624
FXUS63 KFSD 270910
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
410 AM CDT THU AUG 27 2026
KEY MESSAGES
- AREAS OF FOG WILL LEAD TO VARYING VISIBILITY THROUGH THE MORNING
COMMUTE, PERHAPS BELOW A MILE AT TIMES. FOG WILL BE MORE LIKELY
NEAR RIVERS/PONDS AND OTHER LOW-LYING AREAS.
- WARMER AND MORE HUMID AIR RETURNS FRIDAY THROUGH THE WEEKEND
WITH MODERATE (40-60%) CHANCES FOR STORMS BY LATER FRIDAY
EVENING INTO FRIDAY NIGHT.
- PERIODIC SHOWER AND STORM CHANCES CONTINUE THIS WEEKEND INTO
EARLY NEXT WEEK. CONFIDENCE ON ANY DETAILS IS LOW.
- TEMPERATURES WILL BE ABOVE NORMAL THIS WEEKEND INTO THE MIDDLE
OF NEXT WEEK. HIGHS LIKELY IN THE 90S SATURDAY AND POSSIBLY
SUNDAY.
UPDATE
ISSUED AT 410 AM CDT THU AUG 27 2026
AS TEMPERATURES DIP INTO THE MID 50S EARLY THIS MORNING, WE ARE
SEEING AREAS OF FOG AROUND THE AREA PER SATELLITE, AIRPORT OBS
AND WEB CAMS. DO NOT EXPECT WIDESPREAD DENSE FOG, BUT VARIABLE
CONDITIONS WITH LOCALIZED VISIBILITY BELOW A MILE ARE POSSIBLE
THROUGH THE MORNING COMMUTE.
THE REMAINDER OF THE FORECAST IS ON TRACK, WITH THE MAIN QUESTION
REVOLVING AROUND THE TIMING OF POTENTIAL STORMS FRIDAY INTO FRIDAY
NIGHT. AS MENTIONED IN THE LATEST SPC DAY 2 OUTLOOK, POTENTIAL FOR
DEVELOPMENT DURING THE AFTERNOON TO EARLY EVENING LOOKS TO BE ON
THE LOWER SIDE GIVEN DECENT CAPPING INVERSION, THOUGH DEPENDING ON
TIMING OF A LEAD MID-LEVEL WAVE, ISOLATED DEVELOPMENT IS NOT OUT
OF THE QUESTION. BETTER OVERALL STORM CHANCES MAY WAIT UNTIL LATER
IN THE EVENING AND OVERNIGHT, AS THE LOW LEVEL JET RAMPS UP AND
INTERACTS WITH A TRAILING PORTION OF THE MID-LEVEL WAVE. IN EITHER
CASE, SHEAR AND INSTABILITY APPEAR SUFFICIENT FOR ISOLATED SEVERE
STORMS WITH LARGE HAIL THE PRIMARY THREAT GIVEN LESS FAVORABLE
DCAPE VALUES.
DISCUSSION
ISSUED AT 108 PM CDT WED AUG 26 2026
SURFACE HIGH PRESSURE REMAINS IN PLACE THROUGH THURSDAY RESULTING IN
QUIET WEATHER ACROSS THE AREA. LOWS IN THE 50S TONIGHT WITH HIGHS ON
THURSDAY IN THE LOWER TO MID 80S.
ELEVATED MOISTURE MOVES IN AROUND THE 700-800 MB LAYER LATE THURSDAY
NIGHT INTO FRIDAY MORNING. THIS COULD RESULT IN SPOTTY SHOWERS AND
ISOLATED THUNDERSTORMS. SHEAR IS WEAK AND CAPE VALUES RUNNING ABOUT
500-1000 J/KG. VERY DEPENDENT UPON THIS SMALL LAYER OF MOISTURE
HOWEVER, SO CONFIDENCE IS LOW FOR NOW.
SOUTHERLY FLOW BECOME ESTABLISHED AT THE SURFACE ON FRIDAY WITH
GUSTS AROUND 25 TO 30 MPH LIKELY. WITH SOUTH TO SOUTHEAST FLOW AT
THE SURFACE ANY INSTABILITY THAT DEVELOPS THROUGH THE DAY WILL
LIKELY REMAIN CAPPED, HOWEVER WITH SOME POTENTIAL FOR A WAVE TO MOVE
THROUGH ON FRIDAY AFTERNOON THIS CAPPING COULD WEAKEN AND ALLOW A
FEW THUNDERSTORMS TO DEVELOP. WITH MODERATE SHEAR AND 1000-1500
J/KG CAPE, AN ISOLATED SEVERE STORM WILL BE POSSIBLE. A SECONDARY
WAVE AND SLIGHTLY DEEPER INSTABILITY ON FRIDAY NIGHT MAY LEAD TO
ADDITIONAL SHOWER AND THUNDERSTORM CHANCES WITH ADDITIONAL SEVERE
WEATHER THREATS.
TEMPERATURES WARM ACROSS THE AREA ON SATURDAY AS THE WAVE MOVES BY
TO THE NORTH. EVEN WITH STRONGER WEST SOUTHWEST FLOW ALOFT AND
DECENT MID LEVEL WARM ADVECTION, WEAK MID TO UPPER LEVEL RIDGING
SHOULD SUPPRESS ANY CONVECTIVE ACTIVITY. HIGHS SHOULD CLIMB INTO THE
90S NEAR AND WEST OF I-90.
SUNDAY MAY BE A DAY TO KEEP AN EYE ON WE A WAVE TRACKS BY ALONG THE
CANADIAN BORDER AND A WEAKER SUB TROPICAL LIKE WAVE DRIFTS NORTHEAST
INTO THE AREA. WITH ANOTHER DAY EXPECTED TO CLIMB INTO THE 90S AND
SOME WEAK FORCING ALOFT, WE COULD SEE A FEW STORMS DEVELOP. FOR NOW
CONFIDENCE IS TOO LOW TO INCLUDE IN THE FORECAST.
SOUTHWEST FLOW ALOFT REMAINS IN PLACE THROUGH THE MIDDLE OF NEXT
WEEK AND THE NEXT WAVE OF INTEREST HAS SOME AGREEMENT AND MAY ARRIVE
MONDAY NIGHT INTO TUESDAY. OTHERWISE TEMPERATURES WILL REMAIN ABOVE
NORMAL MONDAY INT WEDNESDAY.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 1210 AM CDT THU AUG 27 2026
MAINLY VFR CONDITIONS WITH THE POTENTIAL FOR OCCASIONAL MVFR TO
IFR CONDITIONS WILL BE POSSIBLE THIS TAF PERIOD. TAKING A LOOK
AT SATELLITE IMAGERY, MOSTLY CLEAR CONDITIONS PERSIST TONIGHT.
THIS COMBINED WITH LIGHTER SURFACE WINDS COULD LEAD TO A FEW
PATCHY AREAS OF MVFR TO IFR FOG DEVELOPING MAINLY ALONG OUR
WATER WAYS AND A FEW LOWER SPOTS. WITH TEMPORARY REDUCTIONS IN
VSBYS POSSIBLE, DECIDED TO ADD A TEMPO GROUP TO KHON SINCE THATS
WHERE SOME GUIDANCE IS KEYING SO FAR. OTHERWISE, SHOULD SEE THE
LIGHT AND VARIABLE WINDS CONTINUE THROUGHOUT THE DAY.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...JH
DISCUSSION...08
AVIATION...05
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