215
FXUS63 KFSD 150302
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1002 PM CDT FRI AUG 14 2026
KEY MESSAGES
- LOW STRATUS AND FOG REMAIN POSSIBLE TONIGHT INTO SATURDAY
NIGHT. LOWER CONFIDENCE FOR STRATUS AND FOG SUNDAY INTO SUNDAY
NIGHT WITH A SMALL PUSH OF DRIER AIR.
- SCATTERED SHOWERS AND A FEW STORMS ARE LIKELY TO DEVELOP
SATURDAY AFTERNOON ESPECIALLY NEAR AND EAST OF I-29. HEAVY
RAINFALL WILL BE THE MAIN CONCERN, BUT A WIND GUST TO 45 MPH
CAN'T BE RULED OUT IN THE STRONGEST STORM.
- MONDAY NIGHT INTO TUESDAY NIGHT IS THE NEXT BETTER CHANCE FOR
SHOWERS AND THUNDERSTORMS. ISOLATED SEVERE STORMS AND POCKETS
OF HEAVY RAIN WILL BE POSSIBLE.
UPDATE
ISSUED AT 953 PM CDT FRI AUG 14 2026
AMPLE MOISTURE ACROSS THE AREA WILL LEAD TO THE CONTINUED
DEVELOPMENT OF LOW STRATUS AND EVEN SOME FOG AFTER MIDNIGHT.
LOCALLY DENSE FOG WILL BE POSSIBLE ESPECIALLY WHERE SKIES CAN
CLEAR UP A BIT. MAKE SURE TO USE EXTRA CAUTION ON THE ROADS
TOMORROW MORNING AS VISIBILITIES MAY BE FINE IN YOUR LOCATION
BUT NOT IN THE PLACE YOU ARE HEADING TO! ANY FOG SHOULD LIFT BY
9 AM. DUE TO CLOUD COVER, TEMPERATURES WON'T FALL ALL THAT MUCH
OVERNIGHT, WITH LOWS BY SUNRISE MAINLY IN THE MIDDLE TO UPPER
60S.
LOW CLOUDS THAT LINGER INTO THE MORNING HOURS WILL BEGIN TO LIFT AND
ERODE BY THE LATE MORNING AND INTO THE EARLY AFTERNOON. THE SUNSHINE
THAT BREAKS THROUGH THESE CLOUDS SHOULD PROVIDE EFFICIENT
DESTABILIZATION IN THE AFTERNOON AS A WEAK WAVE AND COOL FRONT MOVES
ACROSS THE AREA. THIS WILL LEAD TO SHOWER AND STORM DEVELOPMENT
ESPECIALLY NEAR AND EAST OF I-29 WHERE THE FRONT MOVES THROUGH
CLOSEST TO PEAK DAYTIME HEATING. THERE WILL BE LITTLE CIN AND
AROUND 1,000 TO 2,000 J/KG OF SBCAPE, WITH CAPE PROFILES ONCE
AGAIN FAVORING HEAVY RAIN AS THE MAIN THREAT. SOME OF THE CAMS
ARE SHOWING SOME PRETTY HIGH RAINFALL RATES (POTENTIALLY UP TO
2" AN HOUR); BUT THIS ACTIVITY SHOULD BE PROGRESSIVE ENOUGH TO
PRECLUDE FLASH FLOODING CONCERNS. BUT BE PREPARED TO TAKE IT
SLOW ON THE ROADS IF DRIVING THROUGH THIS HEAVY RAIN!
SHEAR WILL BE A BIT BETTER SATURDAY THAN WHAT WE HAD TODAY, BUT
STILL FAIRLY WEAK OVERALL AND SO THIS SHOULD LIMIT SEVERE
POTENTIAL. BUT WITH BETTER INSTABILITY AND A BIT OF DRY MID
LEVEL AIR, CAN'T RULE OUT A WIND GUST TO 45 MPH ESPECIALLY
SOUTH OF I-90 WHERE THE BETTER INSTABILITY LIES. IF MORNING
CLOUDS TAKE A BIT LONGER TO CLEAR, THEN THE CHANCE FOR HEAVIER
THUNDERSTORMS WILL BE LOWER. GUIDANCE ALSO HINTS THAT ADDITIONAL
SHOWERS AND ISOLATED THUNDERSTORMS MAY ALSO DEVELOP ALONG AN
850 MB BOUNDARY THAT WILL TRAIL THE COOL FRONT, BUT THIS WOULD
ONLY REALLY BE A VERY ISOLATED LIGHTNING CONCERN FOR THOSE WITH
OUTDOOR ACTIVITIES PLANNED.
DISCUSSION
ISSUED AT 1236 PM CDT FRI AUG 14 2026
LOW PRESSURE CONTINUES TO TRACK EAST NORTHEAST INTO WESTERN IA
THROUGH THIS AFTERNOON. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL BE POSSIBLE WITH THIS FEATURE. THE MAIN EFFECTS SHOULD BE THIS
AFTERNOON AND CONFINED TO AREAS NEAR AND SOUTH OF HIGHWAY 20 IN
NORTHWEST IA. WITH PWAT VALUES AROUND 1.75" TO 2", LOCALLY HEAVY
RAIN WILL BE POSSIBLE, ESPECIALLY NEAR THIS LOW PRESSURE ALONG AND
SOUTH OF HIGHWAY 20. SOME QUESTION MARKS SURROUND THE AIR MASS IN
WOODBURY AND IDA COUNTIES, LOCATIONS THAT HAVE RECEIVED THE MOST
RAINFALL THE PAST TWO DAYS, AS THE MORNING STRATIFORM RAINFALL SEEMS
TO BE PROVIDING SOME STABILITY TO THE AREA AND SUPPRESSING STRONGER
CONVECTIVE ACTIVITY. THE LATEST HI-RES MODELS CONTINUE TO TREND AWAY
FROM HEAVIER RAIN NEAR HIGHWAY 20, WITH MAINLY SPOTTY ACTIVITY
EXPECTED. A FEW DOWNPOURS COULD LEAD TO VERY LOCALIZED AMOUNTS
AROUND AN INCH OR SO, BUT FLASH FLOODING IS UNLIKELY. FARTHER
NORTHWEST, SPOTTY SHOWERS WILL BE POSSIBLE WITH WEAK, DIURNALLY
DRIVEN INSTABILITY. THE OVERALL EFFECTS OF THESE DIURNALLY DRIVEN
SHOWERS WILL BE LOW.
SATURDAY WILL LIKELY START WITH STRATUS AND FOG IN MANY LOCATIONS. A
WEAK WAVE WILL MOVE THROUGH THE AREA AND LIKELY LEAD TO SPOTTY
SHOWERS AND THUNDERSTORMS. SOME HINTS THAT THE BETTER INSTABILITY
(ABOUT 1000 J/KG) WILL BE NORTH OF I-90, BUT OVERALL WEAK SHEAR AND
13 KFT FREEZING LEVELS SUGGEST THAT POCKETS OF HEAVY RAIN WILL BE
THE MAIN THREAT.
BY SATURDAY NIGHT THIS WAVE WILL MOVE SOUTHEAST OF THE AREA, LEAVING
MAINLY DRY CONDITIONS IN PLACE FOR MUCH OF SATURDAY NIGHT INTO
SUNDAY MORNING. MODEL SOUNDINGS HINT AT THE POTENTIAL FOR SOME
MORNING FOG, BUT THE DEPTH OF THE LOW LEVEL MOIST LAYER LOOKS MUCH
SHALLOWER, SO A BETTER CHANCE TO BURN OFF IN THE MORNING. DRIER
NORTHERLY FLOW SHOULD LEAD TO A PLEASANT SUNDAY WITH HIGHS OF 75 TO
80 AND DEW POINTS LIKELY IN THE LOWER TO MID 60S FOR MOST LOCATIONS.
SUNDAY NIGHT INTO MONDAY SHOULD SEE MOSTLY DRY AND WARM CONDITIONS
CONTINUE. MONDAY NIGHT INTO TUESDAY NIGHT WILL BE THE NEXT BETTER
CHANCE FOR SHOWERS AND STORMS AS A TROUGH DIGS IN TO THE NORTH AND
NORTHEAST. FOR NOW, THE THREAT FOR SEVERE STORMS AND HEAVY RAIN
LOOKS LOW, BUT THIS WILL BE A TIME FRAME TO WATCH FOR CHANGES.
COOLER AND MORE STABLE AIR SHOULD SETTLE IN BEHIND THIS SYSTEM, WITH
HIGHS MOSTLY IN THE 70S THURSDAY AND FRIDAY AND ONLY ISOLATED
CHANCES FOR SHOWERS AND STORMS.
AVIATION /00Z TAFS THROUGH 00Z SUNDAY/
ISSUED AT 658 PM CDT FRI AUG 14 2026
MVFR TO IFR AND LOCALLY LIFR STRATUS WILL IMPACT THE AREA
THROUGH TONIGHT AND INTO TOMORROW MORNING. PATCHY FOG IS ALSO
POSSIBLE LATE TONIGHT AND INTO EARLY TOMORROW MORNING. THIS
STRATUS SHOULD GRADUALLY LIFT AND ERODE THROUGH THE EARLY
AFTERNOON HOURS ON SATURDAY GENERALLY FROM WEST TO EAST ACROSS
THE AREA.
THUNDER POTENTIAL WILL REMAIN VERY LOW THROUGH THE EARLY MORNING
HOURS TOMORROW, THOUGH A BETTER CHANCE OF SOME POP-UP
THUNDERSTORMS WILL BE FROM THE MID-MORNINNG ONWARDS. CONFIDENCE
IN THUNDER POTENTIAL REMAINS LOW FOR TOMORROW AFTERNOON, SO
LEFT OUT ANY MENTION IN THE TAFS AT THIS TIME.
WINDS WILL BE LIGHT AND VARIABLE THROUGH THE EARLY MORNING HOURS,
WITH A SLIGHT UPTICK IN WEST-NORTHWESTERLY WINDS DURING THE
AFTERNOON HOURS SATURDAY. HIGHEST GUSTS WILL ONLY BE AROUND 15 KTS
OR SLIGHTLY HIGHER SATURDAY AFTERNOON.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...SAMET
DISCUSSION...08
AVIATION...SAMET
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