354
FXUS63 KFSD 261128
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
628 AM CDT FRI JUN 26 2026
KEY MESSAGES
- NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES PREVAIL THROUGH
SATURDAY. A COUPLE SPOTTY SHOWER AND STORM CHANCES ARE
POSSIBLE DURING THIS TIME.
- AN EXTENDED PERIOD OF HEAT AND HUMIDITY IS EXPECTED STARTING
SUNDAY INTO NEXT WEEK. HEAT INDICES UP TO THE LOW 100S COULD
LEAD TO MAJOR TO EXTREME HEAT RISK. BEGIN PLANNING NOW TO
REDUCE RISK OF HEAT ILLNESS AND IMPACTS.
- AN ACTIVE PATTERN ALOFT LEADS TO ISOLATED CHANCES FOR STRONGER
STORMS SATURDAY NIGHT AND AGAIN INTO EARLY AND MID NEXT WEEK.
HOWEVER, SOME UNCERTAINTY REMAINS.
UPDATE
ISSUED AT 344 AM CDT FRI JUN 26 2026
INCREASED POPS A BIT FOR THE EARLY MORNING HOURS, ALTHOUGH
PRECIPITATION CONTINUES TO STRUGGLE NORTH OF I-90 WITH DRY SUB CLOUD
LAYER. ANY LINGERING SHOWERS/SPRINKLES COME TO AN END THROUGH LATE
MORNING. THUNDER RISK REMAINS LOW. HIGHS TODAY WARM INTO THE UPPER
70S TO LOWER 80S WITH DECREASING AFTERNOON CLOUDS. WIND GUSTS AROUND
30 MPH THIS AFTERNOON FOR SOUTH CENTRAL SD.
SLIGHTLY WARMER BUT MORE HUMID AND BREEZY ON SATURDAY, WITH GUIDANCE
STILL SHOWING STRATUS OVER THE AREA - WHICH MAY TEMPER HIGHS
SLIGHTLY. BREEZY, WITH GUSTS 35 MPH. VERY STRONG CAPPING REMAINS IN
PLACE SATURDAY AFTERNOON THROUGH SATURDAY NIGHT/EARLY SUNDAY, WHICH
SHOULD PROHIBIT WIDESPREAD STORMS. HOWEVER, IF A STORM CAN BREAK THE
CAP OR MOVE INTO OUR AREA, THERE IS AMPLE INSTABILITY AND SHEAR IN
ADDITION TO STEEP MID LEVEL LAPSE RATES. AN ISOLATED STRONG TO
SEVERE STORM IS POSSIBLE IF STORMS OVERCOME THE CAP, WITH WIND GUSTS
TO 60 MPH AND HAIL TO PING PONG BALL SIZE SATURDAY EVENING INTO
EARLY SUNDAY.
CONFIDENCE REMAINS HIGH WITH THE BUILDING HEAT AND HUMIDITY SUNDAY
INTO MID NEXT WEEK, WITH THE HOTTEST DAYS STILL PROGGED TO BE SUNDAY
AND MONDAY. ENSEMBLE PROBABILITIES OF TEMPERATURES ABOVE 90 DEGREES
REMAIN MODERATE TO VERY HIGH (ABOVE 50% TO NEAR 100%) BOTH SUNDAY
AND MONDAY. VERY WARM (POSSIBLY RECORD WARM) OVERNIGHT LOWS PROVIDE
LITTLE RELIEF AND DRIVE HEAT RISK INTO THE MAJOR AND EVEN EXTREME
CATEGORIES. PLAN AHEAD NOW TO LIMIT HEAT EXPOSURE, ESPECIALLY THOSE
WITH OUTDOOR PLANS AND VULNERABLE POPULATIONS/THOSE MORE SUSCEPTIBLE
TO HEAT ILLNESS.
DISCUSSION
ISSUED AT 215 PM CDT THU JUN 25 2026
CURRENTS & TONIGHT: BEAUTIFUL CONDITIONS CONTINUE! TAKING A LOOK
ACROSS THE AREA, FALL-LIKE CONDITIONS CONTINUE THIS AFTERNOON WITH
MANY SITES REPORTING TEMPERATURES IN THE LOW TO UPPER 70S WITH
LIGHTER WINDS AS OF 1 PM. WE'RE ALSO STARTING TO SEE SOME SCATTERED
SHOWERS PROGRESS INTO THE MISSOURI RIVER VALLEY MAINLY IN RESPONSE
TO WEAK SHORTWAVE AND WEAKENING LLJ. WHILE SEVERE WEATHER IS NOT
EXPECTED, COULD SEE THIS FESTERING ACTIVITY CONTINUE THROUGH THE
EARLY EVENING MAINLY ACROSS THE SAME AREAS BEFORE THINGS GRADUALLY
DISSIPATE WITH THE LOSS OF DIURNAL HEATING. OTHERWISE, COULD SEE
ADDITIONAL SHOWERS DEVELOP OVERNIGHT INTO FRIDAY MORNING AS ANOTHER
WAVE INTERACTS WITH A STRENGTHENING NOCTURNAL LLJ. LASTLY, MORE
SEASONABLE TEMPERATURES ARE EXPECTED OVERNIGHT AS LOWS FALL
INTO THE MID TO UPPER 50S FOR THE NIGHT.
THE WEEKEND: LOOKING INTO THE WEEKEND, WE'LL CONTINUE TO SEE A FEW
LINGERING SHOWERS IN OUR FAR NORTHWESTERN ZONES TO START THE DAY ON
FRIDAY. AS THE LLJ WEAKENS, THIS ACTIVITY SHOULD GRADUALLY DIMINISH
BY MID-MORNING. QUIETER CONDITIONS WILL RETURN FOR THE REST OF
FRIDAY INTO THE FIRST HALF OF SATURDAY AS HIGHS CONTINUE TO SIT IN
THE LOW TO MID 80S. OTHERWISE, CLOUD COVER WILL GRADUALLY BUILD
DURING THE DAY ON SATURDAY AS WARM AIR ADVECTION (WAA) STRENGTHENS.
WITH SOUTHWESTERLY FLOW IN PLACE ALOFT, INCREASES IN ISENTROPIC LIFT
WITH AN APPROACHING WAVE COULD LEAD TO A FEW POCKETS OF DRIZZLE TO
LIGHT SHOWER DEVELOPING IN THE LOWER CLOUD DECK. HOWEVER, SEVERE
WEATHER IS NOT EXPECTED MAINLY DUE TO STRONG CAP ACCORDING TO
SOUNDINGS. LOOKING INTO SUNDAY, THE FOCUS WILL SHIFT TO THE BUILDING
HEAT AS SOUTHERLY SURFACE WINDS AND INCREASING MID-LEVEL WAA LEADS
TO A PUSH TOWARDS HIGHS MAINLY IN THE LOW TO UPPER 90S. THIS
COMBINED WITH DEW POINTS CLOSER TO UPPER 60S TO LOW 70S WILL LEAD TO
HEAT INDICES IN THE 90S TO LOW 100S FOR PARTS OF THE AREA WITH THE
WARMEST CONDITIONS ACROSS NORTHWESTERN IA. WHILE A HEAT HEADLINE
COULD BE NEEDED, DECIDED TO FORGO IT AT THIS TIME MAINLY DUE TO
UNCERTAINTY WITH SPACIAL EXTENT. NONETHELESS, WITH MUGGY CONDITIONS
EXPECTED THROUGH SUNDAY EVENING MAKE SURE TO STAY HYDRATED AND TO
LIMIT ANY STRENUOUS ACTIVITIES!
NEXT WEEK: HEADING INTO THE EXTENDED PERIOD, THE FOCUS WILL CONTINUE
TO BE ON THE HEAT AS UPPER-LEVEL RIDGING CONTINUES TO BUILD OVER THE
EASTERN CONUS. WITH SOUTHERLY SURFACE WINDS IN PLACE AND MULTIPLE
PUSHES OF WARMER AIR ALOFT, EXPECT TEMPERATURES TO CONTINUE TO HOVER
IN THE LOW TO UPPER 90S FROM MONDAY ONWARDS WITH HEAT INDICES (HI)
IN THE 90S TO LOW 100S DEGREE MARKS AT TIMES. WHILE CONDITIONS WON'T
QUITE MAKE IT INTO EXCESSIVE HEAT TERRITORY, WE COULD SEE MANY AREAS
TOUCH HEAT ADVISORY CRITERIA (HI>100) AT TIMES EACH DAY SO THIS WILL
BE SOMETHING TO WATCH MOVING FORWARD. EITHER WAY, THE CONDITIONS
WILL LEAD TO MODERATE TO MAJOR HEAT RISK FOR MOST AREAS FROM MONDAY
THROUGH WEDNESDAY SO MAKE SURE TO DRINK PLENTY OF WATER AND TO TAKE
PLENTY OF BREAKS WHEN WORKING OUTDOORS! OTHERWISE, WE'LL ALSO HAVE
TO KEEP ANY EYE TO THE SKIES THROUGH MIDWEEK AS SOUTH-SOUTHWESTERLY
FLOW ALOFT HELP USHERS IN MULTIPLE PIECES OF ENERGY INTO THE AREA
THROUGH WEAK PERTURBATION. WITH PLENTY OF HEAT IN THE FORECAST, ALL
THAT'S NEEDED IS A STRONG ENOUGH TRIGGER TO BREAK THROUGH THE CAP TO
GET SOMETHING STRONG TO SEVERE. NONETHELESS, ITS STILL UNCERTAIN IF
THIS CAN HAPPEN GIVEN THE WARMER TEMPERATURES +20 TO +28 DEGREES C
AT 800 MB THROUGH MIDWEEK. WITH ALL THIS IN MIND, MAKE SURE TO
MONITOR YOUR LOCAL FORECAST AS THINGS WILL BE SUBJECT TO CHANGE
MOVING FORWARD.
AVIATION /12Z TAFS THROUGH 12Z SATURDAY/
ISSUED AT 625 AM CDT FRI JUN 26 2026
SEEING SOME BRIEF AND LOCALIZED MVFR CONDITIONS THIS MORNING
WITH HEAVIER SHOWERS. OTHERWISE, VFR CONDITIONS EXPECTED THROUGH
THE PERIOD AS SHOWERS AND SPRINKLES DIMINISH LATE THIS MORNING.
SOME ENSEMBLE GUIDANCE HINTS AT MVFR STRATUS MOVING INTO THE
SOUTHERN MO RIVER VALLEY, INCLUDING KSUX, BY THE END OF THE
PERIOD; HOWEVER, WITH LOW CONFIDENCE HAVE OMITTED AT THIS TIME.
WINDS THROUGH THE DAY BECOME SOUTHEASTERLY WITH GUSTS AROUND 20
TO 25 KNOTS THROUGH MUCH OF THE PERIOD, INCLUDING INTO THE
OVERNIGHT HOURS - MAINLY WEST OF THE JAMES RIVER.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...SG
DISCUSSION...05
AVIATION...SG
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