617
FXUS63 KFSD 080527
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1227 AM CDT TUE SEP 8 2026
KEY MESSAGES
- A LINE OF STORMS CONTINUES TO MOVE EAST JUST NORTH OF THE
MISSOURI VALLEY LATE THIS EVENING. WIND GUSTS TO 65 MPH AND
QUARTER SIZED HAIL ARE POSSIBLE. TORNADO RISK IS LOW BUT NOT
ZERO. LOCALLY HEAVY RAIN AND ISOLATED FLASH FLOODING ARE ALSO
A CONCERN.
- ADDITIONAL SCATTERED AND POSSIBLY SEVERE STORMS ARE POSSIBLE
INTO THE OVERNIGHT HOURS AND AGAIN TUESDAY AFTERNOON/EVENING.
THE MAIN THREATS REMAIN QUARTER SIZED HAIL, WIND GUSTS TO 65
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 1040 PM CDT MON SEP 7 2026
A FEW STORMS, SOME STRONG TO SEVERE, HAVE BEEN MOVING ALONG THE MO
RIVER THIS EVENING. ALTHOUGH GENERALLY TRENDING DOWNWARD, STILL MAY
SEE SOME WIND GUSTS TO 65 MPH AND QUARTER SIZED HAIL AS STORMS ARE
BEGINNING TO SHOW MORE LINEAR CHARACTERISTICS OVER THE LAST 30
MINUTES WITH SHEAR PERPENDICULAR TO THE STORMS. TORNADO RISK IS LOW.
MAIN THREATS MAY BE SHIFTING TO WIND AND LOCALLY HEAVY RAIN/ISOLATED
FLOODING ISSUES AS THE STORMS TRAIN OVER THE SAME AREAS NEAR THE 700
MB CONVERGENCE, THE 850 MB BOUNDARY, AND THE LLJ. STORM MOTION
GENERALLY WILL BE EAST TO NORTHEAST.
NEXT AREA TO WATCH IS WITH THE NEXT WAVE OUT OF NE THROUGH THE
OVERNIGHT HOURS. GUIDANCE SHOWS ADDITIONAL CONVECTIVE DEVELOPMENT
WITH SOME WEAK TO MODERATE INSTABILITY. LLJ ALSO MAY AID IN KEEPING
STORMS AROUND THROUGH THE OVERNIGHT HOURS. CONFIDENCE IS LOW IN THE
SEVERE POTENTIAL GIVEN THE DECREASING SHEAR AND INSTABILITY THROUGH
THE OVERNIGHT HOURS INTO EARLY TUESDAY.
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 /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 1215 AM CDT TUE SEP 8 2026
MAIN AVIATION CONCERN THROUGH TUESDAY NIGHT WILL BE PERIODS OF
SHOWERS AND STORMS. ONE ROUND OF SHOWERS/STORMS IS MOVING SLOWLY
TO THE EAST-NORTHEAST AT THE TIME OF THIS DISCUSSION NEAR THE
I-90 CORRIDOR AND OCCASIONALLY PRODUCING WIND GUSTS AROUND 45
KNOTS. ALSO SEEING SOME LOCALLY HEAVY RAINFALL AS WELL. SOME
PATCHY MVFR AND LOWER CONDITIONS HAVE BEEN OBSERVED WITH THESE
STORMS.
NEXT AREA TO WATCH IS ACROSS NE, AND WILL MOVE INTO THE AREA
LATER IN THE OVERNIGHT HOURS INTO TUESDAY MORNING - THESE MAY BE
REMAIN SOUTH OF I-90. ANOTHER CHANCE FOR CONVECTION RETURNS TO
NORTHWESTERN IA AND ADJACENT PORTIONS OF NORTHERN NE/FAR
SOUTHEASTERN SD DURING THE AFTERNOON AND EVENING. AN ISOLATED
STRONGER STORM MAY BE POSSIBLE. CONVECTION MAY LEAD TO MVFR AND
LOWER CONDITIONS.
OUTSIDE OF CONVECTION, EXPECT SHIFTING WIND DIRECTION THROUGH
THE PERIOD WITH A COUPLE OF BOUNDARIES IN PLACE. SYNOPTIC NON-
THUNDERSTORM WINDS AT TIMES GUST AROUND 20-25 KNOTS. LIGHT WINDS
TO END THE PERIOD. VFR CONDITIONS PREVAIL BARRING CONVECTION.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...SG
DISCUSSION...08
AVIATION...SG
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