433
FXUS63 KFSD 021733
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1233 PM CDT SUN AUG 2 2026
KEY MESSAGES
- WINDS INCREASE THROUGH THE DAY TODAY, REACHING 25-35 MPH ALONG
AND WEST OF I-29 THIS AFTERNOON. GUSTY WINDS GRADUALLY SPREAD
EAST THROUGH THE EVENING AND OVERNIGHT.
- DRY CONDITIONS AND SEASONABLY WARM TEMPERATURES CONTINUE TODAY
INTO MID-AFTERNOON MONDAY.
- SHOWER AND STORM CHANCES RETURN MONDAY NIGHT INTO WEDNESDAY.
AN ISOLATED STRONG TO SEVERE STORM IS POSSIBLE IN PORTIONS OF
SOUTHEAST SOUTH DAKOTA MONDAY EVENING, IF STORMS CAN DEVELOP.
UPDATE
ISSUED AT 430 AM CDT SUN AUG 2 2026
THOUGH NOT AS EVIDENT ON SATELLITE THIS MORNING, SURFACE OBS AND
WEBCAMS DO SUPPORT DEVELOPMENT OF PATCHY FOG, MAINLY CONFINED TO
RIVER VALLEYS FROM AROUND YANKTON ON THE MISSOURI RIVER INTO
NORTHWEST IOWA. FOG MAY BE LOCALLY DENSE WITH VISIBILITY 1/2
MILE OR LESS, BUT MOST AREAS SHOULD REMAIN ABOVE 1-3 MILES.
WITH INCREASING SOUTHEAST TO SOUTH WINDS TODAY, FEEL WE COULD
SEE ANOTHER DAY OF TEMPERATURES EXCEEDING NBM GUIDANCE AND HAVE
NUDGED HIGHS UP A FEW DEGREES, ESPECIALLY WEST OF I-29 WHERE
DEEPER MIXING WILL BE FAVORED. THAT SAID, STILL SEEING BROAD
COVERAGE OF SMOKE ALOFT, SO DID NOT PUSH HIGHS TOO FAR WITH
CONCERNS THAT SMOKE COULD LIMIT TEMPS FROM REACHING THEIR FULL
POTENTIAL. WITH THE SURFACE RIDGE LINGERING NEAR TO EAST OF
IA/MN HIGHWAY 60 INTO THIS AFTERNOON, THESE AREAS SHOULD SEE
LESS FAVORABLE MIXING, SO DID NOT DEVIATE FROM THE NBM IN OUR
EASTERN COUNTIES.
STILL LOOKING AT A CONDITIONAL SEVERE RISK MONDAY EVENING AS
THE COLD FRONT PUSHES IN, THOUGH STRENGTH OF A CAPPING INVERSION
REMAINS A CONCERN THAT COULD LIMIT STORM DEVELOPMENT. IF STORMS
CAN FORM AS DEPICTED BY A FEW OF THE CAMS, ISOLATED DAMAGING
WINDS WOULD BE THE MAIN THREAT. HAIL SIZE MAY BE LIMITED BY THE
WARM MID-LEVELS, THOUGH MARGINALLY SEVERE HAIL COULD OCCUR WITH
THE STRONGEST UPDRAFTS GIVEN STEEP MID-LEVEL LAPSE RATES. AGAIN,
THAT IS ALL CONTINGENT ON THE FRONT PROVIDING ENOUGH FORCING TO
BREAK THE CAP, AND AS SUCH, CONFIDENCE IN TIMING AND LOCATION OF
POTENTIAL STORMS IS LOW.
LITTLE CHANGE THROUGH THE MID-WEEK PERIOD, THOUGH TRENDS HAVE
SHIFTED LINGERING RAIN CHANCES SLIGHTLY SOUTH FOR WEDNESDAY WITH
LOW (20-30%) CHANCES FOCUSED ALONG THE HIGHWAY 20 CORRIDOR.
DISCUSSION
ISSUED AT 216 PM CDT SAT AUG 1 2026
HIGH PRESSURE CONTINUES TO PUSH THROUGH THE FORECAST AREA THIS
AFTERNOON. THIS HAS ALLOWED FOR HIGH TEMPERATURES TO WARM TO THE
UPPER 70S AND 80S WHILE WINDS REMAIN LIGHT. THESE PLEASANT
CONDITIONS WILL PERSIST FOR THE REST OF TODAY. WINDS WILL REMAIN
ELEVATED THROUGH THE NIGHT AS LOW LEVEL PRESSURE GRADIENTS TIGHTEN
AS THE SURFACE HIGH PRESSURE SYSTEM PASSES OFF TO THE SOUTHEAST.
SOME FOG IS POSSIBLE FOR LOCATIONS EAST OF I-29 TONIGHT WHERE THE
LIGHTEST WINDS WILL RESIDE.
SUNDAY WILL BE A SLIGHTLY WARMER DAY WITH HIGH TEMPERATURES WARMING
TO THE 80S TO LOW 90S. THE LOW LEVEL PRESSURE GRADIENTS WILL TIGHTEN
A BIT MORE FOR THE DAY, RESULTING IN SOUTHERLY GUSTS UP TO 20-35
MPH. THE STRONGEST GUSTS WILL OCCUR WEST OF I-29, AN ESPECIALLY WEST
OF THE JAMES RIVER. AFTER A BREEZY SUMMER DAY, AN INCOMING UPPER
LEVEL WAVE WILL RESULT IN A STRENGTHENING LOW LEVEL JET FOR THE
EVENING AND OVERNIGHT HOURS. THIS WILL KEEP WINDS ELEVATED THROUGH
THE NIGHT AND LOW TEMPERATURES ON THE LOW SIDE WITH LOWS ONLY
FALLING TO THE UPPER 50S AND 60S. A FEW LOCATIONS COULD SEE LOWS
BOTTOM OUT AROUND 70F.
THE NEXT CHANCE FOR SHOWERS AND THUNDERSTORMS LOOK TO RETURN TO THE
AREA ON MONDAY. SOME UNCERTAINTY REMAINS AS A COLD FRONT WILL BE
SITUATED WEST/NORTHWEST OF THE FORECAST AREA. STORMS COULD DEVELOP
ON THE FRONT DURING THE AFTERNOON AND EVENING TIMEFRAME BUT THIS
POTENTIAL IS UNCERTAIN AS A STOUT ELEVATED MIXED LAYER (EML) WILL BE
IN PLACE, CREATING A LARGE CAP. THE LATEST REFS SUPPORTS THIS AS IT
SHOWS A STRAIGHT 100% CHANCE FOR CONVECTIVE INHIBITION (CIN) VALUES
OF -100 J/KG OR LESS. HOWEVER, SOME OF THE LATEST MODELS SHOW THE
FRONT PUSHING THROUGH THE FORECAST AREA DURING THE OVERNIGHT HOURS,
WHICH COULD LEAD TO SOME CONVECTIVE DEVELOPMENT ALONG THE ELEVATED
PORTION OF THE FRONT. TOUGH TO SAY IF THIS POTENTIAL CONVECTION WILL
BE STRONG TO SEVERE AS EVEN THE ELEVATED PORTION OF THE FRONT MAY
RESIDE JUST AHEAD OF THE GREATER VERTICAL SHEAR. SOMETHING TO WATCH
OVER THE NEXT DAY OR TWO. OTHERWISE, MONDAY WILL BE NEAR TO ABOVE
SEASONABLE WITH HIGHS IN THE 80S TO LOW 90S.
THE ELEVATED FRONT WILL SLOWLY PUSH THROUGH THE REST OF THE FORECAST
AREA ON TUESDAY. WITH CONTINUED SHORTWAVES PASSING OVER THE ELEVATED
FRONT, RAIN LOOKS TO PERSIST ALONG THE FRONT FOR THE ENTIRETY OF
TUESDAY. THE ENSEMBLES SUPPORT THIS AS THEY SHOW A 30-70% CHANCE FOR
RAINFALL TOTALS TO EXCEED A TENTH OF AN INCH NEAR AND SOUTH OF I-90.
ANY APPRECIABLE INSTABILITY LOOKS TO RESIDE SOUTHEAST OF THE
FORECAST AREA, WHICH SHOULD KEEP SEVERE STORM CHANCES AT BAY. CAN'T
RULE OUT A STRAY RUMBLE OF THUNDER THOUGH. WIDESPREAD CLOUD COVER
AND RAIN WILL KEEP TEMPERATURES COOLER, DOWN TO THE 70S ACROSS THE
AREA.
SOME LIGHT RAIN COULD CONTINUE THROUGH WEDNESDAY BEFORE COMPLETELY
EXITING THE AREA. WEDNESDAY WILL SEE HIGHS BELOW AVERAGE AGAIN IN
THE 70S BEFORE HIGHS WARM BACK UP TO NEAR SEASONABLE IN THE 80S TO
LOW 90S ON THURSDAY, FRIDAY, AND SATURDAY. CHANCES FOR RAIN ARE
UNCERTAIN FOR THE END OF NEXT WEEK DUE TO THE INCREASING VARIANCE IN
THE UPPER LEVEL PATTERN. BUT IF LATEST TRENDS OF BROAD TROUGHING
OVER THE NORTHERN PLAINS HOLDS, THEN RAIN CHANCES COULD PERHAPS
INCREASE AS WE GET CLOSER TO THIS PERIOD OF TIME.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1232 PM CDT SUN AUG 2 2026
VFR CONDITIONS ARE EXPECTED FOR THE TAF PERIOD. LIGHT SOUTHEASTERLY
WINDS BEGIN THE TAF PERIOD. THE SOUTHEASTERLY WINDS WILL REMAIN
ELEVATED THROUGH THE OVERNIGHT HOURS AS THE LOW LEVEL JET (LLJ)
STRENGTHENS ALOFT. THIS WILL RESULT IN LOW LEVEL WIND SHEAR (LLWS)
FOR LOCATIONS ALONG AND WEST OF THE JAMES RIVER TONIGHT. THE LLWS
WILL COME TO AN END IN THE MORNING HOURS BUT BREEZY SOUTHERLY WINDS
WITH GUSTS UP TO 20-35 KNOTS WILL END THE PERIOD.
ISOLATED VALLEY FOG IS POSSIBLE TONIGHT MAINLY ACROSS PARTS OF
NORTHWEST IOWA WHERE WINDS ARE WEAKEST.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...JH
DISCUSSION...MEYERS
AVIATION...MEYERS
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