599
FXUS63 KFSD 291947
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
247 PM CDT WED JUL 29 2026
KEY MESSAGES
- FOR TODAY, HEAT INDICES WILL CONTINUE TO BE NEAR 100 DEGREES
THROUGH THIS AFTERNOON MAINLY WEST OF I-29, SO CONTINUE TO
STAY HYDRATED OUT THERE! ALSO, A POP-UP SHOWER OR STORM IS
POSSIBLE NEAR AND SOUTH OF THE MISSOURI RIVER VALLEY THIS
AFTERNOON, BUT SEVERE WEATHER IS NOT EXPECTED.
- CHANCES FOR SHOWERS AND STORMS INCREASE THURSDAY MORNING,
CONTINUING THURSDAY NIGHT INTO EARLY FRIDAY. SOME STORMS MAY
BE STRONG TO SEVERE LATE THURSDAY INTO THURSDAY NIGHT WITH
STRONG WIND GUSTS TO 65 MPH AND HEAVY RAIN THE MAIN THREATS.
- OVERALL BENEFICIAL RAINFALL IS EXPECTED THURSDAY THROUGH
FRIDAY MORNING, WITH A 60-90% PROBABILITY OF AT LEAST 0.50
INCHES AND A 30-70% CHANCE OF AT LEAST AN INCH FOR THE AREA.
THIS RAINFALL COULD HOWEVER LEAD TO ISOLATED FLASH FLOODING IN
URBAN AND FLOOD PRONE AREAS, SO BE SURE TO REMAIN WEATHER
AWARE.
DISCUSSION
ISSUED AT 241 PM CDT WED JUL 29 2026
LINES OF CUMULUS CLOUDS HAVE DEVELOPED NEAR AND SOUTH OF THE
MISSOURI RIVER VALLEY THIS AFTERNOON. WITHOUT MUCH UPPER LEVEL
SUPPORT TO GET STORMS GOING, WE WILL NEED TO RELY ON SPOTS
REACHING CONVECTIVE TEMPERATURES TO GET STORMS TO INITIATE.
ACCORDING TO SOUNDINGS, THIS WILL BE AROUND 95 DEGREES OR SO.
CHANCES FOR STORM DEVELOPMENT WITH THIS IS LOW, BUT EITHER WAY
SEVERE WEATHER IS UNLIKELY GIVEN WEAK MID LEVEL LAPSE RATES AND
WEAK SHEAR. HOWEVER, CAN'T RULE OUT A WIND GUST UP TO 55 MPH IN
ANY COLLAPSING THUNDERSTORM IF THEY EVEN DEVELOP IN OUR AREA IN
THE FIRST PLACE. OTHERWISE ANOTHER VERY WARM AND HUMID
AFTERNOON CONTINUES, WITH HEAT INDICES PUSHING 100 DEGREES AT
TIMES ESPECIALLY WEST OF I-29 INTO THE SIOUX CITY METRO.
DOESN'T LOOK LIKE THESE 100 DEGREE HEAT INDICES WILL BE TOO
WIDESPREAD AND DEW POINTS DO LOOK TO DROP OFF A BIT MORE THROUGH
THE AFTERNOON, SO DID CONTINUE TO HOLD OFF ON ANY HEAT
HEADLINES. HOWEVER, IT'S STILL IMPORTANT TO BE HYDRATED AND TAKE
SOME BREAKS WHEN WORKING OR PLAYING OUTDOORS THIS AFTERNOON!
SHOWERS AND STORMS OVER WESTERN SOUTH DAKOTA WILL BE KNOCKING ON
SOUTH-CENTRAL SOUTH DAKOTA'S DOOR BY DAYBREAK THURSDAY;
HOWEVER, THIS ACTIVITY WILL LIKELY BE WEAKENING AS IT MOVES INTO
THE AREA. ADDITIONAL SHOWERS AND STORMS WILL LIKELY DEVELOP AS
AN UPPER LEVEL WAVE MOVES ACROSS THE AREA AND WILL LIKELY HAVE
ENOUGH WITH IT TO BREAK THE CAP IN THE FAIRLY WEAKLY CAPPED
ENVIRONMENT. THIS MORNING ACTIVITY IS UNLIKELY TO BE SEVERE AND
SHOULD HELP LIMIT FULL DESTABILIZATION FROM OCCURRING BEFORE
ANY AFTERNOON/EVENING ACTIVITY DEVELOPS. HOWEVER, WE WILL STILL
LIKELY SEE A LINE OF STRONGER THUNDERSTORMS DEVELOP IN THE
AFTERNOON OVER CENTRAL SOUTH DAKOTA AND MOVE SOUTHEASTWARD
ACROSS THE AREA THROUGH THE EVENING HOURS ASSOCIATED WITH A COOL
FRONT. 65 MPH WINDS AND QUARTER SIZED HAIL WILL BE THE MAIN
THREAT WITH THIS AFTERNOON/EVENING ACTIVITY.
THERE IS AN ALTERNATE, BUT LESS LIKELY SCENARIO WHERE WE DON'T
GET MUCH IF ANY RAINFALL DURING THE THURSDAY MORNING TIME FRAME
DUE TO A STRONGER THAN EXPECTED CAP, ALLOWING FOR MORE
DESTABILIZATION TO OCCUR. IN THIS SCENARIO, LIKE SHOWN IN THE
29.12Z HRRR, A STRONGER LINE/MCS WOULD DEVELOP IN THE AFTERNOON
AND EVENING AND BRING WIND GUSTS POTENTIALLY UP TO AROUND 75
MPH. TRENDS WILL BE MONITORED, SO KEEP UP TO DATE WITH THE
LATEST FORECAST. A SECONDARY WAVE AND AN UPPER LEVEL LOW WILL
CLOSE OFF NEAR THE AREA THURSDAY NIGHT INTO EARLY FRIDAY MORNING,
LIKELY KEEPING GENERAL SHOWERS AND THUNDERSTORMS CONTINUING
INTO THE NIGHT. THIS WILL ALSO LEAD TO SOME FLASH FLOODING
CONCERNS THURSDAY AFTERNOON INTO THE NIGHT. WET GROUNDS FROM
MORNING SHOWERS/STORMS WILL COMBINE WITH THE STRONGER AFTERNOON
STORMS AND OVERNIGHT STORMS TO LEAD TO SOME FLASH FLOODING
CONCERNS MAINLY IN URBAN AREAS THAT SEE MULTIPLE THUNDERSTORMS.
RAINFALL TOTALS THROUGH THURSDAY NIGHT/EARLY FRIDAY MORNING WILL
BE AROUND A HALF AN INCH TO 1.5", BUT LOCALIZED AMOUNTS
EXCEEDING 4+ INCHES WILL BE POSSIBLE. MAKE SURE TO STAY WEATHER
AWARE AND KEEP UP TO DATE WITH THE LATEST FORECAST!
AFTER THIS NEXT STORM SYSTEM PASSES, AN UPPER LEVEL RIDGE WILL BUILD
INTO THE AREA AND HELP TO KEEP US DRY. AND WITH NORTHERLY FLOW IN
PLACE, HIGH TEMPERATURES FOR FRIDAY AND SATURDAY WILL BE A LOT MORE
PLEASANT WITH SOME AREAS ESPECIALLY ON FRIDAY HAVING HIGHS STAYING
ONLY IN THE 70S! SOUTHERLY FLOW RETURNS AGAIN BY SUNDAY, SO WE
SHOULD START TO SEE ANOTHER WARM UP, THOUGH WE SHOULD STAY BELOW
HEAT ADVISORY CRITERIA EVEN AS HIGHS WARM BACK UP TO THE MIDDLE 80S
TO LOWER 90S. THE NEXT APPRECIABLE RAIN CHANCES WILL RETURN MONDAY
NIGHT INTO TUESDAY AS COLD FRONT MOVES INTO THE AREA. IT LOOKS LIKE
THERE MAY BE ENOUGH INSTABILITY AND SHEAR FOR AT LEAST SOME SEVERE
THREAT, BUT UNCERTAINTY REMAINS HIGH AT THIS TIME.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1244 PM CDT WED JUL 29 2026
CAN'T RULE OUT A POP-UP SHOWER OR THUNDERSTORM THIS AFTERNOON
AND EARLY EVENING ALONG AND SOUTH OF A KSUX TO K9V9 LINE; HOWEVER,
CHANCES FOR THIS ARE QUITE LOW, GENERALLY LESS THAN 20%. OTHERWISE,
ADDITIONAL SHOWERS AND STORMS CAN BE EXPECTED HEADING INTO THE DAY
TOMORROW. LOWER CONFIDENCE IN COVERAGE OF MORNING THUNDERSTORM
ACTIVITY THURSDAY PRECLUDES MENTION OF TSRA IN THE TAFS AT THIS
TIME, AS THE BETTER CHANCES APPEAR TO BE AFTER THE CURRENT FORECAST
PERIOD.
WINDS WILL BE MAINLY OUT OF THE SOUTHEAST THROUGH THE PERIOD,
GUSTING TO AROUND 20 KTS AT TIMES THIS AFTERNOON NEAR AND WEST OF
THE JAMES RIVER AND AGAIN DURING THE DAYTIME THURSDAY ACROSS THE
AREA.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...SAMET
AVIATION...SAMET
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