836
FXUS63 KFSD 130221
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
921 PM CDT SUN APR 12 2026
KEY MESSAGES
- STRONG TO SEVERE STORMS ARE POSSIBLE TOMORROW. SOME
UNCERTAINTY REMAINS BUT LOCATIONS ALONG AND NEAR HIGHWAY-14
FROM BROOKINGS, SOUTH DAKOTA TO MARSHALL, MINNESOTA HAVE THE
HIGHEST CHANCES FOR SEEING STRONG TO SEVERE STORMS. THE MAIN
TIMEFRAME FOR SEVERE WEATHER IS BETWEEN 3 PM TO 9 PM MONDAY.
CONTINUE TO CHECK THE FORECAST FOR THE MOST UP TO DATE
INFORMATION.
- CHANCES (20-60%) FOR SHOWERS AND STORMS LOOK TO PERSIST
THROUGH THE REST OF THE WEEK. DETAILS REMAIN UNCERTAIN AT THIS
TIME.
UPDATE
ISSUED AT 921 PM CDT SUN APR 12 2026
WINDS HAVE BECOME LIGHT AND VARIABLE THIS EVENING. THERE IS A LOW TO
MODERATE PROBABILITY (30-40%) FOR PATCHY FOG DEVELOPMENT OVER
NORTHWEST IOWA EARLY MONDAY MORNING. BRIEF REDUCTIONS IN VISIBILITY
ARE POSSIBLE DOWN TO AROUND 2 MILES. PLEASE BE PREPARED FOR CHANGING
CONDITIONS AS YOU MAKE YOUR MORNING COMMUTE. FOG IS EXPECTED TO BURN
OFF BY MID-MORNING.
MONDAY CHANCES FOR SHOWERS AND THUNDERSTORMS RETURN TO THE FORECAST
AREA. HIGH TEMPERATURES WILL CLIMB INTO THE UPPER 70S TO MID 80S. AT
THE SAME TIME A PLUME OF MOISTURE WILL POOL TO THE EAST OF DRYLINE
THAT STRETCHES SOUTH FROM A SURFACE LOW PRESSURE LOCATED ON THE
BORDERS OF CENTRAL SOUTH DAKOTA AND NEBRASKA. THIS MOISTURE
ADVECTION AIDS IN DESTABILIZATION OF THE WARM SECTOR AS THE LOW
GRADUALLY MOVES NORTHEAST THROUGH THE DAY. OVERALL DYNAMIC
PARAMETERS ARE FAVORABLE FOR ISOLATED TO SCATTERED STRONG TO SEVERE
THUNDERSTORMS TO DEVELOP MONDAY AFTERNOON. HOWEVER, A VERY STRONG
CAP WILL BE IN PLACE THROUGH MUCH OF THE DAY. MIXING WILL WORK TO
WEAKEN THE CAP BUT WILL IT BE ENOUGH THAT A SURFACE BASED PARCEL CAN
BREAK THROUGH? THAT IS THE MAIN QUESTION AND WILL HAVE THE MOST
IMPACT ON STORM EVOLUTION AND THREATS. THE MOST LIKELY SCENARIO IS
ELEVATED THUNDERSTORMS BEGIN TO FIRE IN THE AFTERNOON IN EAST
CENTRAL SOUTH DAKOTA AND SOUTHWESTERN MINNESOTA AS THE SOUTHWEST TO
NORTHEAST ORIENTED LLJ BEGINS TO RAMP UP ALONG AND EAST OF I-29. THE
PRIMARY THREAT WITH THESE WOULD BE LARGE HAIL UP TO 2 INCHES IN
DIAMETER, AND DAMAGING WIND GUSTS OF 70 MPH. THESE STORMS
QUICKLY MOVE NORTHEAST OF THE FORECAST AREA. A SECOND ROUND OF
STORMS MAY BE POSSIBLE AS A SECONDARY WEST TO EAST ORIENTED LLJ
FORMS OVER CENTRAL SOUTH DAKOTA. AS THE JET INTERACTS WITH THE
TRIPLE POINT, AN ISOLATED SUPERCELL OR TWO IS POSSIBLE. SHOULD
THESE DEVELOP NOT ONLY IS LARGE HAIL AND DAMAGING WIND A THREAT,
BUT A TORNADO OR TWO CANNOT BE RULED OUT. THE AREA MOST LIKELY
TO SEE THIS SECOND ROUND IS ALONG HIGHWAY 14 FROM ROUGHLY
CENTRAL SOUTH DAKOTA EAST INTO SOUTHWEST MINNESOTA. AS 00Z DATA
HAS BEGUN TO FLOW IN SOME OF THE CAMS GUIDANCE HAS BEGUN TO PICK
UP ON THIS DEVELOPMENT.
DISCUSSION
ISSUED AT 243 PM CDT SUN APR 12 2026
FIRE DANGER PERSISTS THIS AFTERNOON ALONG AND WEST OF I-29. MORE
DETAILS CAN BE FOUND IN THE FIRE WEATHER DISCUSSION BELOW. BREEZY
WESTERLY WINDS PERSIST WITH HIGH TEMPERATURES WARMING TO THE 70S TO
LOW 80S, MAKING FOR A WARM APRIL DAY. FIRE DANGER WILL COME TO AN
END THIS EVENING AS TEMPERATURES COOL AND WINDS WEAKEN. LOW
TEMPERATURES WILL FALL TO THE UPPER 40S AND 50S OVERNIGHT.
WINDS WILL TURN TO OUT OF THE SOUTH/SOUTHEAST ON MONDAY, RESULTING
IN MOIST SOUTHERLY FLOW AND MOISTENING DEW POINTS BACK INTO THE 40S,
50S, AND EVEN LOW 60S. HIGH TEMPERATURES WILL WARM TO THE UPPER 70S
AND 80S ACROSS THE AREA AS A WARM FRONT PUSHES NORTHWARDS. THERE
REMAINS UNCERTAINTY IN WHERE THE WARM FRONT SETS UP. SOME OF THE
LATEST HI-RES MODELS BRING THE WARM FRONT TO THE VICINITY OF HIGHWAY-
14. SOME PUSH THE FRONT JUST NORTH OF THE HIGHWAY WHILE OTHERS ARE
JUST SOUTH. THIS WILL HAVE A BIG EFFECT ON ANY SEVERE STORM
POTENTIAL DURING THE AFTERNOON HOURS TOMORROW. A STOUT ELEVATED
MIXED LAYER (EML) WILL BE IN PLACE. SOUNDING CLIMATOLOGY WOULD PLACE
THIS EML AT THE VERY TOP OF CLIMATOLOGY FOR THIS TIME OF YEAR! THIS
EML WILL RESULT IN CAPPING ACROSS THE WARM SECTOR, LIMITING MORE
WIDESPREAD CONVECTIVE COVERAGE. IT COULD COMPLETELY PROHIBIT ANY
STORMS FROM DEVELOPING ACROSS THE AREA THOUGH AGAIN THAT DEPENDS ON
WHERE THE WARM FRONT SETS UP. THIS UNCERTAINTY ALSO EXTENDS TO THE
LOCATION OF THE SURFACE LOW TIED TO THE WARM FRONT. LATEST ENSEMBLES
ARE IN LINE WITH THE LATEST HI-RES GUIDANCE IN LIFTING THE SURFACE
LOW THROUGH THE CENTER OF THE FORECAST AREA. THIS WOULD THEN TURN
SURFACE WINDS TO OUT OF THE WEST BOTH WITHIN AND BEHIND THE LOW. THE
WESTERLY WINDS WILL ADVECT MUCH DRIER AIR INTO THE AREA. THIS DRIER
AREA WILL MAKE FOR A MUCH NARROWER WARM SECTOR WITH THE BEST
INSTABILITY RESIDING JUST ALONG THE WARM FRONT ITSELF WHERE MOISTURE
IS STILL ABLE TO POOL. CAPE VALUES LOOK TO REACH UP TO 1500 TO 2000+
J/KG ALONG THE FRONT IN TANDEM WITH MORE THAN SUFFICIENT VERTICAL
SHEAR IN PLACE THANKS FOR AN UPPER LEVEL JET SITTING OVER THE AREA.
AS OF NOW, THE BEST CONVERGENCE ALONG THE WARM FRONT IS ALONG
HIGHWAY-14 FROM BROOKINGS, SOUTH DAKOTA TO MARSHALL, MINNESOTA. THIS
LOOKS TO BE THE MAIN AREA FOR CONVECTIVE DEVELOPMENT AS SUFFICIENT
LOW LEVEL MOISTENING AND CONVERGENCE LOOKS TO BE JUST ENOUGH TO
OVERCOME THE CAP. SHOULD STORMS DEVELOP, IT LOOKS TO BE A SMALLER
NUMBER OF STORMS, ONLY ABOUT 1 TO 3 STORMS. THUS, LARGE HAIL UP TO 2
INCHES IN DIAMETER, 70 MPH WINDS, AND AN ISOLATED TORNADO IS
POSSIBLE. THE MAIN TIMEFRAME FOR CONVECTION WOULD BE BETWEEN 3 PM TO
9 PM.
TUESDAY WILL BE A QUIETER DAY AS MONDAY'S BOUNDARY WILL BE PUSHED
OFF TO THE SOUTHEAST. THIS WILL KEEP ANY INSTABILITY ALONG WITH
STRONG TO SEVERE STORM CHANCES OUT OF THE AREA. HOWEVER, THERE
REMAINS THE POTENTIAL FOR SOME LIGHT RAIN IF A DEFORMATION ZONE CAN
SET UP. THOUGH IF IT DOES, ANY RAINFALL WOULD BE LIGHT AT A TENTH OF
AN INCH OR LESS. TUESDAY WILL ALSO BE SLIGHTLY COOLER WITH HIGH
TEMPERATURES IN THE UPPER 60S TO UPPER 70S.
CHANCES FOR STRONG TO SEVERE STORMS LOOK TO CONTINUE THROUGH THE
REST OF THE WEEK. WEDNESDAY COULD BE THE NEXT CHANCE FOR SEVERE
WEATHER AS MEDIUM RANGE GUIDANCE SHOWS ANOTHER WAVE PUSHING THROUGH
THE AREA. THESE MODELS DO SHOW THAT THIS WAVE MAY CLOSE OFF WHICH
COULD BRING A WARM FRONT FURTHER NORTH, THUS BRINGING MORE
INSTABILITY WITH IT. AS OF NOW, THE ENSEMBLES SHOW THE LOW STAYING
SOUTH AND EAST OF THE FORECAST AREA. WILL STILL KEEP AN EYE ON
TRENDS OVER THE COMING DAYS IN CASE THE LOW COMES NORTH. AS OF NOW,
HIGH TEMPERATURES LOOK TO WARM TO THE UPPER 60S TO LOW 70S.
THURSDAY LOOKS TO BE A QUIET DAY AS SHORTWAVE RIDGING PUSHES THROUGH
THE PLAINS. A STRONGER UPPER LEVEL WAVE LOOKS TO EJECT INTO THE
PLAINS ON FRIDAY. A STRONGER COLD FRONT WILL BE TIED TO THIS WAVE.
SEVERE STORMS COULD BE POSSIBLE ALONG THIS FRONT THOUGH CURRENTLY
MEDIUM RANGE GUIDANCE SHOWS THE COLD FRONT EITHER JUST ABOUT TO
FULLY PUSHING THROUGH THE FORECAST AREA BY FRIDAY EVENING. THIS
COULD PRECLUDE SEVERE WEATHER CHANCES IF THE FRONT PUSHES THROUGH
THE FORECAST AREA QUICKLY. SOMETHING TO KEEP AN EYE ON AS WE
PROGRESS THROUGH THE WEEK. CHANCES FOR PRECIPITATION COULD CONTINUE
THROUGH SATURDAY BEFORE DRY CONDITIONS RETURN FOR SUNDAY.
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 657 PM CDT SUN APR 12 2026
VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. GUSTY NORTHWEST
WINDS ARE BEGINNING TO DECREASE THIS AFTERNOON AND WILL GRADUALLY
BECOME LIGHT AND VARIABLE AFTER SUNSET. THERE IS A 30-40% CHANCE OF
PATCHY FOG DEVELOPMENT TONIGHT FOCUSED OVER NORTHWEST IOWA,
INCLUDING KSUX. VISIBILITY MAY DROP TO LESS THAN 2 MILES AT TIMES.
FOG IS EXPECTED TO BURN OFF BY MID-MORNING.
A FEW LIGHT SHOWERS ARE POSSIBLE OVER CENTRAL SOUTH DAKOTA EARLY
MONDAY MORNING, MOVING NORTHEAST THROUGH ABOUT DAYBREAK. CONFIDENCE
IN SHOWERS FORMING IS LOW, LESS THAN 20%, SO HAVE LEFT THEM OUT OF
KHON AT THIS TIME. AS THE DAY CONTINUES CHANCES FOR THUNDERSTORMS
INCREASE (30-50%) FOR AREAS ALONG AND NORTH OF I-90, TO INCLUDE KFSD
AND KHON. A FEW OF THESE STORMS COULD BE STRONG TO SEVERE PRODUCING
LARGE HAIL (2+ INCHES) AND WIND GUSTS UP TO 70 MPH. THE AREA MOST
LIKELY TO SEE SEVERE STORMS IS ALONG HIGHWAY 14 IN SOUTHWEST
MINNESOTA. WHILE UNLIKELY, A TORNADO IN THIS AREA IS POSSIBLE.
STORMS WILL MOVE NORTHEAST THROUGH THE END OF THE TAF PERIOD.
FIRE WEATHER
ISSUED AT 243 PM CDT SUN APR 12 2026
TEMPERATURES HAVE WARMED TO THE 70S TO LOW 80S ACROSS THE AREA. DEW
POINTS HAVE LOWERED TO THE MID 30S TO 40S ACROSS THE MAJORITY OF THE
AREA. THE EXCEPTION IS LOCATIONS ACROSS NORTHWEST IOWA AND PARTS OF
SOUTHWEST MINNESOTA WHERE DEW POINTS HAVE REMAINED IN THE 50S TO
ABOUT 60F. THUS, HUMIDITY VALUES HAVE FALLEN TO ABOUT 20-30% ACROSS
THE MAJORITY OF THE FORECAST AREA, EXCLUDING NORTHWEST IOWA AND
PARTS OF SOUTHWEST MINNESOTA. WINDS REMAIN WESTERLY WITH GUSTS
CONTINUING TO REMAIN ABOVE 30 MPH. THUS, CRITICAL FIRE DANGER
CONDITIONS HAVE BEEN MET. HAVE EXPANDED THE RED FLAG WARNING ANOTHER
ROW OF COUNTIES NORTH AND EAST TO ACCOUNT FOR THE REST OF THE FIRE
DANGER. THE RED FLAG WARNING REMAIN IN EFFECT UNTIL 7 PM THIS
EVENING WHEN COOLING TEMPERATURES AND WEAKENING WINDS WILL END THE
FIRE DANGER.
ELEVATED FIRE DANGER REMAINS POSSIBLE TOMORROW AS LOW HUMIDITY IS
EXPECTED ALONG THE MISSOURI RIVER VALLEY. HOWEVER, WINDS WILL BE
MUCH LIGHTER AS THEY TURN FROM SOUTHEASTERLY TO WESTERLY WITH GUSTS
ONLY UP TO 15 TO 25 MPH. THUS, ONLY HIGH FIRE DANGER IS
EXPECTED.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...AJP
DISCUSSION...MEYERS
AVIATION...AJP
FIRE WEATHER...MEYERS
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