307
FXUS63 KFSD 222328
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
628 PM CDT SAT AUG 22 2026
KEY MESSAGES
- THE NEXT BETTER CHANCE FOR SHOWERS AND STORMS IS SUNDAY NIGHT
(50-70%). LOCALLY HEAVY RAIN AND ISOLATED SEVERE STORMS ARE
POSSIBLE.
- OTHERWISE MOST DAYS THROUGH NEXT WEEK WILL SEE HIGHS IN THE
80S AND LOWS IN THE UPPER 50S TO LOWER 60S.
DISCUSSION
ISSUED AT 142 PM CDT SAT AUG 22 2026
A QUIET NIGHT IS AHEAD AS HIGH PRESSURE DRIFTS EAST. SOUTHERLY FLOW
WILL DEVELOP IN CENTRAL SD LATER TONIGHT AND BECOME MORE
ESTABLISHED ACROSS THE AREA THROUGH SUNDAY. THE LIGHT WINDS WILL
ALLOW TEMPERATURES TO FALL INTO THE LOWER 50S, ESPECIALLY EAST OF I-
29.
THE UPPER LEVEL WAVE RESPONSIBLE FOR THE LOW LEVEL WINDS TURNING
SOUTHERLY WILL MOVE INTO CENTRAL SD TOMORROW MORNING, AND EASTWARD
AND SOUTHEAST FROM THERE THROUGH THE DAY. WITH FAIRLY STOUT LOW TO
MID LEVEL DRY AIR, MAINLY AN INCREASE IN CLOUD COVER IS EXPECTED
THROUGH THE MORNING. THE EXCEPTION WILL BE SOUTH CENTRAL SD WHERE
ENOUGH MOISTURE MAY ALLOW FOR 500-1000 J/KG OF ELEVATED CAPE, WHICH
WILL SUPPORT SOME SPOTTY SHOWERS AND THUNDERSTORMS. SEVERE WEATHER
IS NOT EXPECTED.
LIFT WILL GRADUALLY INCREASE THROUGH THE DAY INTO SUNDAY NIGHT,
WHEN A MODERATELY STRONGER LLJ FOCUSES ON THE AREA. GIVEN FAIRLY
WEAK SHEAR AND CAPE VALUES GENERALLY UNDER 1000 J/KG, SEVERE WEATHER
LOOKS UNLIKELY. HOWEVER WITH A FREEZING LEVEL AROUND 13 KFT, LOCALLY
HEAVY RAIN WILL BE POSSIBLE. NOT MUCH AGREEMENT ON THE LOCATION OF
THE HEAVIER RAIN WITH THE MODELS PRETTY INCONSISTENTLY PLACING THE
MID LEVEL WAVE ACROSS THE AREA. SOME HINTS THAT THE LLJ WILL FOCUS
SOMEWHERE ON THE SD SIDE, BUT CONFIDENCE IS LOW.
THIS WAVE MOVES OUT OF THE AREA ON MONDAY BUT ANOTHER WEAKER WAVE
MOVES BY TO THE NORTH ON MONDAY NIGHT AND BRINGS A SMALL INCREASE IN
WARM AIR ADVECTION, WHICH COULD SPARK A FEW SHOWERS AND
THUNDERSTORMS.
MAINLY NORTHWEST FLOW ALOFT CONTINUES TUESDAY INTO NEXT WEEKEND. THIS
WILL BRING PERIODIC SMALL CHANCES FOR SHOWERS AND THUNDERSTORMS
THROUGHOUT THE WEEK WITH LITTLE AGREEMENT ON EXACTLY WHEN. OTHERWISE
LOWS SHOULD MAINLY BE FROM THE MID 50S TO MID 60S WITH HIGHS IN THE
80S.
AVIATION /00Z TAFS THROUGH 00Z MONDAY/
ISSUED AT 626 PM CDT SAT AUG 22 2026
VERY PATCHY FOG IS POSSIBLE LATE TONIGHT INTO SUNDAY MORNING,
MAINLY IN RIVER VALLEYS AND OTHER LOW-LYING AREAS. SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS WILL MOVE INTO SOUTH-CENTRAL
SOUTH DAKOTA LATE TONIGHT AND DRIFT SOUTHEASTWARD THROUGH THE
DAY ON SUNDAY.
WINDS WILL TURN LIGHT AND VARIABLE NEAR AND EAST OF I-29 HEADING
INTO TONIGHT. MEANWHILE, AREAS WEST OF I-29 WILL SEE WINDS PICK UP A
BIT OUT OF THE EAST AND THEN SOUTHEAST HEADING TOWARDS DAYBREAK
SUNDAY. WINDS WILL PICK UP ACROSS MOST OF THE AREA THROUGH THE DAY
SUNDAY OUT OF THE SOUTH. WINDS WILL GET PRETTY BREEZY WEST OF THE
JAMES RIVER SUNDAY AFTERNOON, WHERE GUSTS OF 25-30 KTS ARE EXPECTED.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...08
AVIATION...SAMET
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