922
FXUS63 KUNR 240438
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1038 PM MDT WED SEP 23 2026
KEY MESSAGES
- SOUTHWEST FLOW ALOFT EXPECTED THROUGH THE WEEKEND WITH
SHOWERS/THUNDERSTORMS POSSIBLE FRIDAY.
- UPPER TROUGH MOVES THROUGH FOR EARLY NEXT WEEK BRINGING
INCREASING PRECIPITATION CHANCES SUNDAY NIGHT ONWARD.
- TEMPERATURES WILL BE 5-10F ABOVE NORMAL THROUGH THE WEEKEND AND
THEN BACK TO SEASONAL READINGS EARLY NEXT WEEK.
UPDATE
ISSUED AT 1038 PM MDT WED SEP 23 2026
LINGERING SHOWERS AND AN ISOLATED THUNDERSTORM WILL CONTINUE
TONIGHT ACROSS PORTIONS OF THE CENTRAL SOUTH DAKOTA PLAINS.
OTHERWISE, CONDITIONS WILL CONTINUE TO CLEAR OUT FROM WEST TO
EAST. A FEW PATCHES OF FOG CANNOT BE RULED OUT IN FAR EASTERN
PORTIONS OF OUR CWA, ALTHOUGH SUPPORT AMONG THE GUIDANCE IS PRETTY
LIMITED. REWORKED POPS/QPF OVERNIGHT AND THURSDAY, BUT NO OTHER
SIGNIFICANT FORECAST CHANGES WERE NEEDED.
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 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1021 PM MDT WED SEP 23 2026
SOME PATCHY LIGHT FOG MAY BE POSSIBLE CLOSER TO CENTRAL SD, BUT
FOR THE TAF SITES VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
UPDATE...KSMITH
DISCUSSION...HELGESON
AVIATION...DYE
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