025
WTPZ41 KNHC 051457 CCA
TCDEP1
TROPICAL STORM PRISCILLA DISCUSSION NUMBER 4...CORRECTED
NWS NATIONAL HURRICANE CENTER MIAMI FL EP162025
800 AM MST SUN OCT 05 2025
CORRECTED TYPO IN THE FIRST SENTENCE
AFTER THE LAST ADVISORY, A HELPFUL AMSR2 PASS REVEALED THAT
PRISCILLA REMAINS TILTED VERTICALLY NEAR ITS CORE, WITH THE
LOW-LEVEL CENTER ON 37 GHZ BEING LOCATED NORTH OF THE MID-LEVEL
CENTER SEEN ON 89 GHZ, WITH NO EVIDENCE OF AN EYE FEATURE SHOWING UP
YET. SOME OF THIS MISALIGNMENT COULD BE DUE TO 15-20 KT OF
NORTHEASTERLY SHEAR AFFECTING THE TROPICAL STORM. THE 12 UTC
SUBJECTIVE DVORAK FIXES FROM TAFB AND SAB WERE BOTH T4.0/65-KT, BUT
GIVEN THE EARLIER AMSR2 STRUCTURE, THE INITIAL INTENSITY IS BEING
HELD AT 55 KT THIS ADVISORY, CLOSER TO THE LOWER ADT AND SATCON
INTENSITY ESTIMATES.
PRISCILLA DOES NOT APPEAR TO BE IN A HURRY TO MOVE ANYWHERE, WITH
THE LATEST ESTIMATED MOTION ESSENTIALLY A NORTH-NORTHWEST DRIFT AT
330/3 KT. THE LACK OF MUCH FORWARD MOTION IS RELATED TO WEAKER THAN
USUAL MID-LEVEL RIDGING PLACED TO ITS NORTH, WHICH HAS BEEN ERODED
BY A LARGER MID- TO UPPER-LEVEL TROUGH CURRENTLY OVER THE WESTERN
GULF AND TEXAS. THIS FEATURE IS EXPECTED TO LIFT NORTH AND 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.
AS MENTIONED PREVIOUSLY, THE CROSS-TRACK SPREAD IN THE TRACK
GUIDANCE INCREASES AFTER THIS POINT, RELATED TO A DIGGING
UPPER-LEVEL TROUGH OFF THE U.S. WEST COAST THAT WILL ERODE THE RIDGE
ONCE AGAIN. THE TRACK GUIDANCE OVERALL IS A BIT SLOWER THAN THE
PREVIOUS CYCLE, AND THE NHC TRACK FORECAST WAS ALSO ADJUSTED SLOWER,
BUT STILL ALONG THE PREVIOUS FORECAST TRACK, CLOSE TO THE HCCA AND
GDMI TRACK AIDS.
WHILE PRISCILLA IS PRODUCING A LOT OF VERY DEEP CONVECTION, WITH
TOPS AS COLD AT -80 TO -85C, IT DOES NOT APPEAR TO BE RIGHT OVER THE
CENTER, BUT RATHER DISPLACED SOUTH DUE TO THE TROPICAL CYCLONE'S
CURRENT TILT. THIS STRUCTURE COULD ALSO BE CAUSING SOME DRY AIR TO
BE INGESTED INTO THE SYSTEM'S CORE, RESULTING IN THIS SHORT-TERM
HICCUP IN INTENSIFICATION. SINCE PRISCILLA'S LARGE-SCALE ENVIRONMENT
REMAINS MOIST, IT IS ASSUMED THAT THE STORM WILL MIX OUT THIS DRY
AIR AND SOON RESUME STRENGTHENING, LIKELY BECOMING A HURRICANE
BEFORE THE END OF THE DAY. HOWEVER, NORTHEASTERLY VERTICAL WIND
SHEAR IS STILL EXPECTED TO REMAIN BETWEEN 15-20 KT OVER THE NEXT
36-48 HOURS, AND THAT COULD TEMPER A FASTER RATE OF INTENSIFICATION
THAN SHOWN IN THE NHC INTENSITY FORECAST. NONE THE LESS, A PEAK OF
85 KT IS A LITTLE HIGHER THAN THE PRIOR CYCLE, FOLLOWING THE TRENDS
IN THE INTENSITY GUIDANCE. THERE IS SOME SPREAD IN THE
HURRICANE-REGIONAL MODEL GUIDANCE, WITH BOTH HAFS-A/B SHOWING A
HIGHER PEAK INTENSITY THAN THE HWRF/HMON RUNS. THE LATEST INTENSITY
FORECAST OPTS TO SPLIT THE DIFFERENCE, AND LIES NEAR THE LATEST HFIP
CORRECTED CONSENSUS AID. TOWARDS THE END OF THE FORECAST, THE SYSTEM
WILL BE MOVING OVER A SHARPLY COOLING SEA-SURFACE TEMPERATURE
GRADIENT, WHICH SHOULD INDUCE A WEAKENING TREND.
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 05/1500Z 16.4N 107.1W 55 KT 65 MPH
12H 06/0000Z 16.7N 107.2W 65 KT 75 MPH
24H 06/1200Z 17.4N 107.7W 70 KT 80 MPH
36H 07/0000Z 18.3N 108.6W 75 KT 85 MPH
48H 07/1200Z 19.2N 109.9W 80 KT 90 MPH
60H 08/0000Z 20.1N 111.1W 85 KT 100 MPH
72H 08/1200Z 21.0N 112.3W 85 KT 100 MPH
96H 09/1200Z 23.2N 115.0W 65 KT 75 MPH
120H 10/1200Z 25.1N 116.7W 40 KT 45 MPH
FORECASTER PAPIN
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