537
FXUS63 KFSD 010139
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
839 PM CDT FRI JUL 31 2026
KEY MESSAGES
- GUSTY WINDS WILL BECOME LIGHT OVERNIGHT. THEY MAY EVEN BECOME
LIGHT ENOUGH FOR PATCHY FOG TO FORM NEAR WATER WAYS AND LOW
AREAS. PLEASE USE CAUTION ON YOUR MORNING COMMUTE.
- DRY CONDITIONS AND SEASONABLE TEMPERATURES RETURN FOR THE
WEEKEND. FOR NEXT WEEK, SHOWER AND STORMS CHANCES WILL RETURN
MONDAY NIGHT INTO TUESDAY.
UPDATE
ISSUED AT 837 PM CDT FRI JUL 31 2026
THE FORECAST REMAINS ON TRACK FOR THE NEXT 48 HOURS. SATURDAY EARLY
MORNING WINDS WILL BE LIGHT, BUT IT IS UNCERTAIN IF THEY WILL BECOME
LIGHT ENOUGH FOR FOG TO FORM. IF IT DOES, IT WILL BE PATCHY IN
NATURE AND MOST LIKELY CONFINED TO WATER WAYS AND LOW LAYING AREAS.
ANY FOG SHOULD BURN OFF BY MID-MORNING. NORTHERLY WINDS WILL
INCREASE AFTER SUNRISE AND BECOME SLIGHTLY BREEZY GUSTING TO 15-20
MPH. SKIES WILL BE MOSTLY FREE OF CLOUDS, HOWEVER A MILKY HAZE WILL
BE PRESENT DUE TO WILDFIRE SMOKE. HIGHS WILL BE ON THE LOW SIDE OF
AVERAGE IN THE MID 70S AND LOW 80S DUE IN PART TO WEAK CAA AND THE
SMOKE TO A LESSER EXTENT.
OVERNIGHT SUNDAY WINDS WILL BECOME LIGHT AND TURN TO THE SOUTH-
SOUTHEAST AS SURFACE HIGH PRESSURE PASSES THROUGH THE REGION FROM
NORTHWEST TO SOUTHEAST. SOUTHERLY WINDS USHER IN WARMER AND MOIST
AIR. DEW POINTS WILL CLIMB IN TO THE UPPER 60S TO LOW 70S. SLIGHTLY
WARMER HIGHS THANKS TO THE WAA WILL BE IN THE UPPER 70S TO MID 80S.
THE HIGHEST DEW POINTS AND WARMEST TEMPERATURES WILL BE OFFSET, AND
SO HEAT INDEX VALUES WILL BE NEAR TO SLIGHTLY WARMER THAN THE
FORECASTED HIGHS. SKIES WILL ONCE AGAIN BE MOSTLY CLEAR BUT OBSCURED
SOMEWHAT BY SMOKE. OVERNIGHT SUNDAY INTO MONDAY MORNING A SUBTLE
MID- LEVEL SHORT WAVE AND A STRENGTHENING LLJ MAY INDUCE
ISOLATED SHOWERS AND WEAK THUNDERSTORMS FOR AREAS ALONG AND
NORTH OF HIGHWAY 14. A VERY DRY SUBCLOUD LAYER WILL LIKELY
PREVENT MOST RAIN FROM REACHING THE GROUND, THEREFORE WE ARE NOT
EXPECTING MUCH IF ANY ACCUMULATION.
MONDAY'S HIGHS WILL BE SLIGHTLY WARMER IN THE LOW 80S TO LOW 90S
OVER SOUTH CENTRAL SOUTH DAKOTA. A COLD FRONT WILL MOVE THROUGH FROM
WEST TO EAST LATE MONDAY AFTERNOON INTO TUESDAY BRINGING THE NEXT
CHANCES FOR SHOWERS AND THUNDERSTORMS. AT THIS TIME STORMS DO NOT
LOOK TO BECOME SEVERE, HOWEVER THERE IS ALSO HIGH UNCERTAINTY. WE
WILL MONITOR THE TRENDS OVER THE NEXT DAYS. WHAT FOLLOWS FOR THE
REMAINDER OF THE WEEK LOOKS TO BE A SOMEWHAT ACTIVE PATTERN WITH
MULTIPLE CHANCES FOR SHOWERS AND THUNDERSTORMS.
DISCUSSION
ISSUED AT 247 PM CDT FRI JUL 31 2026
A NEARLY STACKED LOW PRESSURE SYSTEM WILL CONTINUE TO DRIFT
SOUTHEASTWARD INTO CENTRAL IOWA THROUGH THE REMAINDER OF THE
AFTERNOON, AND WITH THE SURFACE LOW DEEPENING, LOOK FOR WINDS TO
INCREASE A BIT MORE MAINLY EAST OF I-29 THROUGH THE EARLY EVENING
HOURS. MOST SPOTS TOP OUT WITH WIND GUSTS BETWEEN 35 AND 40
MPH, BUT ISOLATED POCKETS OF GUSTS TO AROUND 45 MPH WILL BE
POSSIBLE OVER NORTHWEST IOWA THROUGH ABOUT 7 TO 8 PM THIS
EVENING. THIS SHOULD REMAIN IN SHORT DURATION AND ISOLATED AND
SO DECIDED AGAINST WIND HEADLINES. MOISTURE ALSO CONTINUES TO
WRAP AROUND THIS LOW WHICH WILL KEEP MAINLY LIGHT RAIN IN THE
FORECAST THROUGH THIS EVENING PRIMARILY EAST OF I-29. SOUNDINGS
SHOW A LITTLE BIT OF ELEVATED INSTABILITY OVER PARTS OF
NORTHWEST IOWA, SO CAN'T RULE OUT A RUMBLE OF THUNDER THIS
AFTERNOON, BUT CHANCES FOR THIS ARE LOOKING LESS AND LESS
LIKELY. THE LAST OF THE SHOWERS SHOULD EXIT NORTHWEST IOWA BY 10
PM TO MIDNIGHT TONIGHT, LEADING TO DRY CONDITIONS HEADING INTO
THE WEEKEND.
PATCHY FOG IS POSSIBLE WHERE WINDS CAN GO VERY LIGHT TO CALM BY
EARLY TOMORROW MORNING, BUT IT DOES LOOK LIKE WINDS SHOULD REMAIN
ELEVATED ENOUGH TO PREVENT WIDESPREAD DEVELOPMENT. TRENDS WILL BE
MONITORED. OTHERWISE, A PLEASANT DAY IS IN STORE FOR TOMORROW
WITH HIGHS IN THE UPPER 70S TO LOWER 80S WITH DEW POINTS DOWN
INTO THE MID 50S WEST TO LOW 60S EAST. THESE LOWER DEW POINTS
WILL LEAD TO MORE COMFORTABLE CONDITIONS OUT THERE ESPECIALLY
WHEN COMPARED TO THE PAST FEW DAYS. THE HUMIDITY RELIEF WILL BE
SHORT-LIVED HOWEVER, AS SOUTHERLY FLOW RETURNS ON SUNDAY AND
ALLOWS DEW POINTS TO RISE THROUGH THE 60S AND POTENTIALLY AS
HIGH AS THE LOWER 70S IN THE AFTERNOON. IT WON'T BE NEARLY AS
HOT AS IT HAS BEEN THOUGH AS HIGHS WILL STILL REMAIN MAINLY IN
THE 80S WITH A FEW POCKETS OF HIGHS NEAR 90 IN SOUTH-CENTRAL
SOUTH DAKOTA. THOSE HOTTER AREAS WILL LIKELY BE OFFSET FROM THE
HIGHER DEW POINTS THOUGH, SO HEAT INDICES WON'T GET TOO HIGH.
TEMPERATURES WILL CONTINUE TO WARM ON MONDAY AND THIS WILL BE
OUT AHEAD OF OUR NEXT COLD FRONTAL PASSAGE. THIS COLD FRONT MAY
BRING A CHANCE OF STRONGER THUNDERSTORMS TO THE AREA, BUT THE
OVERNIGHT TIMING OF THE FRONTAL PASSAGE AND THE FACT THE BETTER
UPPER LEVEL SUPPORT WILL BE DISPLACED TO OUR NORTH LEADS TO A
LOW CONFIDENCE FORECAST FOR SEVERE WEATHER.
THIS FRONTAL BOUNDARY MAY STALL OUT OR SLOW DOWN NEAR OR SOUTH
OF THE HIGHWAY 20 CORRIDOR AS A LARGE UPPER WAVE PIVOTS SLOWLY
ACROSS THE REGION. THIS WILL KEEP RAIN AND STORM CHANCES IN THE
FORECAST MAINLY SOUTH OF I-90 THROUGH THE DAY ON TUESDAY AND
POTENTIALLY INTO WEDNESDAY AS WELL DEPENDING ON WHERE THE
FRONTAL BOUNDARY STALLS. WILL HAVE TO WATCH THIS FOR PERHAPS
SOME HEAVY RAIN POTENTIAL AS SOME OF THE LOWER RESOLUTION GLOBAL
MODELS SUCH AS THE 31.12Z ECMWF AND CANADIAN MODEL 48 HOUR QPF
ALREADY SHOWS A STRIPE OF 1 TO 3+ INCHES EITHER NEAR HIGHWAY 20
OR NEAR I-80 DEPENDING ON THE MODEL. SO WE'LL SEE WHAT THE
HIGHER RESOLUTION MODELS COME UP WITH AS WE GET CLOSER, BUT
THESE AREAS SOUTH OF I-90 DIDN'T RECEIVE AS MUCH RAIN WITH THIS
MOST RECENT SYSTEM, SO THE FLOOD THREAT MAY STILL REMAIN LOW
ANYWAY. COOLER WEATHER IMMEDIATELY FOLLOWS THE COLD FRONTAL
PASSAGE, WITH HIGHS LIKELY ONLY STAYING IN THE 70S TUESDAY AND
WEDNESDAY BEFORE GRADUALLY WARMING UP THROUGH THE END OF NEXT
WEEK.
AVIATION /00Z TAFS THROUGH 00Z SUNDAY/
ISSUED AT 622 PM CDT FRI JUL 31 2026
SCATTERED VFR AND MVFR CONDITIONS THIS AFTERNOON AS A LOW PRESSURE
SYSTEM SLOWLY MOVES OFF TO THE EAST. LOWER CEILINGS DUE TO CLOUD
COVER ARE PRESENT MOSTLY ALONG I-29 AND EAST. CEILINGS ARE EXPECTED
TO GRADUALLY IMPROVE THROUGH THE REST OF THIS EVENING, THEN REMAIN
VFR FOR THE DURATION.
WINDS ARE OUT OF THE NORTH AND GUSTING 20-30 KTS. THESE WILL ALSO
GRADUALLY DISSIPATE AS THE LOW MOVES OUT THIS EVENING. WINDS WILL
BECOME LIGHTER OVERNIGHT. SOME PATCHY FOG MAY FORM IF WINDS FALL TO
LIGHT AND VARIABLE, BUT CONFIDENCE IN BOTH FOG AND LOW WINDS IS LOW.
STILL, LOW LAYING AREAS AND WATER WAYS MAY STILL SEE PATCHY FOG BY
SATURDAY MORNING THAT SHOULD BURN OFF SHORTLY AFTER SUNRISE.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...AJP
DISCUSSION...SAMET
AVIATION...AJP
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