238
FXUS63 KFSD 081733
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1233 PM CDT TUE SEP 8 2026
KEY MESSAGES
- ADDITIONAL SCATTERED THUNDERSTORMS ARE POSSIBLE THIS
AFTERNOON/EVENING. SEVERE RISK IS LOW AND FOCUSED SOUTHEAST OF
A SLOAN TO CHEROKEE LINE. THE MAIN THREATS REMAIN QUARTER
SIZED HAIL, WIND GUSTS TO 60 MPH, AND LOCALLY HEAVY RAIN.
- QUIET BUT CONTINUED WARM CONDITIONS ARE EXPECTED FOR THE REST
OF THE WORK WEEK WITH THE NEXT BETTER CHANCE FOR
PRECIPITATION SATURDAY NIGHT INTO SUNDAY.
UPDATE
ISSUED AT 219 AM CDT TUE SEP 8 2026
CONTINUING TO SEE STORMS MOVE ACROSS THE AREA THIS MORNING, AND
WATCHING THE DEVELOPMENT CONTINUE IN NE. HAVE SEEN STEADY DOWNWARD
TREND OVER LAST HOUR OR SO WITH SPORADIC GUSTS AROUND 50-55 MPH.
STORMS APPEAR TO BE ELEVATED AND TIED MORE TO THE LLJ FORCING NOW
THAN EARLIER TONIGHT. EXPECT PERIODS OF SHOWERS/STORMS TO CONTINUE
NEAR AND SOUTH OF I-90 THROUGH THE OVERNIGHT HOURS AS THE NEXT WAVE
LIFTS OUT OF NE AND THE LLJ REMAINS OVER THE AREA. ALTHOUGH STORM
MOTION IS MORE PROGRESSIVE, HIGH PWATS AND STILL RELATIVELY
DEEP WARM LAYER SUPPORT CONTINUED LOCALLY HEAVY RAIN. WILL NEED
TO WATCH AREAS THAT HAVE HAD MULTIPLE ROUNDS OF STORMS OVER THE
LAST FEW DAYS. TEMPERATURES THUS FAR ARE REMAINING MILD IN THE
UPPER 60S TO UPPER 70S THIS MORNING WITH WIND GUSTS AROUND 25-30
MPH AT TIMES. HIGHS WARM INTO THE 80S.
SHOWERS AND STORMS LINGER THROUGH THE DAY TUESDAY WITH THE SURFACE
COLD FRONT SAGGING SOUTH THROUGH THE DAY AND SOUTHWESTERLY FLOW
ALOFT PROMOTING WAVES THROUGH THE PATTERN. LOW END SEVERE RISK OUR
FAR SOUTHEASTERN FORECAST AREA (SOUTHEAST OF SLOAN TO CHEROKEE)
LATER THIS AFTERNOON AND EVENING. ANTICIPATE THAT WE'LL STRUGGLE
WITH DESTABILIZATION DUE TO MORNING CONVECTION AND CLOUD DEBRIS, SO
ANY SEVERE THREAT WOULD BE LIMITED TO A NARROW WINDOW THIS AFTERNOON
AND EVENING - LIKELY A COUPLE HOUR WINDOW BETWEEN 3 AND 8 PM
(DEPENDING ON IF/HOW QUICKLY WE DESTABILIZE AND WHERE THE SURFACE
BOUNDARY IS). SHEAR MAY TRAIL A BIT BEHIND ANY INSTABILITY INITIALLY
WHICH WOULD ALSO LIMIT THE SEVERE POTENTIAL. 60 MPH WIND GUSTS,
QUARTER SIZED HAIL, AND BRIEF HEAVY RAIN ARE THE MAIN THREATS.
STORMS SHOULD CLEAR OUT THROUGH THE EVENING HOURS, WITH A MORE
SEASONAL NIGHT TUESDAY NIGHT INTO WEDNESDAY.
DISCUSSION
ISSUED AT 103 PM CDT MON SEP 7 2026
ELEVATED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO MOVE
NORTHEAST THROUGH CENTRAL SD INTO THE AFTERNOON. LOCALLY HEAVY
RAIN AND WIND GUSTS TO 50 MPH WILL BE THE MAIN THREATS.
OTHERWISE, SHOWERS AND THUNDERSTORMS WILL LIKELY BE HARD TO
COME BY THIS AFTERNOON AS STRONG CAPPING IS IN PLACE. THE
EXCEPTION MAY BE IN CENTRAL SD CLOSER TO INCREASING SOUTHWEST
FLOW ALOFT AND SLIGHTLY STRONGER SURFACE HEATING. IF THESE
STORMS CAN DEVELOP, CAPE AROUND 2000 J/KG AS WELL AS ABOUT 40
KNOTS OF DEEP LAYER SHEAR AS WELL AS DECENT TURNING FROM
SOUTHEAST TO SOUTHWEST IN THE LOWEST KM. THIS WILL SUPPORT ALL
MODES OF SEVERE WEATHER WITH AN ISOLATED TORNADO, HAIL TO PING
PONG BALL AND WIND GUSTS TO 70 MPH. UNLESS THE MODELS ARE
COMPLETELY INCORRECT IN HANDLING THE CAPPING INVERSION, THE
CHANCE FOR THIS VERY LATE AFTERNOON AND EARLY EVENING CONVECTION
WILL BE CONFINED TO AREAS WEST OF THE JAMES RIVER. ONE OTHER
NEGATIVE IS THE ONGOING CONVECTION IN CENTRAL SD, WHICH APPEARS
TO BE TAKING A BITE OUT OF THE DAYTIME HEATING.
FARTHER EAST THE THREAT WILL BE MORE LIKELY FROM ABOUT 8 PM TO 2 AM
AS STORMS COULD BECOME MORE ROOTED IN A STRONGER LLJ WITH INCREASING
SOUTHWEST FLOW ALOFT. THIS LAY LEAD TO A CLUSTER OF STRONGER
UPDRAFTS WITH HALF DOLLAR SIZED HAIL, WIND GUSTS TO 60 MPH AND
POCKETS OF HEAVY RAIN THE MAIN THREATS.
INSTABILITY LINGERS THROUGH LATE TONIGHT INTO EARLY TUESDAY
MORNING AS UPPER LEVEL SUPPORT SLOWLY MOVES THROUGH. CONFIDENCE
IS LOW ON ADDITIONAL STRONGER CONVECTION, BUT WITH POTENTIALLY
1000-1500 J/KG OF INSTABILITY SOME ISOLATED STRONGER STORMS WILL
BE POSSIBLE. FOR NOW THE THREAT OF HEAVY RAIN LIKE THE PAST
COUPLE OF DAYS LOOKS PRETTY LOW AS STORMS SHOULD BE MORE
PROGRESSIVE.
INSTABILITY IS SLOW TO SHIFT SOUTHEAST THROUGH THE DAY ON TUESDAY
AND SHOULD RESULT IN ADDITIONAL SHOWERS AND POTENTIALLY STRONGER
THUNDERSTORMS TUESDAY AFTERNOON. THE BETTER CHANCE FOR THIS WILL
LIKELY BE SOUTH OF A YANKTON TO JACKSON MN LINE, WITH THE BETTER
CHANCE FROM ABOUT 3 PM TO 8 PM.
A STRONGER WESTERLY JET ALOFT SETTLES INTO THE AREA WEDNESDAY INTO
THURSDAY, WITH A FAST MOVING TROUGH EXPECTED TO MOVE THROUGH
THURSDAY NIGHT INTO FRIDAY. THIS PATTERN SHOULD SUPPORT DRY
CONDITIONS ON WEDNESDAY AND THURSDAY WITH A CHANCE FOR SHOWERS AND
THUNDERSTORMS LATE THURSDAY NIGHT, BUT MORE INTO FRIDAY. DEPENDING
UPON THE TIMING OF THE FRONT WITH THIS WAVE ON FRIDAY, HIGHS COULD
CLIMB INTO THE 90S IN A FEW LOCATIONS BEFORE A FAIRLY STRONG SHOT OF
COOLER AIR MOVES IN FOR NEXT WEEKEND WHERE HIGHS IN THE 70S ARE MORE
LIKELY. SATURDAY NIGHT INTO SUNDAY WILL SEE A DECENT CHANCE FOR
SHOWERS AND THUNDERSTORMS AS MODELS ARE FAIRLY AGREEABLE WITH A WAVE
MOVING THROUGH, JUST NOT SO MUCH WITH THE EXACT TIMING.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 1230 PM CDT TUE SEP 8 2026
A FRONT WILL DRIFT SOUTHEAST THROUGH THE AREA THIS AFTERNOON
INTO THE EVENING. SOME BRIEF MVFR CEILINGS WILL BE POSSIBLE NEAR
THIS FRONT. OTHERWISE SCATTERED SHOWERS AND THUNDERSTORMS WILL
MOVE THROUGH PARTS OF NORTHEAST NE AND NORTHWEST IA THROUGH
EARLY EVENING. AN ISOLATED STORM COULD BECOME SEVERE. OTHERWISE
MAINLY VFR CONDITIONS ARE EXPECTED. SOME PATCHY FOG IN NORTHWEST
IA WILL BE POSSIBLE LATE TONIGHT INTO WEDNESDAY MORNING.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...SG
DISCUSSION...08
AVIATION...08
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