326
FXUS63 KUNR 240017
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
108 PM MDT WED SEP 23 2026
KEY MESSAGES
- ISOLATED STRONG/SEVERE THUNDERSTORMS POSSIBLE THROUGH EARLY
THIS EVENING
- SOUTHWEST FLOW ALOFT EXPECTED THROUGH THE WEEKEND WITH
SHOWERS/THUNDERSTORMS POSSIBLE LATE THURSDAY/FRIDAY
- UPPER TROUGH MOVES THROUGH FOR EARLY NEXT WEEK BRING INCREASING
PRECIPITATION CHANCES SUNDAY NIGHT INTO EARLY NEXT WEEK
- TEMPERATURES WILL BE 5-10F ABOVE NORMAL THROUGH THE WEEKEND AND
THEN BACK TO SEASONAL READINGS EARLY NEXT WEEK
DISCUSSION
(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 100 PM MDT WED SEP 23 2026
18Z SURFACE ANALYSIS HAD WARM FRONT FROM WEAK LOW OVER SOUTHEAST
MT INTO EASTERN CO. AHEAD OF IT, QUITE A BIT OF CLOUD COVER
PERSISTS. BEHIND IT, CLEARING SKIES PER 0.5KM VISIBLE SATELLITE
LOOP. THESE FEATURES IN ASSOCIATION WITH SHORTWAVE TROUGH MOVING
ACROSS EASTERN MT/WESTERN ND PER WATER VAPOUR LOOP. 90KT STREAK
OVERHEAD. EFFECTS OF THESE FEATURES THE MAIN SHORT TERM FORECAST
CONCERN.
LATER THIS AFTERNOON/EVENING, EARLY FALL SOLAR INSOLATION SHOULD
ERASE MLCIN FROM THE 18Z KUDX SOUNDING WITH SURFACE TEMPERATURES
AROUND 80F NEEDED. ~1KJ/KG MLCAPE WILL BE AVAILABLE ALONG THE WARM
FRONT WITH 40KTS OF EFFECTIVE SHEAR UNDER JET STREAK. CONVECTION
SHOULD DEVELOP AFTER 21Z PER MOST CAMS WITH ISOLATED STRONG/SEVERE
THUNDERSTORMS POSSIBLE CREATING MARGINALLY SEVERE HAIL/WIND
GUSTS. ACTIVITY WILL MOVE EAST THIS EVENING WITH CLEARING SKIES
OVER THE CWA OVERNIGHT. TEMPERATURES WILL BE NEAR GUIDANCE.
SHORTWAVE RIDGING THURSDAY WILL BRING DRY WEATHER FOR MOST OF THE
CWA, BUT AFOREMENTIONED WARM FRONT GETS HUNG UP OVER THE SD/NE
BORDER WHICH MAY BE THE FOCUS FOR A FEW SHRA/TS. STRONGER WAVE
ARRIVES FRIDAY WITH INCREASING POPS, ESPECIALLY EAST OF THE BLACK
HILLS WHERE BEST LOW LEVEL MOISTURE RETURN/BUOYANCY FORECAST. DRY
SATURDAY AND MOST OF SUNDAY. TEMPERATURES WILL BE 5-10F ABOVE
NORMAL THROUGH THE WEEKEND. THEN, ENSEMBLE GUIDANCE PORTRAYS A
STRONG UPPER TROUGH SLICING ACROSS THE NORTHERN PLAINS WITH
INCREASING CHANCES OF PRECIPITATION AS WELL AS COOLER, MORE FALL-
LIKE TEMPERATURES.
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z FRIDAY)
ISSUED AT 613 PM MDT WED SEP 23 2026
A FEW SHOWERS AND STRONG THUNDERSTORMS ARE IN PROGRESS THIS EVENING
FROM THE NORTHERN BLACK HILLS NORTHEAST ACROSS THE NORTHWESTERN
SOUTH DAKOTA PLAINS, WITH THE POTENTIAL FOR BRIEF DROPS TO IFR CIGS
AND MVFR VSBYS, HAIL, AND GUSTY/ERRATIC WINDS AS HIGH AS 50KTS AS
THEY TRANSLATE EASTWARD. POTENTIAL BACK TO THE SOUTHWEST AS KRAP AND
KGCC IS TOO LOW TO WARRANT PROB30S. A FEW ADDITIONAL, WEAKER SHOWERS
AND STORMS WILL BE POSSIBLE ACROSS THE SOUTH-CENTRAL SOUTH DAKOTA
PLAINS AS WELL. HIGH-RES GUIDANCE GENERALLY CLEARS ALL OF THIS
ACTIVITY OUT OF THE REGION BY 06Z TONIGHT, EXCEPT PERHAPS KICR.
OUTSIDE OF STORMS, VFR CONDITIONS ARE EXPECTED ARE EXPECTED
THROUGHOUT THE FORECAST PERIOD INTO THURSDAY (HIGH CONFIDENCE FROM
MID-MORNING THURSDAY ONWARD). RH VALUES WILL BE A BIT MOIST
OVERNIGHT TONIGHT ACROSS OUR PLAINS EAST OF THE BLACK HILLS, BUT AT
THIS TIME THERE IS LITTLE TO NO SUPPORT IN THE GUIDANCE FOR ANY
BROAD DEVELOPMENT OF FOG OR LOW STRATUS. THURSDAY NIGHT,
SOUTH/SOUTHEAST WINDS WILL INCREASE AND BECOME A BIT GUSTY AT
KGCC...JUST BEYOND THE END OF THE CURRENT TAF PERIOD.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION...HELGESON
AVIATION...SMITH
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