064
FXUS63 KFSD 270912
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
412 AM CDT SAT JUN 27 2026
KEY MESSAGES
- SUMMER HEAT AND HUMIDITY WILL MAKE ITS RETURN STARTING SUNDAY
INTO NEXT WEEK. HEAT INDICES UP TO THE LOW 100S WILL LEAD TO
MAJOR TO LOCALLY EXTREME HEAT RISK AT TIMES. BEGIN PLANNING
NOW TO REDUCE THE RISK OF HEAT ILLNESS AND IMPACTS.
- A HEAT ADVISORY HAS BEEN ISSUED FOR SOME AREAS SUNDAY INTO
MONDAY, AND FURTHER ADJUSTMENTS TO HEADLINES ARE LIKELY IN THE
COMING DAYS.
- A FEW STRONG TO SEVERE STORMS WILL BE POSSIBLE LATE TONIGHT
INTO SUNDAY MORNING. PRIMARY RISKS WOULD BE UP TO GOLF BALL
SIZED HAIL AND ISOLATED DAMAGING WINDS UP TO 65 MPH.
- AN ACTIVE PATTERN ALOFT COULD LEAD TO ADDITIONAL CHANCES FOR
STRONGER STORMS FROM EARLY TO MID NEXT WEEK. HOWEVER, SOME
UNCERTAINTY STILL REMAINS.
UPDATE
ISSUED AT 410 AM CDT SAT JUN 27 2026
MOIST SOUTHEAST FLOW WILL LEAD TO INCREASING STRATUS ACROSS THE
AREA THIS MORNING, WITH SOME QUESTION REGARDING HOW QUICKLY THE
STRATUS WILL CLEAR AND ALLOW SUFFICIENT WARMING. IF THE CLOUDS
PERSIST LONGER, HIGH TEMPERATURES TODAY MAY BE A BIT OPTIMISTIC.
HOWEVER, DUE TO LOW CONFIDENCE IN THE STRATUS EVOLUTION, DID NOT
STRAY TOO FAR FROM THE NBM PROJECTIONS.
WHILE HIGHS FOR SUNDAY HAVE TRENDED LOWER THAN RECENT FORECASTS,
ROBUST HUMIDITY LEVELS COMBINED WITH HIGHS IN THE MID-UPPER 90S
STILL LEAD TO HIGH CONFIDENCE THAT PORTIONS OF SOUTHEAST SOUTH
DAKOTA, NORTHWEST IOWA AND NORTHEAST NEBRASKA WILL SEE TRIPLE
DIGIT HEAT INDICES SUNDAY. LOWER CONFIDENCE IN TEMPERATURES FOR
AREAS NORTH OF I-90 DUE TO POTENTIAL IMPACTS FROM EARLY MORNING
CONVECTION, SO OPTED TO HOLD OFF ON HEADLINES ACROSS SOUTHWEST
MINNESOTA FOR NOW, THOUGH SOME LOCATIONS THERE MAY ALSO BRIEFLY
PUSH TOWARD HEAT ADVISORY CRITERIA SUNDAY AFTERNOON.
CONFIDENCE IN HIGHS ON MONDAY ARE ON THE LOWER SIDE AS RECENT
NBM FORECAST NEAR THE 90TH PERCENTILE OF THE BROADER LONG-RANGE
ENSEMBLE TEMPERATURES. AS A RESULT, HAVE NUDGED HIGHS MONDAY
DOWN A BIT ACROSS CENTRAL/EASTERN PORTIONS OF THE FORECAST AREA.
THIS STILL YIELDS HEAT INDICES OF 100-105F FOR MANY AREAS ALONG
AND EAST OF A YANKTON-SIOUX FALLS-MARSHALL LINE. THE SD/NE/IA
PORTIONS OF THAT AREA WILL SEE MONDAY MORNING LOW TEMPERATURES
REMAINING ABOVE 75F, FOLLOWED BY A SECOND DAY OF TRIPLE DIGIT
HEAT INDICES IN THE AFTERNOON, SO DECIDED TO CARRY THE HEAT
ADVISORY FROM SUNDAY AFTERNOON ALL THE WAY THROUGH EARLY MONDAY
EVENING FOR YANKTON-SIOUX FALLS AND POINTS EAST INTO NORTHWEST
IOWA. IT'S POSSIBLE THAT THIS MAY NEED TO BE EXPANDED NORTH INTO
SOUTHWEST MINNESOTA, BUT GIVEN UNCERTAINTY WITH THE TEMPERATURE
FORECAST 3 DAYS OUT, OPTED TO HOLD OFF ON THIS FOR NOW.
STORM CHANCES LOOK TO BE FOCUSED LATE TONIGHT INTO EARLY SUNDAY
MORNING AS STORM CLUSTERS MOVE EAST FROM THE HIGH PLAINS AFTER
MIDNIGHT. SOUNDINGS INDICATE A STRONG SURFACE-BASED INVERSION,
SO PRIMARY THREAT FROM STRONGER ELEVATED STORMS LOOKS TO BE
LARGE HAIL IN RESPONSE TO STEEP MID-LEVEL LAPSE RATES, THOUGH
WARM CLOUD DEPTHS WELL IN EXCESS OF 10-12KFT AGL IN A WARMING
ENVIRONMENT COULD LIMIT HAIL SIZES.
AFTER STORMS EXIT BY MID-MORNING SUNDAY, THE REST OF SUNDAY INTO
MONDAY MORNING LOOKS QUIET. LATE MONDAY-MONDAY EVENING COULD
BRING THE NEXT ROUND OF POTENTIAL SEVERE WEATHER, BUT AS NOTED
IN THE SPC DAY 3 OUTLOOK, THIS RISK IS CONDITIONAL ON STORM
DEVELOPMENT WHICH IS STILL UNCERTAIN WITH A MODERATE-STRONG
CAPPING INVERSION ACROSS THE AREA.
DISCUSSION
ISSUED AT 222 PM CDT FRI JUN 26 2026
CURRENTS & TONIGHT: A WARM AND BREEZY DAY CONTINUES! TAKING A LOOK
ACROSS THE AREA, WE'RE CONTINUING TO SEE A FEW SPRINKLES TO VERY
LIGHT SHOWERS LIFT OUT OF PORTIONS OF FAR EASTERN SD AND SOUTHWESTERN
MN THIS AFTERNOON WITH MAINLY LIGHT ACCUMULATIONS. WHILE THIS VERY
LIGHT ACTIVITY COULD PERSIST FOR THE NEXT HOUR OR TWO, SHOULD SEE
MOST OF THIS ACTIVITY PUSH OUT OF OUR AREA BY LATE AFTERNOON. FROM
HERE, MOSTLY QUIET CONDITIONS WILL RETURN AS CLOUD COVER THINS INTO
THE EVENING HOURS. OTHERWISE, WEAK MID-LEVEL RIDGE WILL SHIFT OUR
QUASI-ZONAL FLOW ALOFT BACK TO MORE SOUTHWESTERLY OVERNIGHT SETTING
THE STAGE FOR OUR NEXT PRECIPITATION CHANCES FROM SATURDAY INTO
SUNDAY. LASTLY, A WARMER NIGHT WILL BE ON TAP AS OVERNIGHT LOWS ONLY
FALL INTO THE UPPER 50S TO MID 60S.
SATURDAY & SUNDAY: LOOKING INTO THE REST OF THE WEEKEND, QUIETER
CONDITIONS WILL TEMPORARILY RETURN BY SATURDAY AS WEAK RIDGING MOVE
OVERHEAD. CLOUD COVER WILL GRADUALLY INCREASE DURING THE DAY AS A
LIFTING WARM FRONT BRINGING IN STRENGTHENING WARM AIR ADVECTION
(WAA). THIS COMBINED WITH DEEPER MIXING AND A TIGHTENING SPG WILL
NOT ONLY LEAD TO THE RETURN OF BREEZY SOUTHEASTERLY WINDS, BUT ALSO
A SLIGHT BUMP IN TEMPERATURES WITH HIGHS PEAKING IN UPPER 70S TO MID
80S. LOOKING ALOFT, SOUTHWESTERLY FLOW WILL LEAD TO MULTIPLE PIECES
OF ENERGY LIFTING OUT OF THE BLACK HILLS INTO NORTHEASTERN SD. WHILE
WE CAN'T COMPLETELY RULE OUT SOME ISOLATED SHOWERS IN OUR FAR
NORTHWEST DURING THE AFTERNOON, THE MAIN CONCERNS WILL DEVELOP FROM
SATURDAY EVENING INTO SUNDAY MORNING AS A DEVELOPING TRIPLE POINT
LIFTS OUT OF THE NEBRASKA PANHANDLE WITH A SURFACE LOW. GIVEN THE
SLIGHTLY WEAKER CAP AND STRENGTHENING LLJ, CURRENT THOUGHTS ARE THAT
THE INCREASING FORCING WITH THE TRIPLE POINT COULD BE ENOUGH TO
BREAK THE CAP AND GENERATE A FEW THUNDERSTORMS BY SUNDAY MORNING.
IF STORMS CAN DEVELOP, THEY COULD BECOME STRONG WITH A DECENTLY
UNSTABLE ENVIRONMENT CHARACTERIZED BY AROUND 1200-1800 J/KG OF CAPE
AND AROUND 40-50 KTS OF 0-6 KM BULK SHEAR. STRONGER STORMS WOULD BE
CAPABLE OF PRODUCING UP TO GOLF-BALL SIZED HAIL AND DAMAGING WIND
GUSTS UP TO 65 MPH. NONETHELESS, THERE ARE STILL SOME LOCATIONAL
DIFFERENCES BETWEEN SHORT-RANGE GUIDANCE SO ITS A BIT HARD TO PIN
DOWN A SPECIFIC AREA OF FOCUS RIGHT NOW. WITH ALL THIS IN MIND, MOST
OF OUR AREA IS NOW OUTLINED IN AN SPC DAY 2 MARGINAL RISK (LEVEL 1
OF 5) FOR SEVERE WEATHER SO MAKE SURE TO MULTIPLE WAYS TO RECEIVE
WARNING INFORMATION! FROM HERE, QUIETER CONDITIONS SHOULD RETURN
FROM LATE MORNING ONWARDS AS THE UPPER-LEVEL RIDGE STRENGTHENS
SETTING THE STAGE FOR A RETURN OF DANGEROUS HEAT. WHILE THE EARLY
MORNING STORMS COULD POTENTIALLY AFFECT OUR TEMPERATURES, SOUTHERLY
SURFACE WINDS COMBINED WITH A PUSH OF STRONG WWA ALOFT COULD BOOST
OUR HIGHS TO THE LOW TO UPPER 90S WITH HEAT INDICES IN THE 90S TO
LOW 100S. WHILE THIS WOULD FALL INTO OUR HEAT ADVISORY CRITERIA,
WILL LIKELY WAIT UNTIL THINGS GET CLOSER TO FINALIZE ANY TYPE OF
HEAT HEADLINE. LASTLY, GIVEN THE WARMER OVERNIGHT TEMPERATURES (60S-
70S); WE'LL HAVE TO BE ON THE LOOKOUT FOR A FEW RECORD WARM LOWS
ACROSS THE AREA FROM SUNDAY INTO MONDAY (CHECK CLIMATE SECTION
BELOW.)
NEXT WEEK: HEADING INTO THE NEW WEEK, 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 THURSDAY SO MAKE SURE TO DRINK PLENTY OF WATER AND TO LIMIT
ANY STRENUOUS ACTIVITIES! OTHERWISE, WE'LL ALSO HAVE TO KEEP ANY EYE
TO THE SKIES THROUGH LATE WEEK AS SOUTH-SOUTHWESTERLY FLOW ALOFT
HELPS USHERS IN MULTIPLE PIECES OF ENERGY INTO THE AREA THROUGH WEAK
PERTURBATIONS. WITH PLENTY OF HEAT IN THE FORECAST, ALL THAT WOULD
BE NEEDED IS A STRONG ENOUGH TRIGGER TO BREAK THROUGH THE CAP TO GET
SOMETHING STRONG TO SEVERE. WHILE THE PROBABILITIES OF THIS ARE LOW
(30% OR LESS) AT THIS TIME, THE CHANCES AREN'T ZERO EITHER SO MAKE
SURE TO MONITOR YOU LOCAL FORECAST FOR THE LATEST CHANGES.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 1249 AM CDT SAT JUN 27 2026
LOW VFR TO MVFR STRATUS HAS DEVELOPED OVER SOUTHERN IOWA AND
EASTERN NEBRASKA TO START THE PERIOD, AND THIS AREA OF STRATUS LOOKS
TO LIFT NORTH THROUGH OUR AREA AND LOWER TO MVFR TO LOCALLY IFR
LEVELS HEADING TOWARDS DAYBREAK. THIS STRATUS DECK THEN LOOKS
TO LIFT AND ERODE AS WE HEAD INTO THE LATE MORNING TO EARLY
AFTERNOON HOURS TODAY. SHOWERS AND STORMS WILL DEVELOP OFF TO
OUR WEST LATE THIS AFTERNOON AND EARLY EVENING AND THEN MOVE
INTO CENTRAL SOUTH DAKOTA TOWARDS THE END OF THE PERIOD. SOME
UNCERTAINTY AS TO WHETHER OR NOT THESE RAIN CHANCES ARRIVE AT
KHON EITHER AT THE VERY END OF THE PERIOD OR JUST AFTERWARDS, SO
LEFT OUT ANY MENTION AT THIS TIME.
WINDS WILL BE OUT OF THE SOUTHEAST THROUGH THE PERIOD, WITH WINDS
QUICKLY INCREASING THROUGH THE MORNING HOURS. WINDS COULD GUST AS
HIGH AS 25-35 KTS WEST OF I-29 THIS AFTERNOON, GENERALLY STRONGER
WITH WESTWARD EXTENT. EAST OF I-29, WINDS WILL GUST TO AS HIGH AS 20-
30 KTS IN THE AFTERNOON, GENERALLY LOWER WITH EASTWARD EXTENT.
BREEZY WINDS WILL CONTINUE THROUGH THE END OF THE PERIOD.
CLIMATE
ISSUED AT 410 AM CDT SAT JUN 27 2026
SUMMER HEAT BUILDS INTO THE AREA FROM SUNDAY THROUGH MUCH OF
NEXT WEEK. THIS WILL LEAD TO A POTENTIAL FOR A FEW TEMPERATURE
RECORDS TO BE TIED, OR POSSIBLY BROKEN:
CURRENT RECORD HIGHS:
MONDAY (06/29): KFSD(101|2002) KSUX(100|2022)
CURRENT RECORD WARM LOWS:
MONDAY (06/29): KFSD(77|2020) KSUX(80|1931) KHON(75|2020)
FSD WATCHES/WARNINGS/ADVISORIES
SD...HEAT ADVISORY FROM 1 PM SUNDAY TO 9 PM CDT MONDAY FOR SDZ062-
066-067-069>071.
HEAT ADVISORY FROM 1 PM TO 9 PM CDT SUNDAY FOR SDZ060-061-065-
068.
MN...NONE.
IA...HEAT ADVISORY FROM 1 PM SUNDAY TO 9 PM CDT MONDAY FOR
IAZ001>003-012>014-020>022-031-032.
NE...HEAT ADVISORY FROM 1 PM SUNDAY TO 9 PM CDT MONDAY FOR NEZ013-
014.
UPDATE...JH
DISCUSSION...05
AVIATION...SAMET
CLIMATE...JH
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