670
WTPZ42 KNHC 251459
TCDEP2
HURRICANE VANCE DISCUSSION NUMBER 17
NWS NATIONAL HURRICANE CENTER MIAMI FL EP222026
900 AM CST SUN OCT 25 2026
STRONG WEST-SOUTHWESTERLY WIND SHEAR IS SIGNIFICANTLY IMPACTING
VANCE THIS MORNING. AN EARLIER WSF-M PASS INDICATED THAT THE
LOW-LEVEL CENTER WAS LOCATED FARTHER SOUTHWEST THAN PREVIOUSLY
ESTIMATED, AND THE INITIAL POSITION WAS ADJUSTED ACCORDINGLY. DEEP
CONVECTION NEAR THE MID-LEVEL CENTER CONTINUES TO DIMINISH, LEAVING
THE PARTIALLY EXPOSED LOW-LEVEL CENTER DISPLACED TO THE
SOUTHWEST. SUBJECTIVE DVORAK INTENSITY ESTIMATES CONTINUE TO
DECREASE AND NOW RANGE FROM 49-65 KT. THE INITIAL INTENSITY IS SET
AT A POTENTIALLY GENEROUS 65 KT FOR THIS ADVISORY.
THE HURRICANE IS MOVING NORTH-NORTHWESTWARD AROUND 6 KT BETWEEN A
MID-LEVEL RIDGE CENTERED OVER NORTHERN MEXICO AND SOUTHERN TEXAS AND
A STRONG, CLOSED UPPER-LEVEL LOW PROGRESSING ACROSS THE SOUTHWESTERN
UNITED STATES. VANCE IS EXPECTED TO MOVE TOWARD THE NORTHWEST OR
WEST-NORTHWEST AT A SLOWER FORWARD SPEED OVER THE NEXT COUPLE OF
DAYS AS STEERING CURRENTS WEAKEN. BY MIDWEEK, VANCE IS FORECAST TO
TURN TOWARD THE NORTH-NORTHWEST THEN NORTH AS IT WEAKENS AND BECOMES
INCREASINGLY STEERED BY THE LOW- TO MID-LEVEL FLOW. THE TRACK
FORECAST HAS BEEN SHIFTED TO THE LEFT FROM THE PREVIOUS ADVISORY TO
ACCOUNT FOR THE REVISED INITIAL POSITION AND CONTINUED LEFTWARD
TRENDS IN THE GLOBAL AND REGIONAL HURRICANE MODEL GUIDANCE. HOWEVER,
THIS TRACK STILL REMAINS ON THE EASTERN EDGE OF THE GUIDANCE AND
FURTHER WESTWARD ADJUSTMENTS MAY BE NECESSARY IN FUTURE FORECAST
CYCLES.
DESPITE MOVING OVER SLIGHTLY WARMER WATERS DURING THE NEXT SEVERAL
DAYS, SIGNIFICANT SOUTHWESTERLY TO WESTERLY WIND SHEAR AND
RELATIVELY DRY MID-LEVEL AIR ARE EXPECTED TO LEAD TO GRADUAL
WEAKENING. THE LATEST NHC FORECAST NOW CALLS FOR A FASTER RATE OF
WEAKENING THROUGH MIDWEEK THAN THE PREVIOUS ADVISORY. BY LATE THIS
WEEK, SIMULATED SATELLITE IMAGERY FROM THE ECMWF AND GFS SUGGESTS
THAT VANCE MAY STRUGGLE TO SUSTAIN ORGANIZED DEEP CONVECTION. THE
FORECAST NOW CALLS FOR VANCE TO BECOME POST-TROPICAL BY 96 H AND
DEGENERATE INTO A REMNANT LOW BY 120 H.
KEY MESSAGES:
1. DUE TO THE LARGE UNCERTAINTIES IN BOTH THE TRACK AND INTENSITY
FORECASTS, IT IS TOO EARLY TO DETERMINE WHAT, IF ANY, WIND AND STORM
SURGE IMPACTS VANCE COULD BRING TO THE COAST OF MEXICO. INTERESTS IN
SOUTHWESTERN MEXICO SHOULD CONTINUE TO MONITOR THE PROGRESS OF
VANCE.
2. PERIODS OF HEAVY RAINFALL ASSOCIATED WITH SLOW-MOVING HURRICANE
VANCE WILL IMPACT THE WESTERN COAST OF MEXICO FROM MICHOACáN TO
JALISCO DURING MUCH OF THIS WEEK. THIS RAINFALL MAY PRODUCE FLOODING
AND MUDSLIDES ACROSS COLIMA AND WESTERN PORTIONS OF MICHOACáN AND
JALISCO, ESPECIALLY IN AREAS ALONG STEEP TERRAIN.
FORECAST POSITIONS AND MAX WINDS
INIT 25/1500Z 14.3N 103.8W 65 KT 75 MPH
12H 26/0000Z 14.5N 104.1W 60 KT 70 MPH
24H 26/1200Z 15.0N 104.8W 60 KT 70 MPH
36H 27/0000Z 15.3N 105.4W 55 KT 65 MPH
48H 27/1200Z 16.1N 105.9W 50 KT 60 MPH
60H 28/0000Z 17.0N 106.3W 45 KT 50 MPH
72H 28/1200Z 18.0N 106.6W 45 KT 50 MPH
96H 29/1200Z 19.5N 107.0W 40 KT 45 MPH...POST-TROPICAL
120H 30/1200Z 21.4N 107.2W 30 KT 35 MPH...POST-TROP/REMNT LOW
FORECASTER ADAMS
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