541
FXUS63 KFSD 220533
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1233 AM CDT SAT AUG 22 2026
KEY MESSAGES
- LOW CHANCES (LESS THAN 20%) FOR SHOWERS AND STORMS THROUGH
SUNRISE SOUTH OF THE MISSOURI RIVER. SEVERE WEATHER RISK IS
NOT EXPECTED.
- SLIGHTLY COOLER WEATHER FOR THE WEEKEND. SATURDAY SHOULD
REMAIN DRY WITH RAIN CHANCES (40-70%) RETURNING TO PORTIONS
OF THE AREA BY SUNDAY MORNING. RAINFALL AMOUNTS COULD EXCEED A
TENTH OF AN INCH.
- ADDITIONAL CHANCES FOR RAIN, AND POTENTIALLY STRONG TO SEVERE
THUNDERSTORMS (5-15%), ARE POSSIBLE THROUGH NEXT WEEK.
DETAILS ARE UNCERTAIN, SO CONTINUE TO CHECK THE LATEST
FORECAST FOR THE MOST UP TO DATE INFORMATION.
UPDATE
ISSUED AT 831 PM CDT FRI AUG 21 2026
NO MAJOR CHANGES TO THE FORECAST FOR TONIGHT AND TOMORROW. A
WEAK BOUNDARY HEADING TOWARDS I-90 HAS SET OFF A FEW SHOWERS AND
STORMS AS IT MOVES SOUTHWARD, MAINLY OVER SOUTHWEST MINNESOTA
AND FAR EASTERN SOUTH DAKOTA. SHOULD SEE THIS CONTINUE
WEAKENING WITH SOUTHEASTWARD EXTENT AS WE LOSE DAYTIME HEATING.
MEAGER INSTABILITY IS IN PLACE, SO JUST EXPECTING WEAK
THUNDERSTORMS WITH BRIEF DOWNPOURS AND SOME LIGHTNING OVER
ROUGHLY THE NEXT HOUR.
HIGHER INSTABILITY VALUES (2,000+ J/KG OF MUCAPE) ARE LOCATED
NEAR AND SOUTH OF THE MISSOURI RIVER, BUT THIS WILL SLOWLY SAG
SOUTHWARD THROUGH TONIGHT, THOUGH SOME GUIDANCE KEEPS AROUND 1,000-
1,500 J/KG IN PLACE OVER GREGORY COUNTY THROUGH THE EARLY MORNING
HOURS. WITH THE BETTER LIFT TO THE SOUTH OF THE AREA, THUNDERSTORMS
ARE UNLIKELY. IF A STORM WERE CLIP OUR AREA, SEVERE WEATHER IS
UNLIKELY AS SKINNY CAPE PROFILES WOULD REALLY HINDER THE DEVELOPMENT
OF ANY LARGE HAILSTONES AND THE ELEVATED NATURE OF ANY STORM WOULD
PRECLUDE A DAMAGING WIND THREAT. ANY STORMS WILL BE WELL SOUTH OF
THE AREA BY SUNRISE SATURDAY, LEADING TO A WARM AND PLEASANT
LATE SUMMER DAY!
DISCUSSION
ISSUED AT 139 PM CDT FRI AUG 21 2026
QUIET CONDITIONS PERSIST THIS AFTERNOON AS TEMPERATURES HAVE WARMED
TO THE 70S AND 80S ACROSS THE AREA. QUIET CONDITIONS ARE EXPECTED TO
CONTINUE FOR THE REST OF THE DAY AS THE COLD FRONT HAS FULLY PUSHED
THROUGH THE AREA. THIS WILL KEEP STORM CHANCES SOUTH AND WEST OF THE
FORECAST AREA. CAN'T RULE OUT THE LOW POSSIBILITY (LESS THAN 20%) OF
A SHOWER OR WEAK STORM PASSING ALONG AND SOUTH OF THE MISSOURI RIVER
THIS AFTERNOON, EVENING, AND POTENTIALLY INTO THE OVERNIGHT HOURS.
SHOULD THIS OCCUR, THE CHANCE FOR A SEVERE STORM IS LOW. SURFACE
RIDGING WILL BEGIN TO SLIDE INTO THE FORECAST AREA TONIGHT,
RESULTING IN LIGHT AND VARIABLE WINDS WITH LOWS FALLING TO THE UPPER
50S TO LOW 60S. PATCHY FOG IS AGAIN ON THE TABLE BUT WITH DRIER AIR
IN PLACE, THINK THAT ANY FOG THAT DOES DEVELOP WILL ONCE AGAIN BE
TIED TO A FEW RIVER VALLEY'S.
SATURDAY BEGINS THE WEEKEND ON THE QUIET SIDE AS HIGH PRESSURE
PUSHES THROUGH THE NORTHERN PLAINS. HIGH TEMPERATURES WILL BE A BIT
COOLER IN THE UPPER 70S TO LOW TO MID 80S, WITH A CONTINUATION OF
LIGHT NORTHERLY WINDS. THIS WILL MAKE FOR A WONDERFUL SATURDAY,
PERFECT FOR OUTDOOR ACTIVITIES! RAIN CHANCES WILL INCREASE LATE
SATURDAY NIGHT THROUGH SUNDAY AS A WEAK SHORTWAVE TROUGH ROUNDS THE
TOP OF A BUILDING UPPER LEVEL RIDGE. THIS WILL RESULT IN INCREASING
CHANCES FOR RAIN ACROSS THE AREA FOR THE DAY ON SUNDAY. CLOUD COVER
WITH THE ASSOCIATED CHANCES FOR RAIN WILL KEEP HIGH TEMPERATURES A
BIT COOLER IN THE UPPER 70S TO LOW 80S. WHILE SOME SHOWERS ARE
POSSIBLE DURING THE MORNING TIMEFRAME, THE HIGHEST CHANCES FOR RAIN
WILL COME SUNDAY EVENING AND NIGHT AS THE MAIN SHORTWAVE PUSHES
THROUGH THE AREA. THE ENSEMBLES SHOW A BROAD 40-70% CHANCE FOR
RAINFALL TOTALS TO EXCEED A TENTH OF AN INCH. SOUNDINGS SHOW SOME
ELEVATED INSTABILITY IN PLACE SO THUNDERSTORMS ARE POSSIBLE, THOUGH
SEVERE STORMS ARE NOT EXPECTED AT THIS TIME DUE TO WEAK SHEAR
PROFILES. WITH NON-SEVERE STORMS ON THE TABLE, RAINFALL AMOUNTS
COULD BE LOCALLY HIGHER DEPENDING ON HOW STORMS TRACK.
AN ACTIVE PATTERN CONTINUES ALOFT FOR NEXT WEEK. MEDIUM RANGE
GUIDANCE SHOWS SHORTWAVE TROUGHS CONTINUING TO PUSH THROUGH THE
NORTHERN PLAINS WITHIN THE NORTHWEST FLOW REGIME. THIS WILL LEAD TO
CHANCES FOR RAIN ALMOST EVERY DAY NEXT WEEK. HOWEVER, THE ENSEMBLES
SHOW A LARGE VARIANCE IN RAINFALL PROBABILITIES DUE TO THE
DIFFERENCES IN THESE UPPER LEVEL FEATURES. LATEST MACHINE LEARNING
(ML) GUIDANCE DOES SHOW LOW PROBABILITIES (5-15%) FOR SEVERE WEATHER
THROUGHOUT THE WEEK. DETAILS FOR SEVERE WEATHER REMAINS UNCERTAIN SO
CONTINUE TO CHECK THE FORECAST FOR THE MOST UP TO DATE INFORMATION.
ASIDE FROM RAIN AND STORM CHANCES, HIGH TEMPERATURES LOOK TO REMAIN
IN THE UPPER 70S AND 80S.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 1229 AM CDT SAT AUG 22 2026
PATCHY LIGHT FOG IS POSSIBLE TONIGHT MAINLY IN RIVER VALLEYS
AND OTHER LOW LYING AREAS, THOUGH WIDESPREAD ISSUES ARE NOT
EXPECTED. THE ONLY TAF SITE THAT APPEARS TO AT LEAST HAVE A
CHANCE OF LIGHT FOG IS KHON, BUT EVEN THEN WE'RE LOOKING AT A
LESS THAN 15% CHANCE OF DEVELOPMENT THERE.
QUIET CONDITIONS ARE EXPECTED THROUGH THE PERIOD OUTSIDE OF A
ROGUE THUNDERSTORM SOUTH OF THE MISSOURI RIVER THROUGH SUNRISE
TODAY. LIGHT AND VARIABLE WINDS ARE EXPECTED THROUGH DAYBREAK.
THEN WINDS WILL BE MAINLY OUT OF THE NORTH-NORTHEAST AROUND
5-10 KTS THROUGH THE DAY TODAY, BUT WILL START TURNING MORE
EASTERLY INTO THE LATER EVENING HOURS.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...SAMET
DISCUSSION...MEYERS
AVIATION...SAMET
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