620
FXUS63 KUNR 211110
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
510 AM MDT SUN JUN 21 2026
KEY MESSAGES
- BENEFICIAL RAINFALL EXPECTED THROUGH SUNDAY.
- COOLER TEMPERATURES FOR SUNDAY THROUGH TUESDAY, THEN A GRADUAL
WARM UP FOR THE REST OF NEXT WEEK.
UPDATE
ISSUED AT 942 PM MDT SAT JUN 20 2026
KUDX RADAR SHOWS A LINE OF THUNDERSTORMS OVER JACKSON AND BENNETT
COUNTIES MOVING EASTWARD TOWARD THE SOUTH CENTRAL SD COUNTIES. THESE
STORMS HAVE BEEN PRODUCING GUSTY WINDS UNDER 40 MPH AND SMALL HAIL
AND SHOULD EXIT THE AREA IN THE NEXT FEW HOURS. THESE STORMS ARE
EXPECTED TO REMAIN BELOW SEVERE LIMITS, ESPECIALLY AS IT SHIFTS
EASTWARD TOWARD MORE STABLE AIR. WATER VAPOR IMAGERY SHOWS THE
SERIES OF UPPER WAVES STILL CROSSING NEAR THE MT/WY BORDER
APPROACHING THE FORECAST AREA. THERE IS STILL GOOD AGREEMENT THAT
MORE SHOWERS (AND ISO T) WILL DEVELOP OVERNIGHT...PRIMARILY ACROSS
THE NW TO CENTRAL SD PLAINS WHERE QPF TOTALS COULD GENERALLY RANGE
FROM 0.10-0.50" BY 12Z...WITH SOME SPOTS OVER HALF AN INCH. COULD
ALSO SEE OVERNIGHT FOG ACROSS THE PARTS EASTERN FOOTHILLS. CHANCES
FOR SHOWERS WILL CONTINUE THROUGH SUNDAY ACROSS THE CWA AS AN 850MB
LOW DEVELOPS NEAR THE SD/NE BORDER. COOL, EASTERLY FLOW ACROSS THE
NORTHERN TWO-THIRDS OF THE STATE WILL KEEP SHOWERS GOING THROUGH THE
DAY...WHILE HIGHER THETA E/INSTABILITY SOUTH OF A WEAK BAROCLINIC
ZONE COULD BRING BETTER CHANCES OF POPCORN SHOWERS/ISOLATED STORMS
ACROSS CROOK/WESTON/BLACK HILLS/SW SD COUNTIES SUNDAY AFTERNOON.
SEVERE WEATHER IS NOT EXPECTED. BY THE TIME THE PRECIPITATION TAPERS
OFF SUNDAY NIGHT, NW SD THROUGH CENTRAL SD COULD SEE OVER AN INCH OF
QPF...POSSIBLY MORE THAN 1.5" IN SOME LOCATIONS.
DISCUSSION
(THIS AFTERNOON THROUGH FRIDAY)
ISSUED AT 1106 AM MDT SAT JUN 20 2026
CURRENT UPPER-AIR ANALYSIS AND WATER VAPOR IMAGERY DEPICT WEAK
TROUGHING OVER THE GREAT LAKES REGION WITH A SHORTWAVE POSITIONED
OVER SOUTHERN ID/WESTERN WY AND AN UPPER LOW OVER SOUTHERN AB.
SATELLITE IMAGERY INDICATES INCREASED WV AND CLOUD COVER OVER WY AND
THE NE PANHANDLE. RADAR RETURNS SHOW THAT SOME EARLY THUNDERSTORMS
HAVE FORMED OVER SOUTH-CENTRAL SD AND CENTRAL NE, WITH SOME LIGHT
SHOWERS OVER EAST-CENTRAL WY. SURFACE OBSERVATIONS SHOW TEMPERATURES
MAINLY IN THE 60S TO LOW 70S, WITH DEW POINTS IN THE 40S ACROSS
NORTHEAST WY AND 40S TO LOW 50S ACROSS WESTERN SD. WINDS ARE
GENERALLY SOUTHEASTERLY AT 10 TO 20KTS GUSTING TO 30KTS ACROSS
NORTHEAST WY AND WESTERN SD. GUSTY SOUTHEASTERLY WINDS UP TO 40KTS
WILL CONTINUE TO DEVELOP OVER THE SD PLAINS, WITH THE STRONGEST
WINDS OVER NORTHWEST SD.
CONFIDENCE IN SEVERE WEATHER TODAY IS CURRENTLY MIXED DUE TO
INCREASED CLOUD COVER OVER MUCH OF NORTHEASTERN WY AND WESTERN SD AS
THE SHORTWAVE APPROACHES. THE 12Z HREF RUN STILL SUGGESTS CONDITIONS
WILL STILL BE LEANING TOWARDS A MODERATE CHANCE FOR SEVERE STORMS
OVER NORTHEAST WY, THE BLACK HILLS, AND INTO FAR SOUTHWESTERN SD.
SPC HAS MOVED THE SLIGHT RISK OUT OF THE REGION, LEAVING JUST THE
MARGINAL RISK FOR NORTHEAST WY AND SOUTHWESTERN SD. THERE IS A 2%
TORNADO RISK AND 5% SEVERE WIND AND HAIL RISK FOR THOSE AREAS. A
POSSIBLE LANDSPOUT CAN'T BE RULED OUT OVER NORTHEAST WY. STORMS
WILL CONTINUE TO DEVELOP LATE THIS MORNING/EARLY AFTERNOON ACROSS
NORTHEAST WY AND SOUTH-CENTRAL SD. MULTIPLE ROUNDS OF STORMS ARE
EXPECTED TO MOVE THROUGH NORTHEAST WY INTO WESTERN SD THROUGHOUT
THE AFTERNOON AND EVENING. THE FIRST ROUND OF STORMS MAY WIPE OUT
THE ENVIRONMENT, RESULTING IN WEAKER STORMS DURING THE SECOND
ROUND. WE WILL HAVE TO WAIT AND SEE IF THE ENVIRONMENT WILL BE
ABLE TO RECOVER. THE BEST CHANCE FOR SEVERE WEATHER WILL STILL BE
SOUTHEAST WY INTO THE NE PANHANDLE WHERE CONDITIONS ARE MORE
FAVORABLE.
THUNDERSTORMS AND SHOWERS WILL CONTINUE TO MOVE THROUGH THE REGION
INTO THE OVERNIGHT HOURS AND PERSIST INTO SUNDAY AS THE SHORTWAVE
CONTINUES TO MOVE ACROSS THE REGION. SEVERE WEATHER IS UNLIKELY. QPF
VALUES THROUGH SUNDAY EVENING ARE STILL TRENDING TOWARDS AT LEAST
0.50" FOR MOST LOCATIONS, WITH HIGHER AMOUNTS EAST OF THE BLACK
HILLS, WHERE 1.00" TO 1.50" IS NOT OUT OF THE QUESTION. TEMPERATURES
WILL BE COOLER SUNDAY WITH HIGHS RANGING IN THE 60S TO LOW 70S.
WINDS WILL ALSO BE ON THE LIGHTER SIDE.
NEXT WEEK WILL START OFF COOLER AND WET AS A COLD FRONT PUSHES
THROUGH, BRINGING ANOTHER ROUND OF SHOWERS TO THE REGION. CHANCES
FOR PRECIPITATION WILL CONTINUE THROUGHOUT THE WEEK AS TEMPERATURES
GRADUALLY WARM UP BY THE END OF THE WEEK.
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 506 AM MDT SUN JUN 21 2026
WIDESPREAD MVFR-IFR (LOCAL LIFR) CONDS EXPECTED OVER MUSH OF
WESTERN SD TODAY, WITH SCT SHRA AND ISOLD TS. CONDS MAY IMPROVE A
BIT THIS AFTERNOON BEFORE THEY DETERIORATE THIS EVENING WITH
EASTERLY UPSLOPE FLOW DEVELOPING. MAINLY VFR CONDS EXPECTED
ACROSS NORTHEAST WY TODAY. AS RETURN FLOW DEVELOPS TONIGHT, MVFR-
IFR STRATUS WILL BE POSSIBLE LATE.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
UPDATE...13
DISCUSSION...SCHULTZ
AVIATION...JC
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