHWARD AND ULTIMATELY CUTS OFF JUST OFFSHORE OF THE
WESTERN U.S. COASTLINE. THIS SYNOPTIC EVOLUTION WILL LIKELY CAUSE
PRISCILLA TO TURN NORTHWARD FROM 48-72 HOURS. HOWEVER, THE CYCLONE
WILL ALSO BECOME MORE VERTICALLY SHALLOW AND MAY NOT FEEL THE FULL
EFFECTS OF THE EVOLVING MID-LEVEL STEERING, ULTIMATELY SLOWING DOWN
SUBSTANTIALLY BY THE END OF THE FORECAST. THE TRACK GUIDANCE THIS
CYCLE HAS SHIFTED A LITTLE RIGHTWARD, WITH THE GOOGLE DEEPMIND
ENSEMBLE MEAN (GDMI) AID A NOTABLE RIGHTWARD OUTLIER. THE NHC TRACK
WAS ADJUSTED A LITTLE RIGHT, BUT NOT AS FAR RIGHT AS GDMI, STAYING
BETWEEN IT AND THE RELIABLE HFIP CORRECTED CONSENSUS APPROACH (HCCA)
AID. IT IS WORTH NOTING THERE IS QUITE A BIT OF ALONG TRACK SPREAD
IN THE ENSEMBLE GUIDANCE IN 48-72 H, SO THE FORWARD MOTION AT THE
END OF THE FORECAST TRACK IS MORE UNCERTAIN THAN USUAL.
THE HURRICANE APPEARS PAST ITS PEAK TONIGHT WITH THE RECENT
STRUCTURAL DECLINE ON SATELLITE IMAGERY. WHILE SHIPS GUIDANCE
INDICATES SEA-SURFACE TEMPERATURES (SSTS) UNDER THE HURRICANE SHOULD
BE IN THE 28 C RANGE, THE HAFS-A/B AND HWRF SSTS FORECAST OUTPUT
SUGGESTS THE LARGE HURRICANE HAS UPWELLED MUCH COOLER OCEAN WATERS
THAT MAY TAKE SEVERAL DAYS FOR THE SATELLITE-BASED SST METHODS TO
PROPERLY DEPICT. WITH THIS IN MIND, THE NHC INTENSITY FORECAST IS
LOWER THAN THE PREVIOUS CYCLE, IN GOOD AGREEMENT WITH THE INTENSITY
AIDS, SHOWING STEADY WEAKENING OVER THE NEXT 2-3 DAYS AS PRISCILLA
MOVES INTO EVEN COOLER SSTS. SHEAR ALSO INCREASES QUICKLY OUT OF THE
SOUTHWEST BEYOND 48 HOURS, AND BOTH THE GFS/ECMWF SHOW PRISCILLA'S
REMAINING CONVECTION SHEARING OFF IN 72 H, WHICH WILL MARK WHEN THE
NHC FORECAST SHOWS PRISCILLA AS A REMNANT LOW NEAR TO THE CENTRAL
BAJA CALIFORNIA COASTLINE. THE GLOBAL MODELS SHOW THE REMNANT LOW
DISSIPATING SHORTLY THEREAFTER.
KEY MESSAGES:
1. TROPICAL STORM CONDITIONS ARE POSSIBLE ALONG THE BAJA CALIFORNIA
SUR PACIFIC COASTLINE WITHIN THE TROPICAL STORM WATCH AREA TONIGHT
INTO WEDNESDAY. INTERESTS ELSEWHERE IN THE BAJA CALIFORNIA PENINSULA
SHOULD MONITOR THE PROGRESS OF PRISCILLA.
2. RAINFALL ASSOCIATED WITH PRISCILLA WILL IMPACT PORTIONS OF BAJA
CALIFORNIA SUR INTO WEDNESDAY. MOISTURE ASSOCIATED WITH PRISCILLA
WILL LEAD TO HEAVY RAINFALL ACROSS WEST-CENTRAL MEXICO FROM TONIGHT
INTO THURSDAY MORNING AND ACROSS THE U.S. DESERT SOUTHWEST FROM
LATE THIS WEEK INTO THIS WEEKEND. THIS COULD RESULT IN FLASH
FLOODING, PARTICULARLY IN AREAS OF HIGHER TERRAIN.
3. SWELLS GENERATED BY PRISCILLA ARE AFFECTING PORTIONS OF THE
COAST OF SOUTHWESTERN AND WEST-CENTRAL MEXICO AS WELL AS THE COAST
OF THE SOUTHERN BAJA CALIFORNIA PENINSULA. 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 08/0300Z 20.6N 111.5W 90 KT 105 MPH
12H 08/1200Z 21.4N 112.4W 85 KT 100 MPH
24H 09/0000Z 22.6N 113.7W 70 KT 80 MPH
36H 09/1200Z 23.7N 114.7W 60 KT 70 MPH
48H 10/0000Z 24.9N 115.1W 45 KT 50 MPH
60H 10/1200Z 26.3N 115.3W 35 KT 40 MPH
72H 11/0000Z 27.4N 115.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 12/0000Z...DISSIPATED
FORECASTER PAPIN
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