034
WTPZ42 KNHC 250245
TCDEP2
HURRICANE VANCE DISCUSSION NUMBER 15
NWS NATIONAL HURRICANE CENTER MIAMI FL EP222026
900 PM CST SAT OCT 24 2026
VANCE CONTINUES TO LOOK DISORGANIZED ON SATELLITE IMAGES, AND IT
SEEMS THAT SOUTHWESTERLY SHEAR IS KEEPING THE CONVECTION DISPLACED
FROM THE CENTER. THE HURRICANE IS ALSO MOVING OVER COOL WATERS,
WHICH IS ALSO INHIBITING INTENSIFICATION AS WELL. GPM MICROWAVE
IMAGES SHOW THAT THE STRUCTURE OF THE CYCLONE IS VERTICALLY TILTED
DUE TO THE AFOREMENTIONED SHEAR. DESPITE THE SYSTEM'S RAGGED
APPEARANCE, THE DVORAK INTENSITY ESTIMATE FROM TAFB IS STILL
T5.0/90 KT WHILE THE OBJECTIVE INTENSITY ESTIMATES ARE IN THE RANGE
OF 68-81 KT. THEREFORE, THE INITIAL INTENSITY HAS BEEN KEPT TO 80 KT
BASED ON A COMBINATION OF THAT DATA, HOWEVER, IT COULD BE GENEROUS.
THE INTENSITY FORECAST STILL HAS PLENTY OF UNCERTAINTIES. VANCE IS
GENERALLY EXPECTED TO WEAKEN DURING THE NEXT 12 H DUE TO THE
CONTINUOUS OF SHEAR WHILE IT REMAINS OVER COOL SSTS. AFTER THAT
TIME, THE HURRICANE'S INTENSITY COULD FLUCTUATE WHEN VANCE MOVES
OVER WARMER WATERS, BUT THE WIND SHEAR WILL LIKELY REMAIN ELEVATED.
AFTER 48 H, THE WIND SHEAR IS EXPECTED TO INCREASE EVEN FURTHER AND
THAT SHOULD RESULT IN A GRADUAL WEAKENING TREND. IT IS POSSIBLE
THAT VANCE COULD WEAKEN MORE THAN FORECAST GIVEN THE EXPECTED
INCREASING SHEAR AND INTRUSIONS OF DRY AIR. THE NHC INTENSITY
FORECAST IS GENERALLY SIMILAR TO THE PREVIOUS ONE WITH ONLY A FEW
MINOR ADJUSTMENTS MADE.
THE INITIAL MOTION REMAINS SLOWLY NORTH-NORTHWESTWARD OR 340/4 KT.
THE CYCLONE IS CURRENTLY BEING STEERED BY A WEAK LOW- TO MID-LEVEL
RIDGE OVER EASTERN MEXICO, AND IT IS MOVING TOWARD A LARGE
MID-LATITUDE TROUGH OVER THE WESTERN UNITED STATES AND NORTHWESTERN
MEXICO. VANCE SHOULD MOVE INTO AN AREA WHERE THE STEERING CURRENTS
ARE LIGHT, THUS THE HURRICANE IS EXPECTED TO MOVE EVEN SLOWER OVER
THE NEXT FEW DAYS. THE LATEST GUIDANCE SHIFTED SIGNIFICANTLY TO THE
WEST COMPARED TO THE PREVIOUS FORECAST, INCLUDING THE HIGHLY SKILLED
FORECAST AIDS HCCA AND GDMI, WHICH HAS ADDED SOME UNCERTAINTY IN THE
TRACK FORECAST. THE NEW TRACK FORECAST WAS ADJUSTED SLIGHTLY TO THE
WEST AND IS A LITTLE SLOWER THAN THE PREVIOUS ONE. HOWEVER, THE
CURRENT TRACK IS ON THE EASTERN SIDE OF THE GUIDANCE ENVELOPE, AND
ADDITIONAL ADJUSTMENTS TO THE WEST COULD BE NEEDED.
KEY MESSAGES:
1. DUE TO THE UNCERTAINTIES IN BOTH THE TRACK AND INTENSITY
FORECASTS, IT IS TOO EARLY TO SAY WHAT WIND AND STORM SURGE
IMPACTS VANCE MAY CAUSE ALONG THE COAST OF MEXICO. INTERESTS IN
SOUTHWESTERN MEXICO SHOULD CONTINUE TO MONITOR THE PROGRESS OF THE
HURRICANE.
2. HEAVY RAINFALL ASSOCIATED WITH SLOW-MOVING HURRICANE VANCE WILL
IMPACT THE WESTERN COAST OF MEXICO FROM MICHOACáN TO JALISCO DURING
MUCH OF NEXT WEEK. THIS RAINFALL MAY PRODUCE LIFE-THREATENING
FLOODING AND MUDSLIDES ACROSS COLIMA AND WESTERN PORTIONS OF
MICHOACáN AND JALISCO, ESPECIALLY IN AREAS ALONG STEEP TERRAIN.
FORECAST POSITIONS AND MAX WINDS
INIT 25/0300Z 13.7N 103.4W 80 KT 90 MPH
12H 25/1200Z 14.2N 103.7W 70 KT 80 MPH
24H 26/0000Z 15.1N 104.2W 70 KT 80 MPH
36H 26/1200Z 15.6N 104.6W 70 KT 80 MPH
48H 27/0000Z 16.1N 104.8W 70 KT 80 MPH
60H 27/1200Z 16.5N 105.0W 65 KT 75 MPH
72H 28/0000Z 17.3N 105.2W 55 KT 65 MPH
96H 29/0000Z 18.4N 105.6W 45 KT 50 MPH
120H 30/0000Z 19.6N 106.1W 35 KT 40 MPH
FORECASTER KATZ/CANGIALOSI
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