486
FXUS63 KFSD 300210
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
910 PM CDT WED JUL 29 2026
KEY MESSAGES
- 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.
- DRY CONDITIONS AND SEASONABLE TEMPERATURES RETURN FOR THE
WEEKEND.
UPDATE
ISSUED AT 908 PM CDT WED JUL 29 2026
THUNDERSTORMS HAVE DEVELOPED ACROSS THE WESTERN PART OF THE STATE
THIS EVENING. THESE STORMS WILL PUSH EASTWARDS THROUGH THE REST OF
THE EVENING AND OVERNIGHT HOURS. THE STORMS WILL BE MOVING INTO AN
INCREASINGLY STABLE AIRMASS CHARACTERIZED BY DRY AIR IN THE MID
LEVELS WHICH WILL RESULT IN WEAKENING THE STORMS. THUS, NO SEVERE
STORMS ARE EXPECTED BUT A WEAK STORM TO SHOWER IS POSSIBLE AROUND
AND JUST AFTER DAYBREAK TOMORROW MORNING IN LOCATIONS WEST OF THE
JAMES RIVER.
DEPENDING ON HOW LONG THE CLOUD DEBRIS LASTS FROM THESE MORNING
SHOWERS ON THURSDAY, IT COULD KEEP HIGH TEMPERATURES A BIT COOLER IF
THESE CLOUDS STICK AROUND LONG ENOUGH. THERE IS ALSO A SIGN FROM
SOME OF THE MODELS THAT LOW LEVEL STRATUS COULD DEVELOP ACROSS PARTS
OF NEBRASKA AND PUSH INTO THE AREA TOMORROW MORNING AS WELL.
HOWEVER, THE MODELS ARE SOMEWHAT CONSISTENT IN SHOWING CLEARING
SKIES OR AT LEAST BREAKS IN THE CLOUD COVER WEST OF I-29 TO ALLOW
FOR SUFFICIENT DESTABILIZATION TO TAKE PLACE. SHOULD THIS HAPPEN,
HIGH TEMPERATURES WILL WARM TO THE 80S ACROSS THE AREA WITH MOIST
DEW POINTS IN THE UPPER 60S AND 70S. WITH MOIST NEUTRAL LAPSE RATES
IN PLACE, NO CAPPING WILL BE PRESENT. AS SUFFICIENT SURFACE HEATING
IS REACHED, A MID LEVEL WAVE WILL BE PUSHING INTO THE AREA, ALLOWING
FOR POTENTIALLY MORE WIDESPREAD CONVECTION TO DEVELOP ALONG AN
INVERTED TROUGH/WEAK SURFACE LOW. WITH THE MID LEVEL LOW OVER THE
FORECAST AREA, VERTICAL SHEAR VALUES WILL BE MITIGATED. AS OF NOW,
ONLY, LOOKING AT DEEP LAYER SHEAR VALUES ON THE ORDER OF ABOUT 25 TO
30 KNOTS. STILL SUFFICIENT ENOUGH TO ALLOW SOME STORMS TO BECOME
STRONG TO SEVERE WITH DAMAGING WINDS TO 65 MPH VIA WATER LOADED
DOWNDRAFTS. SOME BETTER STORM ORGANIZATION IS POSSIBLE AS MOST OF
THE HI-RES MODELS HAVE STORMS GROWING INTO A LINE DURING THE EARLY
EVENING HOURS. THIS LINE MAY HAVE THE BEST POTENTIAL FOR DAMAGING
WINDS. HEAVY RAINFALL REMAINS ON THE TABLE AS WELL AS PRECIPITABLE
WATER (PWAT) VALUES REMAIN IN THE 99TH PERCENTILE OF CLIMATOLOGY.
THUS FLASH FLOODING IS POSSIBLE WITH THESE STORMS. ESPECIALLY IF
THEY TRAIN OVER AN INDIVIDUAL LOCATION OR PASS THROUGH URBAN AREAS.
WHILE THE GREATEST CHANCE FOR FLASH FLOODING AND STRONG TO SEVERE
STORMS WILL BE WANING HEADING INTO THE OVERNIGHT HOURS, COULD STILL
SEE WEAKER STORMS PERSIST THROUGH THE OVERNIGHT TIMEFRAME. LATEST
GUIDANCE IS SHOWING A POTENTIAL WRAP AROUND/TROWAL LIKE
PRECIPITATION SHIELD TO DEVELOP ON FRIDAY AND PERSIST ACROSS
LOCATIONS MAINLY ALONG AND EAST OF I-29 THROUGH THE DAY ON FRIDAY
BEFORE EXITING THE AREA FRIDAY EVENING. ALL THIS TO SAY THAT
RAINFALL AMOUNTS REMAIN ON TRACK BETWEEN A HALF AN INCH TO UP TO
ABOUT AN INCH AND A HALF ACROSS THE ENTIRE AREA. LOCALLY HIGHER
AMOUNTS UP TO AND EXCEEDING 4 INCHES REMAINS POSSIBLE IN THE
HEAVIEST STORMS AS WELL. ALTHOUGH DROUGHT CONDITIONS PERSIST ACROSS
THE AREA, THIS HEAVIER RAINFALL CAN STILL CAUSE FLASH FLOODING
CONCERNS SO CONTINUE TO MONITOR THE LATEST FORECAST FOR THE MOST UP
TO DATE INFORMATION.
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 65
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 /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 625 PM CDT WED JUL 29 2026
LATEST SATELLITE SHOWS A DIURNALLY DRIVEN CU FIELD ACROSS THE
MISSOURI RIVER VALLEY EARLY THIS EVENING. AM NOT EXPECTING ANY NEW
THUNDERSTORM DEVELOPMENT IN THIS AREA SO SHOULD SEE THE CU FIELD
DISSIPATE OVER THE NEXT FEW HOURS. THUNDERSTORMS ACROSS THE WESTERN
PART OF THE STATE WILL SLOWLY PUSH EASTWARDS THROUGH THE EVENING AND
OVERNIGHT HOURS WHILE ON A WEAKENING TREND. THERE REMAINS
UNCERTAINTY AS TO WHETHER OR NOT THEY WILL SURVIVE ALL THE WAY TO
THE AREA SO HAVE LEFT OUT ANY CHANCE FOR RAIN IN ALL TAFS. A FEW
MODELS SUGGEST THAT LOW LEVEL STRATUS COULD DEVELOP ACROSS TOMORROW
MORNING. HOWEVER, THIS HAS A LOW PROBABILITY (~20%) OF OCCURRING SO
HAVE ALSO LEFT OUT OF ALL TAFS. WILL MONITOR TRENDS THROUGH THE REST
OF THE EVENING AND OVERNIGHT HOURS.
ANOTHER ROUND OF SHOWERS AND STORMS IS EXPECTED TOMORROW AFTERNOON.
STORMS LOOK TO DEVELOP WEST OF I-29 DURING THE AFTERNOON TIMEFRAME.
THESE STORMS WILL BE PUSHING EASTWARDS TO END THE PERIOD.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...MEYERS
DISCUSSION...SAMET
AVIATION...MEYERS
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