453
WTPZ41 KNHC 052042
TCDEP1
HURRICANE PRISCILLA DISCUSSION NUMBER 5
NWS NATIONAL HURRICANE CENTER MIAMI FL EP162025
200 PM MST SUN OCT 05 2025
PRISCILLA HAS BECOME MARKEDLY BETTER ORGANIZED THIS AFTERNOON. A
WELL-DEFINED CURVED BAND HAS FORMED ALONG THE SOUTHERN SEMICIRCLE
OF THE TROPICAL CYCLONE, AND THERE HAVE BEEN OCCASIONAL HINTS OF A
RAGGED EYE SHOWING UP ON THE VISIBLE IMAGES. A SCATTEROMETER PASS
AT 1713 UTC SHOWED THE CIRCULATION HAS BECOME BETTER EMBEDDED IN
THE CENTRAL DENSE OVERCAST, THOUGH THERE HAVEN'T BEEN ANY RECENT
HIGH-RESOLUTION MICROWAVE IMAGES TO CONFIRM THAT PRISCILLA IS BETTER
VERTICALLY ALIGNED. SUBJECTIVE DVORAK FIXES FROM SAB AND TAFB STILL
SUPPORT T4.0/65 KT, AND THE OBJECTIVE ESTIMATES FROM UW-CIMSS ARE
ALSO INCREASING, NOW IN THE 59-66 KT RANGE. THUS, THE INITIAL
INTENSITY IS BEING INCREASED TO 65 KT, MAKING PRISCILLA THE 10TH
HURRICANE OF THE 2025 EASTERN PACIFIC SEASON. WIND RADII WERE ALSO
ADJUSTED BASED ON THE EARLIER SCATTEROMETER DATA.
THE HURRICANE CONTINUES TO MOVE VERY SLOWLY, WITH A BEST GUESS AT AN
ESTIMATED MOTION OF 330/3 KT. THERE ISN'T MUCH CHANGE TO THE TRACK
REASONING, WITH THE CURRENT LACK OF MOTION MAINLY DUE TO LIGHT
STEERING CURRENTS FROM A WEAK RIDGE ERODED BY A LARGER MID- TO
UPPER-LEVEL TROUGH OVER THE WESTERN GULF AND TEXAS. THIS FEATURE IS
EXPECTED TO LIFT OUT, ALLOWING THE RIDGING OVER MEXICO TO GRADUALLY
BECOME RE-ESTABLISHED. THE END RESULT SHOULD CAUSE PRISCILLA TO
GRADUALLY ACCELERATE TO THE NORTH-NORTHWEST WITH A SUBTLE BEND
LEFTWARD OVER THE NEXT 2-3 DAYS. THERE REMAINS A NOTABLE AMOUNT OF
SPREAD IN THE TRACK GUIDANCE IN 72 HOURS, WITH THE GFS CONTINUING TO
BE ON THE FAR SOUTH AND WEST SIDE OF THE GUIDANCE ENVELOPE, AND THE
ECMWF ON THE NORTH AND EAST SIDE. THE NHC TRACK FORECAST IS VERY
SIMILAR TO THE PRIOR ONE, SPLITTING THE DIFFERENCE BETWEEN THESE
OUTLIERS, AND LIES CLOSE TO A BLEND OF THE HCCA AND GDMI TRACK
AIDS.
SHEAR ANALYSIS FROM UW-CIMSS INDICATES THAT THE PRISCILLA IS
EXPERIENCING 20 KT OF EAST-NORTHEASTERLY SHEAR, AND YET THE CYCLONE
HAS BEEN ABLE TO INTENSIFY, LIKELY AIDED BY PLENTY WARM SEA-SURFACE
TEMPERATURES, AND AMPLE DEEP-LAYER MOISTURE. THE SHEAR IS EXPECTED
TO STAY ABOUT THE SAME IN MAGNITUDE OVER THE NEXT 2-3 DAYS, AND IN
GENERAL THE INTENSITY GUIDANCE HAS COME UP FROM THE PREVIOUS CYCLE.
SHIPS RAPID INTENSIFICATION (RI) INDICES ARE ELEVATED, AND IF
PRISCILLA CAN ESTABLISH A TIGHTER INNER CORE, IT IS NOT OUT THE
QUESTION THE HURRICANE COULD INTENSIFY MORE THAN SHOWN HERE. FOR
NOW, THE NHC INTENSITY FORECAST WILL SHOW MORE GRADUAL
INTENSIFICATION, ASSUMING THE SHEAR TEMPERS A FASTER RATE OF
DEEPENING, BUT NOW HAS PEAK OF 90 KT, A LITTLE HIGHER THAN
BEFORE. THIS IS A BIT HIGHER THAN THE HCCA INTENSITY AID, BUT LOWER
THAN SOME OF THE MORE AGGRESSIVE MODELS (HAFS-A/B, COAMPS-TC,
FLORIDA STATE SUPERENSEMBLE). AFTER 72 H, PRISCILLA IS FORECAST TO
MOVE OVER A SHARPLY COOLING SEA-SURFACE TEMPERATURE GRADIENT, WHICH
SHOULD INDUCE RAPID WEAKENING BY THE END OF THE FORECAST PERIOD.
KEY MESSAGES:
1. TROPICAL STORM CONDITIONS ARE POSSIBLE ALONG PORTIONS OF THE
COAST OF SOUTHWESTERN MEXICO WITHIN THE WATCH AREA THROUGH MONDAY.
INTERESTS IN THE SOUTHERN PORTION OF BAJA CALIFORNIA SUR SHOULD ALSO
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 05/2100Z 16.4N 107.1W 65 KT 75 MPH
12H 06/0600Z 16.8N 107.3W 70 KT 80 MPH
24H 06/1800Z 17.7N 108.1W 75 KT 85 MPH
36H 07/0600Z 18.6N 109.1W 80 KT 90 MPH
48H 07/1800Z 19.5N 110.4W 90 KT 105 MPH
60H 08/0600Z 20.4N 111.7W 90 KT 105 MPH
72H 08/1800Z 21.4N 113.0W 80 KT 90 MPH
96H 09/1800Z 23.6N 115.4W 60 KT 70 MPH
120H 10/1800Z 25.4N 116.6W 35 KT 40 MPH
FORECASTER PAPIN
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