118
FXUS63 KUNR 270454
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1054 PM MDT TUE AUG 26 2025
KEY MESSAGES
- SEASONABLY WARM THIS WEEK.
- AN ISOLATED SHOWER OR STORM POSSIBLE OVER THE BLACK HILLS
THROUGH EARLY THIS EVENING AND AGAIN WEDNESDAY AFTERNOON.
- INCREASING CHANCES FOR SHOWERS AND STORMS ACROSS THE AREA FOR
THE END OF WEEK INTO THE WEEKEND (50-70% FRIDAY AND SATURDAY).
DISCUSSION
(THIS EVENING THROUGH TUESDAY)
ISSUED AT 223 PM MDT TUE AUG 26 2025
THE UPPER-LEVEL RIDGE AXIS JUST TO THE WEST OF THE AREA, WILL DRIFT
EASTWARD AS IT BECOME NEARLY OVERHEAD INTO WEDNESDAY MORNING WHILE
DAMPENING A BIT. THE RIDGING ALOFT WILL ALLOW TEMPERATURES TO
WARM TO OR MAYBE SLIGHTLY ABOVE NORMAL THROUGH THAT TIME PERIOD.
FOR COMPARISON, "NORMAL" HIGH TEMPERATURES ARE RIGHT AROUND THE
MID 80S IN RAPID CITY AND GILLETTE.
THE FLOW WILL FLATTEN FOR THE END OF THE WEEK INTO NEXT WEEKEND AS
MORE OF A TROUGHING PATTERN TAKES PLACE OVER THE WEST COAST.
MOISTURE WILL INCREASE ON THE WEST SIDE OF THE RIDGE, AS MONSOONAL
MOISTURE DRIFTS NORTHWARD ON SOUTHWESTERLY FLOW WEDNESDAY AFTERNOON
THROUGH THURSDAY NIGHT BEFORE BECOMING MORE ZONAL/WESTERLY INTO THE
WEEKEND. THE COMBINATION OF INCREASED MOISTURE AND A SERIES OF
DISTURBANCES PASSING THROUGH THE AREA, WILL LEAD TO INCREASING
CHANCES FOR SHOWERS AND STORMS. THERE WILL BE ENOUGH INSTABILITY IN
PLACE FOR THUNDERSTORMS; HOWEVER, SHEAR VALUES REMAIN FAIRLY LIGHT
AND THE LACK OF ANY JET STREAM ENERGY THROUGH THE WEEKEND WILL LIMIT
ANY WIDESPREAD SEVERE WEATHER THREAT. PRECIPITABLE WATER VALUES
INCREASE TO AROUND 1-1.25 INCHES, WHICH IS AROUND 125% OF NORMAL FOR
THIS TIME OF YEAR. THE INCREASED MOISTURE LEVELS COULD LEAD TO
HEAVIER DOWNPOURS FORM ANY THUNDERSTORMS FRIDAY AND POSSIBLY INTO
SATURDAY.
SUNDAY THROUGH THE FIRST PART OF NEXT WEEK WILL SEE AN UPPER-LEVEL
RIDGE AXIS SLIDE DIRECTLY OVERHEAD ONCE AGAIN, ALLOWING FOR A
DECREASE IN PRECIPITATION CHANCES THROUGH THAT TIME PERIOD.
TEMPERATURES WILL ALSO WARM UP ACROSS THE AREA AGAIN, WITH HIGHS
REACHING THE MID TO POSSIBLY UPPER 80S. THIS WILL LIKELY BE SHORT-
LIVED AS LONG RANGE GUIDANCE IS TRENDING TOWARD ANOTHER TROUGH
DIGGING ACROSS THE AREA BY THE MIDDLE TO END OF NEXT WEEK.
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1054 PM MDT TUE AUG 26 2025
VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD. SCATTERED
THUNDERSTORMS WILL BE POSSIBLE ACROSS THE AREA WEDNESDAY AFTERNOON
AND EVENING.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION/KEY MESSAGES...COOLEY
AVIATION...13
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