875
FXUS63 KFSD 210452
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1152 PM CDT WED MAY 20 2026
KEY MESSAGES
- PERIODS OF LIGHT TO MODERATE SHOWERS WILL RETURN BY FRIDAY
BRINGING BENEFICIAL RAINFALL TO THE AREA. WHILE EXACT AMOUNTS
ARE UNCERTAIN, THERE IS GROWING CONFIDENCE IN HALF AN INCH OR
GREATER FOR MOST AREAS.
- BELOW NORMAL TEMPERATURES WILL CONTINUE THROUGH SATURDAY
BEFORE WARMER CONDITIONS RETURN FROM SUNDAY ONWARDS.
UPDATE
ISSUED AT 855 PM CDT WED MAY 20 2026
THE FORECAST REMAINS ON TRACK WITH ANY LINGERING SPRINKLES TO VERY
LIGHT SHOWERS BEING THWARTED BY A DRY SUB-CLOUD LAYER ACCORDING TO
SOUNDINGS. BESIDES THE LINGERING CLOUD COVER, TONIGHT SHOULD BE
MOSTLY QUIET AS TEMPERATURES APPROACH THE LOW 40S FOR THE NIGHT.
LOOKING INTO THURSDAY, STILL LOOKING QUIET FOR MOST OF THE DAY AS
TEMPERATURES REACH THE LOW TO UPPER 60S. WE'LL START TO SEE AN
INCREASE IN CLOUD COVER OVERNIGHT FROM SOUTH TO NORTH AS WARM AIR
ADVECTION (WAA) STRENGTHENS AHEAD OF OUR NEXT WAVE/RAIN CHANCES.
OVERALL, NO SIGNIFICANT CHANGES IN THE FORECAST HAVE BEEN NOTED
BESIDES THE NBM CATCHING UP ON THE QPF SIDE OF THINGS. WITH THIS IN
MIND, MANY AREAS ARE STILL ON TRACK TO RECEIVE UPWARDS OF 0.50" TO
0.75" OF AN INCH OF RAIN DURING THE DAY ON FRIDAY WITH THE POTENTIAL
FOR ISOLATED POCKETS OF UP TO 1.00+" WEST OF I-29. LASTLY, MAKE SURE
TO PLAN FOR THE WET AND DREARY CONDITIONS AS MOST OF THIS ACTIVITY
WON'T BE OUT OF OUR AREAS UNTIL LATE EVENING.
DISCUSSION
ISSUED AT 1257 PM CDT WED MAY 20 2026
A WEAK WAVE AND MID LEVEL MOISTURE AROUND THE DGZ MOVES IN TONIGHT,
BRINGING A SMALL THREAT FOR SHOWERS. MOST LOCATIONS WILL SEE A
FAIRLY STOUT DRY LAYER BELOW THE INCOMING MOISTURE WHICH WILL
SEVERELY LIMIT RAINFALL POTENTIAL. ONE EXCEPTION MAY BE WEST OF THE
JAMES RIVER LATE THIS AFTERNOON AND EARLY THIS EVENING WHEN A LITTLE
WEAK INSTABILITY DEVELOPS DURING PEAK HEATING WHICH COULD SUPPORT
ISOLATED SHOWERS THERE.
LIFT AND VERY WEAK INSTABILITY MOVES IN ON THURSDAY AHEAD OF THE
NEXT WAVE. THE CHANCES FOR RAINFALL REMAINS VERY LIMITED WITH THIS.
OTHERWISE EXPECTING PARTLY TO MOSTLY CLOUDY SKIES AND HIGHS IN THE
60S.
THURSDAY NIGHT INTO FRIDAY WILL SEE WARM ADVECTION AND UPPER LEVEL
SUPPORT SPREAD INTO THE AREA. MOST OF THURSDAY NIGHT WILL SEE THE
BETTER CHANCES REMAIN TO THE SOUTH OF THE MISSOURI RIVER, BUT AFTER
MIDNIGHT CHANCES WILL INCREASE. FOR THE MOST PART, SHOWERY AND VERY
ISOLATED THUNDERSTORMS WILL BE INSTABILITY DRIVEN NEAR AND EAST OF I-
29, WHILE WEST OF I-29 BETTER UPPER LEVEL SUPPORT FOR RAINFALL WILL
BE THE DRIVING FACTOR. WHILE THE CONVECTIVE PORTION IS OF COURSE A
LITTLE LESS PREDICTABLE, ASSUMING SOME CONVECTIVE COMPONENT DOES
DEVELOP A FEW LOCATIONS COULD SEE 1-2" OF RAIN. MANY OF THE LATEST
MODELS ARE EACH INDICATING SWATHS ABOUT 20-40 MILES WIDE OF 1-2"
AMOUNTS. WHAT ALSO APPEARS TO BE FAIRLY CONSISTENT IS THAT
ESPECIALLY WEST OF HIGHWAY 81 IS WHERE THE MOST CONSISTENT
SUGGESTIONS FOR A MORE WIDESPREAD QUARTER TO THREE QUARTERS OF AN
INCH OF RAIN IS POSSIBLE.
MOST OF THE LIFT WILL DRIFT NORTHEAST ON SATURDAY WITH A FEW SPRINKLES
POSSIBLE IN THE MORNING. OTHERWISE A MILD DAY WITH HIGHS MOST IN THE
60S TO LOWER 70S.
MODEL SOUNDINGS HINTING AT SOME WEAK, SURFACE BASED INSTABILITY ON
SUNDAY AFTERNOON AND EVENING WHICH MAY ALLOW FOR AN ISOLATED
THUNDERSTORM TO DEVELOP. WITH SOME DRY LOW LEVELS AND WEAK SHEAR
GUSTY WINDS WOULD LIKELY BE THE MAIN THREAT IF ANYTHING CAN DEVELOP.
CONFIDENCE IN THIS IS LOW FOR NOW.
BY MONDAY STRONGER SOUTHERLY FLOW SETS UP AN CONTINUES THROUGH THE
MIDDLE OF THE WEEK. HIGH TEMPERATURES IN THE 80S SHOULD BE COMMON.
WITH UPPER LEVEL RIDGING IN PLACE MONDAY THROUGH WEDNESDAY AND VERY
LITTLE UPPER LEVEL ENERGY EXPECTED TO MOVE THROUGH THE AREA MOSTLY
DRY CONDITIONS ARE EXPECTED. SOME HINTS OF SOME SUPPORT WEDNESDAY
INTO THURSDAY SO WILL HAVE TO SEE IF THIS COMES TO FRUITION.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 1142 PM CDT WED MAY 20 2026
VFR CONDITIONS WILL CONTINUE THIS TAF PERIOD. BESIDES A FEW
LINGERING SHOWERS IN A MID-LEVEL DECK TONIGHT, SHOULD SEE
MOSTLY QUIET CONDITIONS PERSIST THROUGH FRIDAY AFTERNOON.
OTHERWISE, SOUTHEASTERLY WINDS WILL GRADUALLY INCREASE WITH
GUSTS BETWEEN 20-30 MPH EXPECTED THROUGH EARLY EVENING. LASTLY,
SCATTERED SHOWERS WILL RETURN TO THE AREAS SOUTH OF I-90 TOWARDS
THE END OF THE TAF PERIOD. AS A RESULT, ADDED A PROB30 GROUP
INTO KSUX FROM 04Z-06Z.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...05
DISCUSSION...08
AVIATION...05
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