780
FXUS63 KFSD 021728
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1228 PM CDT TUE JUN 2 2026
KEY MESSAGES
- UNSETTLED CONDITIONS REMAIN IN THE REGION THROUGH THE WEEK.
SPOTTY SHOWERS AND NON-SEVERE STORMS ARE POSSIBLE WEST OF I-29
THIS AFTERNOON, WITH A LOW CONFIDENCE RISK OF STRONG WINDS
TOWARD CENTRAL SOUTH DAKOTA AFTER MIDNIGHT TONIGHT.
- PORTIONS OF SOUTHEAST SOUTH DAKOTA WILL SEE A LEVEL 2 OF 5
RISK FOR SEVERE STORMS WEDNESDAY EVENING AND THURSDAY NIGHT,
WITH LESSER RISKS FARTHER EAST AND SOUTH. LARGE HAIL AND
DAMAGING WINDS ARE THE PRIMARY THREATS DURING THESE PERIODS.
- TEMPERATURES REMAIN IN THE 80S THROUGH THE WEEK AND RISE
TOWARDS THE UPPER 80S BY THE END OF THE WEEKEND.
UPDATE
ISSUED AT 544 AM CDT TUE JUN 2 2026
A MILD START TO THE DAY WITH TEMPERATURES LARGELY IN THE MID TO
UPPER 60S AS OF 5 AM. NOT MANY CHANGES TO THE FORECAST FOR TODAY
AND TONIGHT, WHICH IS DISCUSSED IN DETAIL IN THE EARLIER UPDATE
BELOW.
SEVERE RISKS FOR LATE WEDNESDAY AND THURSDAY NIGHT HAVE EXPANDED
EASTWARD, WITH A LEVEL 2 OF 5 RISK FOR PORTIONS OF SOUTHEAST
SOUTH DAKOTA IN EACH PERIOD. FOR WEDNESDAY, THE GREATER RISK IS
NORTHWEST OF LAKE ANDES TO MADISON TO BROOKINGS SOUTH DAKOTA.
AS ALLUDED TO BELOW, THE MAIN CONCERN LATE WEDNESDAY IS THE
POTENTIAL FOR A SCATTERED LINE OF THUNDERSTORMS DEVELOPING FROM
CENTRAL SOUTH DAKOTA TO EASTERN NORTH DAKOTA MID-LATE AFTERNOON.
DEVELOPING STORMS COULD QUICKLY BECOME SEVERE, BRINGING A RISK
OF LARGE HAIL TO 2 INCHES OR LARGER, ALONG WITH DAMAGING WIND
GUSTS TO 70 MPH INTO THE MIDDLE JAMES RIVER VALLEY BY EARLY
EVENING. CAMS VARY IN STORM COVERAGE, BUT ARE SHOWING DECENT
CONSENSUS IN THE LOCATION/TIMING OF POTENTIAL DEVELOPMENT IN
CENTRAL SD 20-22Z WITH ACTIVITY ADVANCING INTO OUR FAR WESTERN
COUNTIES 22Z-00Z (5PM-7PM WEDNESDAY). STORMS PROGRESS EAST AND
SOUTHEAST DURING THE EVENING, BECOMING LESS ORGANIZED AND
WEAKENING AS THEY MOVE INTO SOUTHWEST MN AND FAR SOUTHEAST SD AS
WE APPROACH MIDNIGHT.
THURSDAY'S EVOLUTION IS LOWER CONFIDENCE, AND IF WE CAN CLEAR
EARLY ENOUGH TO ALLOW DESTABILIZATION, CANNOT RULE OUT ISOLATED
STORMS ALONG A LINGERING BOUNDARY IN THE LATE AFTERNOON/EVENING.
MAIN FOCUS IS ON DEVELOPMENT ACROSS WESTERN SOUTH DAKOTA IN THE
AFTERNOON, WOULD COULD EVOLVE INTO A LINE AND TRACK EAST INTO
EASTERN SD OVERNIGHT. WHILE SOME HAIL WOULD BE POSSIBLE, THE
PRIMARY THREAT IN THIS SCENARIO IS SCATTERED DAMAGING WIND GUSTS
BEFORE THE LINE MOVES INTO A LESS FAVORABLE ENVIRONMENT AND
WEAKENS.
ISSUED AT 912 PM CDT MON JUN 1 2026
HIGH PRESSURE SITTING OVER THE GREAT LAKES AREA WILL BE
ADVECTING DRIER, MORE STABLE AREA INTO THE AREA AS
EAST/SOUTHEAST FLOW PERSISTS THROUGH THE DAY TOMORROW. THIS WILL
PUSH THE INSTABILITY GRADIENT TO THE WEST. THIS GRADIENT LOOKS
TO END UP PARALLELING I-29 BY THE LATE AFTERNOON HOURS TOMORROW.
A MESOSCALE CONVECTIVE VORTEX (MCV) LOOKS TO DEVELOP FROM THE
OVERNIGHTS STORMS. THIS MCV LOOKS TO INTERACT WITH THIS
INSTABILITY GRADIENT AND DEVELOP ADDITIONAL SHOWERS AND
THUNDERSTORMS. MEAN FLOW IS ROUGHLY PARALLEL TO THE BOUNDARY
WHICH LOOKS TO ALLOW THESE SHOWERS AND STORMS TO PERSIST FROM
LATE MORNING THROUGH THE BULK OF THE AFTERNOON TIMEFRAME. DON'T
THINK ANY OF THESE STORMS WILL BE STRONG TO SEVERE AS DEEP LAYER
SHEAR IS QUITE WEAK, ON THE ORDER OF 10-15 KNOTS. HOWEVER,
BRIEF GUSTY WINDS, BRIEF HEAVY RAIN, AND SMALL HAIL ARE
POSSIBLE. THE MAIN IMPACT FROM THESE SHOWERS AND STORMS IS THAT
THE LOOK TO EITHER PARALLEL I-29 OR DEVELOP JUST TO THE WEST OF
THE INTERSTATE. EVEN THOUGH THESE STORMS ARE NOT EXPECTED TO BE
STRONG TO SEVERE, THEY CAN STILL IMPACT OUTDOOR EVENTS. A MCS
LOOKS TO DEVELOP ALONG THE BLACK HILLS AND PUSH NORTHEASTWARDS
ALONG A SURFACE BOUNDARY DRAPED FROM NORTHEAST SOUTH DAKOTA DOWN
INTO THE BLACK HILLS. THIS BOUNDARY LOOKS TO RESIDE WITHIN A
SURFACE TROUGH AND IS SOMEWHAT SUPPORTED BY CONVERGENCE IN THE
LOW LEVELS. AS THE MCS PROGRESSES NORTHEASTWARDS ALONG THE
BOUNDARY, IT LOOKS TO RUN INTO A WORSENING ENVIRONMENT AS
INSTABILITY WANES AND SHEAR WEAKENS. THIS STILL LOOKS TO SUPPORT
A LOWER END SEVERE WEATHER THREAT ALONG AND WEST OF A LAKE
ANDES, SOUTH DAKOTA TO HURON, SOUTH DAKOTA LINE WHERE LARGE HAIL
AND DAMAGING WINDS ARE POSSIBLE BEFORE THE MCS RACES OUT OF THE
AVAILABLE INSTABILITY AND WEAKENS.
ANOTHER POTENTIAL FOR STRONG TO SEVERE STORMS IS POSSIBLE ON
WEDNESDAY. WEDNESDAY IS STARTING TO LOOK MORE LIKE A LINE OF STORMS
AS ANOTHER BOUNDARY DRAPED WITHIN A SURFACE TROUGH PUSHES INTO THE
AREA. SHEAR PROFILES LOOK TO BE PARALLEL TO THE BOUNDARY, SUPPORTING
THE POTENTIAL FOR A LINE OF STORMS. THAT SAID, STILL ENOUGH
UNCERTAINTY TO NOT SAY MUCH BEYOND THAT AS TUESDAY NIGHT'S STORMS
COULD AFFECT WEDNESDAY'S STORMS.
DISCUSSION
ISSUED AT 112 PM CDT MON JUN 1 2026
THIS AFTERNOON/EVENING: RATHER STABLE CONDITIONS ACROSS THE REGION
EARLY THIS AFTERNOON, OUTSIDE OF A LONE ELEVATED STORM OVER NORTH
CENTRAL IOWA. SATELLITE SHOWS A WEAK MID-LVL WAVE CROSSING CENTRAL
NEBRASKA AND LIFTING TOWARDS THE TRI-STATE AREA. SOUNDINGS
CLOSER TO HOME SHOW A VERY STABLE LAYER THAT SHOULD PREVENT ANY
SURFACE BASED CONVECTION TO DEVELOP AS TEMPERATURES RISE TOWARDS
THE 80S. WHAT THIS WAVE MAY DO IS BRIEFLY SLOW THE RISE IN
TEMPERATURES, BUT BRING A CHANCE FOR A FEW HIGH BASED SPRINKLES.
A SECOND AREA WE'LL BE MONITORING TODAY IS RIGHT ALONG THE
EASTWARD EDGE OF THE CWA WHERE A BIT LESS INHIBITION IS IN
PLACE. WITH A VERY WEAK SHEAR PROFILE, ANY STORM THAT DEVELOPS
IS NOT EXPECTED TO BE STRONG TO SEVERE.
TONIGHT: MOST OF THE FOCUS DURING THE OVERNIGHT HOURS WILL BE
ACROSS THE NEBRASKA PANHANDLE, BLACK HILLS REGION, AND WESTERN
KANSAS. AS YET ANOTHER WAVE EJECTS OUT OF THE CENTRAL ROCKIES,
WE SHOULD SEE RENEWED CONVECTION DEVELOP AND QUICKLY TRY TO
CONGEAL INTO ONE OR MORE CLUSTERS AS THEY CROSS WESTERN
NEBRASKA AND SOUTH DAKOTA. LATEST CAMS CONTINUE TO HINT AT
THESE STORMS TRYING TO SLOWLY LIFT NORTHEAST BUT SHOULD WEAKEN
AS THEY REACH A MORE STABLE ATMOSPHERE. THAT SAID, COULD
CONTINUE TO SEE A LIMITED WIND RISK INTO SOUTH CENTRAL SOUTH
DAKOTA AND ALONG PORTIONS OF THE MISSOURI RIVER VALLEY BY 3AM.
FURTHER NORTH, THE ABUNDANCE OF LOW-LVL MOISTURE COMBINED WITH
LIGHT WINDS COULD LEAD TO PATCHY FOG DEVELOPING.
TUESDAY: WE'LL HAVE TO KEEP A CLOSE EYE ON THE PROGRESSION OF THE
CONVECTION IN NEBRASKA AS GUIDANCE DOES SHOW SIGNS OF A DEVELOPING
MCV THAT MAY TRACK EAST AND SLOWLY NORTH DURING THE DAY. AT THIS
POINT, DESTABILIZATION OF THE BOUNDARY LAYER WILL NEED TO BE WATCHED
AS WE COULD SEE POCKETS OF 2000 J/KG MLCAPE DEVELOP IN A NARROW
CORRIDOR AHEAD OF THIS WAVE. ISOLATED TO SCATTERED STORMS COULD
DEVELOP BASED ON THE WEAKENING OF CONVECTIVE INHIBITION
SOMEWHERE BETWEEN THE JAMES RIVER AND I-29. EFFECTIVE SHEAR
REMAINS VERY WEAK. BUT THERE MAY STILL BE APPRECIABLE 0-1KM
HELICITY TO LEAD TO A FEW ROTATING STORMS/FUNNELS. HOWEVER THE
WIDESPREAD SEVERE RISK REMAINS LOW AND MORE FOCUSED ON MARGINAL
HAIL, BUT COULD SEE FUTURE OUTLOOKS EXTENDED FURTHER EAST.
BETTER FOCUS FOR CONVECTION WILL BE ACROSS FAR WESTERN SD ALONG
A FRONTAL BOUNDARY EDGING INTO THE STATE. AS YET ANOTHER WAVE
EJECTS INTO THE PLAINS SCATTERED CONVECTION ALONG THIS BOUNDARY
SHOULD DEVELOP AND BEGIN TO TRACK EAST NORTHEAST. ONE THING TO
NOTE TODAY IS THAT MID-LVL HEIGHTS MAY BE RISING ACROSS CENTRAL
SD IN THE EVENING, WITH 700 MB TEMPERATURES ALSO RISING. THE
MORE MERIDIONAL 700:500 FLOW SHOULD PREVENT A STRONG EASTWARD
SHIFT AFTER DARK.
WEDNESDAY/THURSDAY: UNCERTAINTY GROWS WITH THE WEDNESDAY AND
THURSDAY FORECAST AS WE REMAIN STUCK IN THIS GENERAL MID-LVL
SOUTHWESTERLY FLOW PATTERN. THE AFOREMENTIONED FRONT WILL ATTEMPT TO
SLIDE EASTWARD ON WEDNESDAY, THOUGH A MUCH MORE E COMPLICATED
FORECAST IN REGARDS TO THE ENVIRONMENT AHEAD OF THE FRONT. YET
ANOTHER WEAK MID-LVL AREA OF VORTICITY TRACKS THROUGH THE TRI-STATE
AREA, INCREASING THE RISKS FOR MID-LVL CLOUDS BUT ALSO A FEW SHOWERS
AND ISOLATED THUNDERSTORMS BY THE AFTERNOON. THE AREA WITH THE
GREATEST RISKS FOR STRONG CONVECTION WILL BE ALONG THAT FRONTAL
BOUNDARY IN CENTRAL SOUTH DAKOTA BY MID-LATE AFTERNOON. ADDITIONAL
SHOWERS AND THUNDERSTORMS MAY BE POSSIBLE INTO THE OVERNIGHT
HOURS FURTHER EAST AS THE LLJ INTENSIFIES. LATEST NBM GUIDANCE
SUGGESTS 8- 95% POPS IN THIS TIMEFRAME, BUT MY CONFIDENCE IN
OVERALL COVERAGE IS NOT AS HIGH AS THAT CHANCE SUGGESTS. A BIT
OF A REPEAT PERFORMANCE ON THURSDAY, WITH THE GREATEST SEVERE
RISKS AGAIN FOCUSED WEST OF THE JAMES RIVER AND INTO
SOUTHWESTERN SOUTH DAKOTA BY THE AFTERNOON.
FRIDAY-SUNDAY: MID-LVL TROUGHING MOVES THROUGH THE DAKOTAS ON
FRIDAY, POTENTIALLY PUSHING STRONG CONVECTIVE RISKS FURTHER EAST
INTO MN/IA. CONFIDENCE IS VERY LOW IN THIS TIME PERIOD GIVEN ALL OF
THE VARIOUS UNCERTAINTY ASSOCIATED WITH THE FORECAST IN THE DAYS
BEFORE. CONFIDENCE RISES FOR NEXT WEEKEND WITH DRIER WEATHER AND
NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES LIKELY.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 1225 PM CDT TUE JUN 2 2026
MAINLY VFR CONDITIONS WILL CONTINUE THIS TAF PERIOD. BESIDES
SOME HIGH-LEVEL CIRRUS, MOSTLY QUIET CONDITIONS PERSIST THIS
AFTERNOON. COULD SEE A FEW SCATTERED SHOWERS LIFT THROUGH THE
AREA STARTING TONIGHT MAINLY AS THE LLJ STRENGTHENS. DECIDED TO
ADD A PROB30 GROUP TO KHON TO ACCOUNT FOR THE INCREASED
PROBABILITIES. OTHERWISE, OVERCAST CONDITIONS WILL PERSIST FOR
MOST OF THE DAY ON WEDNESDAY.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...JH
DISCUSSION...DUX
AVIATION...05
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