657
FXUS63 KUNR 252024
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
224 PM MDT MON AUG 25 2025
KEY MESSAGES
- SEASONABLY WARM THIS WEEK.
- MAINLY DRY THROUGH TUESDAY. AN ISOLATED SHOWER/STORM OVER THE
SOUTHERN BLACK HILLS AND NEAR THE NEBRASKA BORDER IN
SOUTHWEST/SOUTH CENTRAL SOUTH DAKOTA THROUGH TUESDAY MORNING.
- 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 MONDAY)
ISSUED AT 212 PM MDT MON AUG 25 2025
A FEW SHOWERS AND STORMS MAY LINGER INTO EARLY THIS EVENING NEAR THE
BLACK HILLS; HOWEVER, THEY WILL LIKELY BE LIMITED IN COVERAGE. LATER
IN THE EVENING AND OVERNIGHT, THE LLJ IS EXPECTED TO INCREASE WITH
AT LEAST WEAK CONVERGENCE ALONG AND SOUTH OF A LINE FROM ROUGHLY
CUSTER TO MELLETTE COUNTIES. THIS WILL ALLOW FOR A LOW CHANCE FOR
SHOWERS AND THUNDERSTORMS OVERNIGHT WITH AN INCREASE IN CLOUD COVER.
OVERALL MOISTURE REMAINS LIMITED, SO COVERAGE WILL LIKELY BE
ISOLATED TO SCATTERED AT BEST (15-20% CHANCE).
THE UPPER-LEVEL RIDGE AXIS JUST TO THE WEST OF THE AREA TODAY, WILL
DRIFT EASTWARD AS IT BECOME NEARLY OVERHEAD FOR TUESDAY INTO
WEDNESDAY. THE RIDGING ALOFT WILL ALLOW TEMPERATURES TO WARM TO OR
MAYBE SLIGHTLY ABOVE NORMAL THROUGH WEDNESDAY AFTERNOON. 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. A FEW STRONGER STORMS MAY DEVELOP
FRIDAY AFTERNOON AS A SHORTWAVE IS PROGGED TO PASS THROUGH DURING
THE HEATING OF THE DAY WITH INSTABILITY PUSHING AROUND 1000-1500
J/KG; HOWEVER, DEEP-LAYER SHEAR IS MARGINAL, AROUND 20-25KTS.
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z TUESDAY)
ISSUED AT 1138 AM MDT MON AUG 25 2025
ISOLATED CONVECTIVE SHOWERS ARE POSSIBLE OVER SOUTH CENTRAL SOUTH
DAKOTA THIS AFTERNOON. OTHERWISE VFR CONDITIONS WILL PREVAIL OVER
THE FORECAST AREA.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION/KEY MESSAGES...COOLEY
AVIATION...DYE
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