662
FXUS63 KFSD 220900
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
400 AM CDT SUN JUN 22 2025
KEY MESSAGES
- THE DANGEROUS HEAT CONTINUES TODAY WITH AFTERNOON/EVENING HEAT
INDICES AVERAGING 100-110 DEGREES. HEAT HEADLINES WERE
EXPANDED SLIGHTLY TO THE WEST.
- BREEZY SOUTHERLY WINDS WILL CONTINUE TODAY WITH GUSTS BETWEEN
25-40 MPH AT TIMES. WHILE THE FIRE WEATHER CONCERNS SHOULD BE
KEPT TO A MINIMUM, LOCALLY ELEVATED CONCERNS WILL BE POSSIBLE
IN THE AREAS WHICH HAVE RECEIVED LIMITED RAINFALL OVER THE
PAST WEEK.
- THE RISK FOR SEVERE STORMS RETURNS THIS EVENING INTO THE
OVERNIGHT NIGHT HOURS WITH THE PRIMARY RISKS BEING LARGE HAIL
AND STRONG WIND GUSTS. LOCALLY HEAVY DOWNPOURS WILL BE A
SECONDARY RISK.
- AN ACTIVE PATTERN ALOFT WILL CONTINUE FOR MUCH OF THE NEW
WEEK. WHILE SOME UNCERTAINTY REMAINS, A FAVORABLE SET UP ALOFT
WILL LEAD TO MULTIPLE CHANCES FOR SHOWERS AND THUNDERSTORMS
ALONG WITH LOCALLY HEAVY RAINFALL DURING THE MIDWEEK.
DISCUSSION
ISSUED AT 353 AM CDT SUN JUN 22 2025
ANOTHER VERY WARM NIGHT ACROSS THE REGION WITH TEMPERATURES AS OF 3
AM IN THE LOWER TO MID 80S - WHICH IS TYPICAL OF HIGHS FOR THIS TIME
OF YEAR. CURRENTLY SEEING A FEW ISOLATED ELEVATED
SHOWERS/THUNDERSTORMS WEST OF THE JAMES RIVER VALLEY - THIS IN
ASSOCIATION WITH CONVERGENCE ALONG THE NOSE OF A LOW LEVEL JET AND A
WEAK SHORTWAVE LIFTING INTO THE AREA. LATEST HI-RES GUIDANCE WOULD
SUGGEST THESE ISOLATED STORM LIFTING NORTHEAST INTO EAST CENTRAL SD
THROUGH THE EARLY MORNING HOURS BEFORE EXITING THE AREA AROUND 12Z.
ONE MORE HOT DAY IN STORE ACROSS THE REGION WITH TEMPERATURES WELL
INTO THE 90S TO NEAR 100 FOR MUCH OF AREA. THE EXCEPTION WILL BE
OVER SOUTH CENTRAL SD WHERE HIGHS WILL REMAIN IN THE LOWER TO MID
90S - THIS AS A COLD FRONT DRIFTS EASTWARD INTO THE AREA DURING THE
AFTERNOON AS LOW PRESSURE LIFTS THROUGH CENTRAL SD INTO NORTHEASTERN
SD THROUGH THE DAY. WITH DEW POINTS IN THE UPPER 60S TO LOWER 70S,
HEAT INDICES WILL AGAIN RUN FROM 100 TO 110 IN THE AFTERNOON, AND
EXPANDED THE HEAT HEADLINES SLIGHTLY WESTWARD TO INCLUDE A FEW
COUNTIES THROUGH THE WESTERN JAMES RIVER VALLEY. SOUNDINGS AGAIN
INDICATE STRONG CAPPING IN PLACE ACROSS THE REGION, SO LOOKING FOR
DRY CONDITIONS THROUGH MOST OF THE DAY.
CHANGES FINALLY COME BY THIS EVENING AS THE NEXT SHORTWAVE DRIFTS
NORTHWARD AND LIFT INCREASES AS AN UPPER LEVEL JET SHIFTS INTO
CENTRAL SD. IN RESPONSE, THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER
SOUTH CENTRAL SD INITIALLY, EXPANDING TO THE NORTHEAST ALONG THE
FRONT INTO THE JAMES RIVER VALLEY DURING THE EARLY TO MID EVENING.
SOUNDINGS INDICATE MUCAPE JUST EITHER SIDE OF 3000 J/KG AND
EFFECTIVE SHEAR OF 20 TO 30 KTS IN THE VICINITY AT THAT TIME, AND
WITH MIDLEVEL LAPSE RATES OF AROUND 7 DEGREES C/KM A FEW STORMS ARE
EXPECTED TO BECOME SEVERE WITH HAIL POSSIBLY AS LARGE AS GOLF BALLS.
DCAPE WILL BE RUNNING AROUND 1500-2000 J/KG, SO WIND GUSTS UP TO 70
MPH WILL BE POSSIBLE WITH ANY STRONGER STORM. HI RES GUIDANCE HAS
THE STORMS TRANSITIONING TO THE NORTH AND EAST THROUGH THE NIGHT
TIME HOURS, WEAKENING AS AS INSTABILITY WANES DURING THE NIGHT. THE
MAIN THREAT TIME FOR SEVERE STORMS WILL COME BETWEEN 7PM TO 1 AM. AS
THE FRONT MOVES EASTWARD OVERNIGHT, COOLER AIR WILL FEED INTO THE
AREA, AND LOWS WILL DROP DOWN INTO THE 60S TO LOWER 70S.
THE FRONTAL BOUNDARY WILL DROP INTO SOUTHERN IA AND NE ON MONDAY,
THOUGH ADDITIONAL SHOWERS AND THUNDERSTORMS WILL BE LIKELY OVER
NORTHWESTERN IA BY THE AFTERNOON AND EVENING IN THE VICINITY OF THE
850 MB FRONT. WITH LINGERING MUCAPE OF AROUND 1200 J/KG AND
EFFECTIVE SHEAR AROUND 30 KTS OVER THAT AREA, CANNOT RULE OUT
ISOLATED STRONG TO SEVERE STORMS THROUGH EARLY EVENING. IN THE
COOLER AIRMASS BEHIND THE AFOREMENTIONED FRONT, HIGHS WILL ONLY BE
IN THE UPPER 70S TO LOWER 80S. IN ADDITION, IT WILL FEEL MUCH MORE
COMFORTABLE OVER MOST OF THE AREA AS DEW POINTS FALL INTO THE 40S
AND 50S (THOUGH REMAINING IN THE 60S OVER PARTS OF NORTHWEST IA).
MODELS ARE IN GOOD AGREEMENT ON UNSETTLED WEATHER CONTINUING FOR
MUCH OF NEXT WEEK WITH THE AFOREMENTIONED UPPER LEVEL JET ONLY
SLOWLY SHIFTING TO THE NORTHEAST AND THE FRONTAL BOUNDARY MEANDERING
ACROSS THE REGION THROUGH THE WEEK. OUR AREA WILL REMAIN IN A
SOUTHWESTERLY UPPER LEVEL FLOW THROUGH THE PERIOD AS A TROUGH
PERSISTS OVER THE WESTERN CONUS, AND THE BOUNDARY MAY BE THE FOCUS
FOR SHOWERS AND STORMS AS A SERIES OF SHORTWAVES TRAVERSE THE
SOUTHWESTERLY UPPER LEVEL FLOW. THIS COULD RESULT IN PERIODIC SEVERE
WEATHER CHANCES ALONG WITH HEAVY RAIN CHANCES AND LOCALIZED FLASH
FLOODING - FOCUSED ON TUESDAY NIGHT AND WEDNESDAY NIGHT AS OUTLINED
IN THE WPC ERO. THIS IS SUPPORTED BY ECMWF AND NAEFS ENSEMBLES
INDICATING PWAT VALUES IN THE 99TH PERCENTILE WITH RESPECT TO
CLIMATOLOGY FOR LATE MONDAY INTO WEDNESDAY (GENERALLY RUNNING 1.5"
TO 2"+ THROUGH THE PERIOD). ENSEMBLES CONTINUE TO SUGGEST THE HIGHER
RAINFALL TOTALS THROUGH THE WEEK WILL RESIDE OVER SOUTHERN SD,
NORTHERN NE AND NORTHERN IA. IN TERMS OF RAINFALL TOTALS OVER THAT
AREA INTO THURSDAY, WHILE GENERAL AMOUNTS GREATER THAN 2" ARE A GOOD
BET (ENSEMBLE PROBABILITIES OF 60-80%), PROBABILITIES OF 3" TO 4"
ARE A LITTLE LOWER (30-40% AND 10-20% RESPECTIVELY). OF NOTE, THESE
ARE AREA WIDE AVERAGES AND LOCAL AMOUNTS COULD BE HIGHER.
TEMPERATURES THROUGH MID WEEK LOOK TO BE JUST EITHER SIDE OF NORMAL
(HIGHS MID 70S TO LOWER 80S), THEN TRENDING UPWARDS TO ABOVE AVERAGE
(MID 80S TO NEAR 90) FOR THE END OF THE WEEK. IT APPEARS THAT
RAINFALL CHANCES WILL DECREASE TOWARD THE END OF THE WEEK (THURSDAY
THROUGH SATURDAY) AS THE UPPER LEVEL JET FINALLY SHIFTS OFF TO THE
NORTHEAST AND THE UPPER LEVEL FLOW BECOMES LESS AMPLIFIED.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1057 PM CDT SAT JUN 21 2025
ISOLATED SHOWERS AND STORMS ARE POSSIBLE TONIGHT, MAINLY WEST OF I-
29. MOST OF US WILL REMAIN DRY, BUT THERE WAS ENOUGH OF A CHANCE TO
WARRANT KEEPING THE PROB30 GROUP AT KHON BETWEEN 09-12Z. ANY OF
THESE SHOWERS COULD PRODUCE GUSTY WINDS, EVEN WITHOUT THUNDER. MOST
OF THE DAY SUNDAY WILL BE DRY, BUT SCATTERED SHOWERS AND STORMS LOOK
TO DEVELOP AROUND 00-02Z IN SOUTH-CENTRAL SOUTH DAKOTA AND QUICKLY
MOVE NORTHEAST THROUGH THE END OF THE PERIOD. THERE IS STILL SOME
UNCERTAINTY IN THE EXACT LOCATION OF STORM DEVELOPMENT, BUT THERE
WAS ENOUGH CONFIDENCE TO INCLUDE A PROB30 GROUP FOR KHON BETWEEN 01-
04Z SUNDAY NIGHT, AND NOT ENOUGH CONFIDENCE TO INCLUDE A STORM
THREAT AT KFSD AT THIS TIME.
LLWS CONCERNS CONTINUE TONIGHT FOR KFSD AND KSUX, AND WILL APPEAR
AGAIN FOR KSUX BY 02Z SUNDAY NIGHT. WINDS WILL PICK UP AGAIN DURING
THE DAY ON SUNDAY, WITH PEAK GUSTS AROUND 30-35 KTS ESPECIALLY ALONG
AND EAST OF THE JAMES RIVER. A COLD FRONT WILL BEGIN TO MOVE INTO
THE AREA FROM WEST TO EAST STARTING SUNDAY AFTERNOON, WHICH WILL
BEGIN TO TURN THE WINDS NORTHWESTERLY.
FSD WATCHES/WARNINGS/ADVISORIES
SD...EXTREME HEAT WARNING UNTIL 9 PM CDT THIS EVENING FOR SDZ061-
062-065>071.
HEAT ADVISORY FROM 1 PM THIS AFTERNOON TO 7 PM CDT THIS
EVENING FOR SDZ038-053-059-063-064.
HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR SDZ039-040-
054>056-060.
MN...EXTREME HEAT WARNING UNTIL 9 PM CDT THIS EVENING FOR MNZ071-
072-080-081-089-090-097-098.
IA...EXTREME HEAT WARNING UNTIL 9 PM CDT THIS EVENING FOR
IAZ001>003-012>014-020>022-031-032.
NE...EXTREME HEAT WARNING UNTIL 9 PM CDT THIS EVENING FOR NEZ013-
014.
DISCUSSION...JM
AVIATION...SAMET
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