883
FXUS63 KFSD 140557
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1257 AM CDT MON SEP 14 2026
KEY MESSAGES
- SHOWERS AND THUNDERSTORMS DEVELOP AFTER 3AM MONDAY MORNING. A
LOW CHANCE FOR A MARGINALLY SEVERE STORM WITH HAIL COULD BE
POSSIBLE THROUGH 9AM AS ACTIVITY MOVES NORTHEAST.
- A VERY CONDITIONAL RISK FOR SEVERE STORMS FORMS LATE MONDAY
AFTERNOON ALONG HIGHWAY 20. ALL HAZARDS COULD BE POSSIBLE,
THOUGH CLOUD COVER MAY PLAY A SIGNIFICANT ROLE IN POTENTIAL.
- WE'LL REMAIN NEAR TO SLIGHTLY BELOW NORMAL FOR TEMPERATURES
DURING THE UPCOMING WEEK.
- SCATTERED NON-SEVERE RAIN CHANCES WILL FOCUS IN THREE
TIMEFRAMES, WITH THE HIGHEST PROBABILITIES OF RAINFALL FOCUSED
WEDNESDAY AND AGAIN LATE THURSDAY NIGHT AND FRIDAY.
UPDATE
ISSUED AT 951 PM CDT SUN SEP 13 2026
A COOL FALL LIKE EVENING CONTINUES ACROSS THE AREA, BUT MOISTURE
IS RETURNING FROM THE SOUTH AHEAD OF THE NEXT STORM SYSTEM TO
IMPACT THE AREA. SHOWERS WILL START TO MOVE INTO THE AREA FROM
THE WEST ESPECIALLY AFTER MIDNIGHT, WITH A BAND OF HEAVIER
SHOWERS AND ELEVATED THUNDERSTORMS LIKELY TO DEVELOP ALONG OR
JUST SOUTH OF THE MISSOURI RIVER VALLEY AFTER 3-4 AM, WITH THIS
BAND GRADUALLY LIFTING NORTH-NORTHEAST THROUGH THE SUNRISE
HOURS. STILL CAN'T RULE OUT A VERY ISOLATED INSTANCE OF
QUARTER-SIZED HAIL WHEN UPDRAFTS INITIALLY DEVELOP EARLY
TOMORROW MORNING, BUT FREEZING LEVELS AROUND 15,000 FT WILL
SIGNIFICANTLY HAMPER THE ABILITY FOR HAILSTONES THAT LARGE FROM
REACHING THE GROUND.
A SCREAMING LOW-LEVEL JET INTO THE DAYTIME HOURS WILL RESULT IN
ADDITIONAL DEVELOPMENT OF SHOWERS AND ISOLATED THUNDERSTORMS
THROUGH THE MORNING, SO BE PREPARED FOR SOME WET WEATHER AT
TIMES ON YOUR COMMUTE TO WORK OR SCHOOL! DUE TO THESE PERSISTENT
SHOWERS AND LINGERING CLOUD COVER, THE CHANCE FOR STRONG TO
SEVERE STORMS SURFACE-BASED STORMS TO DEVELOP MONDAY AFTERNOON
IN NORTHWEST IOWA CONTINUES TO REMAIN LOW AND HIGHLY
CONDITIONAL. CURRENT THINKING IS THE CAP SHOULD HOLD AND PREVENT
SURFACE-BASED CONVECTION FROM DEVELOPING, KEEPING THE TORNADO
THREAT SOUTH OF THE AREA. WILL CONTINUE TO MONITOR TRENDS
THROUGH THE NIGHT.
DISCUSSION
ISSUED AT 1240 PM CDT SUN SEP 13 2026
THIS AFTERNOON: ANOTHER COOL, BUT PLEASANT EARLY FALL DAY IN
THE REGION AS CONTINUED MID-LVL CLOUDS CROSS THE CWA. WITH A
LIGHT EAST SOUTHEAST WIND, WE'LL CONTINUE TO SEE TEMPERATURES
RISE TOWARDS THE UPPER 60S.
TONIGHT: TWO THIRDS OF THE OVERNIGHT HOURS ARE EXPECTED TO REMAIN
QUIET. HOWEVER AS WE MOVE PAST MIDNIGHT, A STEADY INCREASE IN A
BROAD LLJ THROUGH THE PLAINS, ALONG WITH THE APPROACH OF MID-LVL
VORTICITY WILL BEGIN TO DEVELOP SHOWERS AND THUNDERSTORMS. TWO
AREAS OF FOCUS FOR CONVECTION WILL DEVELOP THROUGH THE MORNING.
ONE AREA WILL BE ACROSS CENTRAL AND NORTH CENTRAL SOUTH DAKOTA,
WITH A SECOND BAND OF ELEVATED CONVECTION FORMING FROM SOUTH
CENTRAL SOUTH DAKOTA INTO EASTERN NEBRASKA WHERE STRONG THETA-E
ADVECTION BEGINS TO MOVE NORTHEAST. WHILE WIDESPREAD SEVERE
WEATHER ISN'T ANTICIPATED, SOUNDINGS SHOW ELEVATED CAPE AROUND
1500 J/KG THROUGH THE CWA. MID- LVL LAPSE RATES ARE MARGINAL,
BUT SHEAR COULD BE STRONG ENOUGH FOR A FEW STORMS BRIEFLY
CAPABLE OF QUARTER SIZE HAIL.
MONDAY: ONGOING CONVECTION AT DAYBREAK MONDAY WILL CONTINUE TO
MOVE NORTHEAST DURING THE MORNING HOURS. HREF/NBM MEAN QPF
SUGGESTS FAIRLY WIDESPREAD 0.25-0.50" TOTALS BY MID-DAY, BUT THE
CEILING IS ALSO QUITE HIGH WITH OUTSIDE POTENTIAL FOR AN INCH
OF RAIN IN VERY ISOLATED LOCATIONS. WHILE THE INITIAL BAND OF
MODERATE RAIN WILL MOVE AWAY FROM THE CWA BY EARLY AFTERNOON,
MODEL CONSENSUS KEEPS THE ORIENTATION OF THE LLJ FAVORABLE TO
ALLOW PERSISTENT SHOWERS OR EVEN ISOLATED THUNDERSTORMS WELL
INTO THE AFTERNOON. DEPENDING ON CLOUD COVER, A VERY NARROW
WINDOW FOR SURFACE BASED CONVECTION WILL STILL BE POSSIBLE BY
MID/LATE AFTERNOON AS A SURFACE WARM FRONT ATTEMPTS TO LIFT
NORTHWARD. WHILE MOST GUIDANCE HAS BACKED OFF ON THE NORTHWARD
EXTENT OF DESTABILIZATION AND KEPT THIS SOUTH OF HIGHWAY 20, A
FEW MODELS REMAIN STEADFAST THAT UPWARDS OF 2000+ J/KG MLCAPE
COULD DEVELOP FROM SIOUX CITY TO STORM LAKE BY 23Z. A QUICK
UPSCALE GROWTH SITUATION WOULD THEN DEVELOP AS LIFT IS MAXIMIZED
WITH AN APPROACHING MID-LVL VORT. IF STORMS COULD DEVELOP, ALL
HAZARDS WOULD BE POSSIBLE INITIALLY, WITH ACTIVITY RAPIDLY
SHIFTING SE EARLY IN THE EVENING.
THE PERSISTENT CLOUD COVER AND DEVELOPMENT OF WIDESPREAD LOW STRATUS
WILL LEAVE COOLER TEMPERATURES OVER THE CWA. I HAVE AGAIN ATTEMPTED
TO LOWER HIGHS TOWARDS THE COOLER SIDE OF NBM GUIDANCE. BARRING A
LATE AFTERNOON JUMP IF CLOUDS SCATTER, MOST LOCATIONS ESPECIALLY
EAST OF I-29 MAY STRUGGLE TO REACH 70 DEGREES AND THOSE IN SOUTHWEST
MINNESOTA COULD STILL BE TOO WARM WITH THEIR FORECAST HIGHS.
ONE FINAL ITEM OF NOTE FOR MONDAY WILL BE WINDS. A SHARPENING OF
THE SPG THROUGH THE MORNING WILL PROMOTE SUSTAINED WINDS AS HIGH AS
20 MPH AT TIMES. GUSTS, ESPECIALLY BEHIND DEPARTING RAIN, MAY RISE
INTO THE 30 TO 40 MPH RANGE INTO EARLY AFTERNOON.
TUESDAY-WEDNESDAY: HIGH PRESSURE ARRIVES FOR TUESDAY, SIGNALING DRY
CONDITIONS IN MOST LOCATIONS WITH CONTINUED SLIGHTLY COOLER THAN
NORMAL HIGH TEMPERATURES. A SLIGHT SHIFT OF MID-LVL FLOW BACK TO
THE SOUTHWEST BY WEDNESDAY COULD BRING ENOUGH MOISTURE RETURN FOR
SCATTERED SHOWERS IN MOST AREAS DURING THE DAY WEDNESDAY. THE FOCUS
OF THE STRONGEST MOISTURE RETURN, AND RESULTANT RISK FOR HEAVIER
PRECIPITATION CONTINUE TO STAY FOCUSED SOUTH OF HIGHWAY 20.
THURSDAY-SUNDAY: SHORTWAVE RIDGING MOVES BACK THROUGH THE PLAINS FOR
THURSDAY AND EARLY FRIDAY, SPELLING A RETURN OF DRY CONDITIONS AND
SOME POTENTIAL FOR TEMPERATURES TO RETURN TO NORMAL LEVELS TO
FINISH THE WEEK. AS ALLUDED TO IN YESTERDAY'S DISCUSSION,
SIGNALS REMAIN FAVORABLE FOR RAIN BY FRIDAY AS A STRONGER WAVE
EJECTS OUT OF THE SOUTHERN ROCKIES AND INTO THE PLAINS. STILL
LOTS OF DETAILS TO WORK OUT WITH THIS SYSTEM, BUT AS EXPECTED,
THE 24 HR PROBABILITIES FOR >0.25" ENDING SATURDAY MORNING HAVE
JUMPED OVER 50% IN ALL THREE MAJOR ENSEMBLES. QUITE A BIT OF
UNCERTAINTY FOR NEXT WEEKEND IN REGARDS TO THE EVENTUAL SHIFT
OF MID-LVL FLOW. ENSEMBLES SHOWING LOW PERCENTAGE POPS OVER A
LARGE AREA SUGGESTING A SIGNIFICANT SPREAD IN GUIDANCE. WHILE
SEVERE WEATHER RISKS ARE EXPECTED TO REMAIN LOW, TEMPERATURES
STAY NEAR SEASONAL NORMALS WITH AN 8 DEGREE SPREAD IN THE
25/75TH PERCENTILE DATA SPLIT EITHER SIDE OF NORMAL.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1255 AM CDT MON SEP 14 2026
SHOWERS AND STORMS WILL INCREASE IN COVERAGE HEADING TOWARDS
DAYBREAK TODAY, BRINGING MVFR CIGS AND VSBYS TO THE AREA.
BEHIND THE MAIN COMPLEX OF THIS MORNING'S ROUND OF STORMS, MVFR
TO IFR STRATUS WILL DEVELOP AND STICK AROUND THROUGH THE MID-
AFTERNOON. THE LOWEST CIGS WILL GENERALLY BE FOUND NEAR AND
NORTH OF I-90, THOUGH CONFIDENCE WAS NOT HIGH ENOUGH TO INCLUDE
IFR CONDITIONS AT KFSD NOR KHON AT THIS TIME. A FEW STRONGER
STORMS MAY DEVELOP OVER PRIMARILY NORTHWEST IOWA LATE THIS
AFTERNOON AND EARLY EVENING, THOUGH CONFIDENCE IN THIS
DEVELOPMENT WAS TOO LOW TO WARRANT MENTIONING AT KSUX.
SOUTHEASTERLY WINDS WILL CONTINUE TO INCREASE THROUGH THE REST OF
THE EARLY MORNING HOURS FOR THE ENTIRE AREA. STRONGEST GUSTS DURING
THE DAYTIME HOURS MONDAY WILL BE AROUND 30-35 KTS, WITH MOST OF THE
AREA FAIR GAME TO SEE GUSTS OCCASIONALLY UP TO THAT RANGE.
WINDS WILL DIMINISH HEADING THROUGH THE EVENING HOURS MONDAY. A
COLD FRONT MOVES INTO THE AREA FROM CENTRAL SOUTH DAKOTA AND
MOVES EAST THROUGH THE END OF THE PERIOD. THIS FRONT WILL TURN
WINDS TO THE WEST AND THEN NORTHWEST AS IT MOVES THROUGH.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...SAMET
DISCUSSION...DUX
AVIATION...SAMET
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page