144
FXUS63 KFSD 210539
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1239 AM CDT SUN JUN 21 2026
KEY MESSAGES
- SCATTERED SHOWERS WITH ISOLATED THUNDERSTORMS CONTINUE TONIGHT
MAINLY ALONG THE MISSOURI RIVER. STORMS ARE EXPECTED TO
GRADUALLY BECOME MORE WIDESPREAD OVERNIGHT. WHILE SEVERE
WEATHER IS NOT EXPECTED, LIGHTNING IS POSSIBLE.
- POCKETS OF MODERATE TO HEAVY RAINFALL ARE EXPECTED AT TIMES
OVERNIGHT AND THROUGH THE FIRST HALF OF SUNDAY. FLOODING IS
NOT A CONCERN AT THIS TIME, BUT LOCALIZED PONDING IS
POSSIBLE.
- BENEFICIAL ACCUMULATIONS OF 0.50" TO 1.00" ARE EXPECTED ALONG
THE MISSOURI RIVER VALLEY WITH ISOLATED POCKETS OF HIGHER
POSSIBLE ACROSS SOUTHCENTRAL SD. FLASH FLOODING IS NOT
EXPECTED.
- BELOW NORMAL TEMPERATURES AND PERIODIC RAIN CHANCES CONTINUE
INTO THE START OF NEXT WEEK. SEVERE WEATHER CHANCES REMAIN LOW.
UPDATE
ISSUED AT 909 PM CDT SAT JUN 20 2026
AN AREA OF ELEVATED SHOWERS AND THUNDERSTORMS IS ONGOING FROM
CENTRAL SOUTH DAKOTA SOUTHEAST ALONG THE MISSOURI RIVER VALLEY AND
INTO EASTERN NEBRASKA AND WESTERN IOWA. THESE ARE EXPECTED TO EXPAND
NORTHWARD WITH TIME, POSSIBLY AS FAR AS I-90. AN AREA OF LOW TO MID-
LEVEL CONVERGENCE, WAA, AND AN INCREASING LLJ SUPPORTED BY A MID-
LEVEL PASSING SHORTWAVE WILL KEEP SHOWERS AND THUNDERSTORMS IN THE
FORECAST THROUGH THE OVERNIGHT. A SECOND STRONGER MID TO UPPER-LEVEL
WAVE WILL PUSH INTO THE REGION FROM THE NORTHWEST EARLY SUNDAY
MORNING. AS IT DOES SO IT WILL PUSH THIS FIRST SYSTEM OUT AND THERE
WILL BE A BRIEF BREAK IN SHOWERS EARLY MORNING THROUGH ABOUT MID-
MORNING. BY LATE MORNING SIMILAR ATMOSPHERIC CONDITIONS AS TONIGHT
WORK WITH INCREASED FORCING AS THE MID TO UPPER WAVE PASSES THROUGH.
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL RESULT, THIS TIME
MOSTLY ALONG AND NORTH OF I-90. WEAK ELEVATED INSTABILITY WILL
SUPPORT A FEW LIGHTNING STRIKES BUT SEVERE WEATHER IS NOT
ANTICIPATED. SOME ISOLATED POCKETS OF HEAVY RAIN ARE POSSIBLE, BUT
RISKS FOR FLOODING REMAIN LOW. STORMS DISSIPATE THROUGH THE
AFTERNOON. IN TOTAL, BENEFICIAL RAINFALL IS EXPECTED ACROSS
MUCH OF THE REGION. UP TO AN INCH FROM CENTRAL SOUTH DAKOTA
ALONG THE MISSOURI RIVER COUNTIES. A HALF TO 3/4 OF AN INCH FOR
MOST OF THE JAMES RIVER VALLEY, AND A TENTH TO A QUARTER OF AN
INCH ELSEWHERE. SOUTHWEST MINNESOTA WILL BE THE AREA SEEING THE
LOWERS RAINFALL.
HIGHS FOR SUNDAY WILL BE COOL, IN THE MID 60S TO LOW 70S. ANOTHER
ROUND OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE MONDAY NIGHT
INTO TUESDAY MORNING. DETAILS ARE UNCERTAIN AT THIS TIME, BUT A FEW
STRONGER STORMS COULD BE POSSIBLE.
DISCUSSION
ISSUED AT 202 PM CDT SAT JUN 20 2026
CURRENTS & TONIGHT: ANOTHER SEASONABLE DAY CONTINUES! TAKING A LOOK
ACROSS THE AREA, MOSTLY CLEAR CONDITIONS PERSIST THIS AFTERNOON WITH
MOST AREAS SITTING IN THE MID TO UPPER 70S AND LOW 80S. THIS ALONG
WITH LIGHTER SURFACE WINDS HAS MADE FOR BEAUTIFUL CONDITIONS WEATHER-
WISE. UNFORTUNATELY, THESE CONDITIONS WILL BE SHORT-LIVED AS CLOUD
COVER BUILDS IN FROM SOUTHWEST TO NORTHEAST INTO THE EVENING AS OUR
NEXT SYSTEM APPROACHES. FROM HERE, INCREASING DPVA/FRONTAL FORCING
ALONG WITH A WEAK LLJ (20-35KTS) WILL LIKELY LEAD TO THE DEVELOPMENT
OF SCATTERED SHOWERS WITH ISOLATED THUNDERSTORMS ALONG THE MISSOURI
RIVER VALLEY AND PORTIONS OF SOUTHCENTRAL SD INITIALLY. EXPECT
COVERAGE TO BECOME MORE WIDESPREAD OVERNIGHT AS THE PREVIOUSLY
MENTIONED SHORTWAVE ZIPS EASTWARDS ACROSS NE JUST SOUTH OF THE SD/NE
BOARDER LEADING TO A BLOSSOMING OF DEVELOPMENT.
WHILE SEVERE WEATHER IS NOT EXPECTED; THE INCREASING LIFT AND SHEAR
WILL LEAD TO POCKETS OF MODERATE TO HEAVY RAINFALL AT TIMES FROM
LATE THIS EVENING THROUGH SUNDAY MORNING. NONETHELESS, ANY RAIN FOR
THE PREVIOUSLY MENTIONED AREAS WILL BE WELCOMED ESPECIALLY SINCE
THIS IS WHERE THE WORST CONDITIONS OF OUR D2-D3 DROUGHT ARE SET UP
ACCORDING TO THE DROUGHT MONITOR. TAKING A CLOSER LOOK, DON'T THINK
ANY OF THIS DEVELOPING ACTIVITY WILL TOUCH THE 2-3" IN/HR RATES
NECESSARY FOR FLASH FLOODING SO WE SHOULD BE IN GOOD SHAPE OVERALL.
OTHERWISE, EXPECT THE SCATTERED RAIN CHANCES TO CONTINUE THROUGH AT
LEAST SUNDAY MORNING BEFORE ADDITIONAL RAIN CHANCES MOVE IN FROM
CENTRAL SD WITH OUR NEXT SYSTEM. LASTLY, EXPECT ANOTHER MILD NIGHT
WITH LOWS EXPECTED TO GRADUALLY DECREASE INTO THE MID TO UPPER 50S.
SUNDAY-TUESDAY: LOOKING INTO SUNDAY, THE DREARIER CONDITIONS WILL
PERSIST THROUGHOUT THE DAY AS ADDITIONAL RAIN CHANCES (40%-80%)
DEVELOP WITH THE AN APPROACHING MID-LEVEL LOW. WHILE SEVERE WEATHER
IS NOT EXPECTED, AMPLE MOISTURE AND STRENGTHENING DPVA/FRONTAL
FORCING SHOULD DO JUST ENOUGH TO KEEP THE SCATTERED SHOWERS GOING
DURING THE DAY WITH A FEW ADDITIONAL POCKETS OF MODERATE RAINFALL.
NONETHELESS, SHOULD SEE MUCH OF THE SHOWER ACTIVITY BEGIN TO TAPER
OFF DURING THE EVENING WITH THE LOSS OF DIURNAL HEATING AND AS THE
PREVIOUSLY MENTIONED SYSTEM TRACKS INTO THE NORTHCENTRAL NE.
OTHERWISE, QUIETER CONDITIONS SHOULD RETURN BY MONDAY AS ZONAL FLOW
RETURNS ALOFT. OUR NEXT CHANCE FOR PRECIPITATION WILL LIKELY COME BY
TUESDAY AS A COLD FRONT PROGRESSES THROUGH THE AREA. WHILE THE
BETTER FORCING WILL LIKELY BE TO OUR NORTH ACROSS NORTHEASTERN SD,
WE COULD GET JUST ENOUGH INSTABILITY/SHEAR TO GET A CONDITIONAL RISK
FOR STRONGER STORMS DURING THE AFTERNOON TO EVENING HOURS. HOWEVER,
THERE IS STILL SOME UNCERTAINTY. EITHER WAY, THIS WOULD BE THE NEXT
PERIOD TO WATCH FOR ANY ORGANIZED CONVECTION. LASTLY, NEAR TO BELOW
NORMAL TEMPERATURES WILL CONTINUE ACROSS THE AREA THROUGH TUESDAY
WITH HIGHS MAINLY IN THE LOW TO UPPER 70S.
WEDNESDAY ONWARDS: HEADING INTO THE MIDWEEK, QUIETER CONDITIONS
SHOULD RETURN FOR WEDNESDAY AND THURSDAY AS A SURFACE HIGH TRACKS
THROUGH OUR AREA. FROM HERE, THE WAVE TRAIN RETURNS BY FRIDAY AS
QUASI-ZONAL FLOW HELPS USHER IN MULTIPLE SHORTWAVES INCREASING
THE CHANCES FROM SHOWERS AND POTENTIALLY THUNDERSTORMS ALMOST
DAILY (EVERY 24-36 HOURS) INTO THE FOLLOWING WEEK. WHILE THE
CHANCES FOR SEVERE WEATHER ARE STILL UNCERTAIN AT THIS TIME,
THIS IS ANOTHER PERIOD THAT WILL NEED TO BE MONITORED CLOSELY
MOVING FORWARD. LASTLY, WE'LL CONTINUE TO SEE TEMPERATURES BUILD
TOWARDS MORE SEASONAL CONDITIONS WITH HIGHS INCREASING FROM THE
LOW TO MID 70S ON WEDNESDAY TO THE LOW TO MID 80S BY SATURDAY.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1235 AM CDT SUN JUN 21 2026
VFR CONDITIONS ARE BEGINNING TO DEGRADE AS CLOUDS LOWER AND SHOWERS
BECOME MORE NUMEROUS ACROSS THE REGION. EXPECT OVERNIGHT CEILINGS
AND VISIBILITY TO HOVER BETWEEN VFR AND MVFR AND PERIODICALLY IFR
UNDER HEAVIER STORMS. SEVERE WEATHER IS NOT ANTICIPATED, BUT SOME
LIGHTNING IS POSSIBLE. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
CONTINUE OVERNIGHT AND INTO THE DAY SUNDAY. STORMS GRADUALLY
TAPER OFF SUNDAY LATE AFTERNOON.
WINDS ARE LIGHT AND EASTERLY WITH SOME SLIGHT VARIABILITY. AFTER
SUNRISE WINDS WILL BECOME EAST AND INCREASE WITH GUSTS OF 15-25 KTS
EXPECTED BY AFTERNOON. WINDS DECREASE AFTER SUNSET BECOMING LIGHT
AND VARIABLE NEAR THE END OF THE PERIOD.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...AJP
DISCUSSION...05
AVIATION...AJP
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