330
FXUS63 KFSD 021115
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
615 AM CDT WED SEP 2 2026
KEY MESSAGES
- SCATTERED SHOWERS AND THUNDERSTORMS REMAIN POSSIBLE LATE
TONIGHT INTO THURSDAY MORNING. SEVERE WEATHER SHOULD REMAIN
ISOLATED.
- TEMPERATURES REMAIN WELL ABOVE NORMAL THROUGH THE REST OF
THIS WEEK AND INTO THE UPCOMING WEEKEND, WITH HIGHS IN THE 90S
POSSIBLE BY MID-LATE WEEK.
- THE HEAT AND HUMIDITY MAY BRING OCCASIONAL RISKS FOR ISOLATED
OVERNIGHT THUNDERSTORMS. EXACT LOCATIONS OF STORMS REMAIN
UNCERTAIN.
UPDATE
ISSUED AT 259 AM CDT WED SEP 2 2026
SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DECREASE IN COVERAGE
EARLY THIS MORNING. WITH A BROAD TROUGH OVER THE ROCKIES, ANOTHER
WEAK WAVE IS EXPECTED TO MOVE INTO THE AREA TODAY. THIS WILL BRING
WARMER AND MORE MOIST AIR BACK TO THE NORTH WITH ELEVATED CAPE
VALUES AROUND 1000-1500 J/KG EXPECTED. THROUGH THE DAY CAPPING IS
EXPECTED TO HOLD, BUT DURING THE NIGHTTIME HOURS, THE LLJ IS
EXPECTED TO INCREASE AND FOCUS INTO THE AREA, ESPECIALLY NEAR AND
EAST OF I-29. FAIRLY STRONG UNIDIRECTIONAL SHEAR WILL LIKELY ALLOW
FOR ISOLATED STRONG TO SEVERE STORMS ONCE AGAIN AROUND THE
AFOREMENTIONED AREA. RIGHT NOW THE BETTER CHANCE FOR SEVERE WEATHER
LOOKS TO BE FROM LATE TONIGHT INTO THURSDAY MORNING.
OTHERWISE, THE TROUGH OVER THE ROCKIES DEEPENS AND BUILDS A RIDGE
ACROSS THE NORTHERN AND CENTRAL PLAINS THURSDAY AFTERNOON INTO THE
WEEKEND. THIS WILL BRING VERY WARM AND HUMID CONDITIONS WITH HIGHS
FROM 85 TO 95 EACH DAY WITH DEW POINT TEMPERATURES LIKELY 65 TO 75
EACH DAY. THIS WILL PUSH HEAT INDICES TO 90 TO 100 ACROSS THE AREA.
IF YOU HAVE OUTDOOR PLANS DURING THIS TIME, PLEASE PLAN AHEAD FOR
THESE HOT AND HUMID CONDITIONS.
DISCUSSION
ISSUED AT 111 PM CDT TUE SEP 1 2026
THIS AFTERNOON: A COMPLEX CONVECTIVE SETUP THIS AFTERNOON AS A PAIR
OF MID-LVL VORTICITY CENTERS CONTINUE TO PIVOT NORTHEAST. ONE
SUCH AREA CONTINUES TO PUSH NORTH OF SIOUX FALLS, WITH A SECOND
STRONGER AREA OF ENERGY NOW LIFTING NORTHWARD THROUGH THE
NEBRASKA PANHANDLE. THE RESULT THUS FAR HAS BEEN A SIGNIFICANTLY
CONTAMINATED WARM SECTOR WITH PLENTY OF MID-UPR CLOUDS OVER THE
TRI-STATE REGION. AT THE SURFACE, A STATIONARY BOUNDARY/WARM
FRONT CURRENTLY STRETCHES FROM THE PLATTE RIVER TO NORTH OF
OMAHA AND NORTH OF AMES. THE AIRMASS NORTH OF THIS BOUNDARY
CONTINUES TO WARM, SUGGESTING SOME POTENTIAL FOR A NORTHWARD
PUSH IN THIS FRONT BY EVENING AS DEEPER SYNOPTIC LIFT ARRIVES,
BUT FOR THE MOST PART THIS AREA WILL REMAIN CAPPED TO SURFACE
BASED CONVECTION INTO LATE AFTERNOON.
LATE AFTERNOON/EVENING/TONIGHT: WE'LL CONTINUE TO SEE MLCAPE VALUES
CLIMB UPWARDS THROUGH THE AFTERNOON, POTENTIALLY BETWEEN
2000-3000 J/KG, BUT HOW FAR NORTH WITH THIS INSTABILITY REACH IS
STILL UNCERTAIN. ONGOING ELEVATED CONVECTION IN NC NEBRASKA MAY
KEEP SOME AREAS NORTH OF I-90 FROM ANY SIGNIFICANT LEVEL OF
DESTABILIZATION, WITH THE LARGEST RESERVOIR OF CAPE ALONG AND
ESPECIALLY SOUTH OF I- 90. MOST GUIDANCE WOULD FAVOR NEW
CONVECTIVE DEVELOPMENT ALONG AN SURFACE CONVERGENCE ZONE IN NE
NEBRASKA OR SC SOUTH DAKOTA AFTER 5PM IN A NARROW CORRIDOR OF
DEEPER INSTABILITY. GIVEN FAVORABLE SHEAR PROFILES (EFFECTIVE
SHEAR 40+ KNOTS), ANY INITIAL DEVELOPMENT SHOULD HAVE
SUPERCELLULAR CHARACTERISTICS CAPABLE OF 2" HAIL AND 70 MPH
WINDS. ADDITIONAL CONVECTION MAY TRY TO DEVELOP OVER CENTRAL
NEBRASKA AND LIFT NORTHWARD TO THE MO RIVER IN THE EVENING. AS
WE MOVE THROUGH THE MID-LATE EVENING HOURS, 0-1KM SHEAR WILL BE
ON THE RISE AS THE LLJ DEVELOPS, INTRODUCING AT LEAST THE LOW
END POTENTIAL FOR A BRIEF TORNADO SOUTH OF I-90 IF STORMS CAN
STAY DISCRETE. THOUGH BOUNDARY LAYER STABILIZATION WILL BE ON
THE INCREASE AND LCLS REMAIN QUITE HIGH. OTHERWISE, WATCH FOR
GRADUAL CLUSTERING OF STORMS AS THEY TRACK EAST NORTHEAST INTO
MN/IA WHICH WOULD INCREASE THE POTENTIAL OF 70+ MPH WINDS, WITH
A CONTINUED VERY LOW PROBABILITY OF A QLCS- LIKE TORNADO INTO NW
IOWA. 17Z SSCRAM-HRRR DATA WOULD SUPPORT THE RISING POTENTIAL
FOR HIGH WINDS EXTENDING NORTH OF HIGHWAY 20, WITH BRIEF HAIL
POTENTIAL IN NEW UPDRAFTS DRIVEN BY THE LLJ FURTHER NORTH INTO
WESTERN MN. LATEST PROJECTIONS CONTINUE TO PUSH CONVECTION EAST
OF THE CWA BY 2AM, WITH LIGHT WINDS AND WET GROUND PERHAPS
ALLOWING PATCH FOG TO DEVELOP.
WEDNESDAY: BRIEF SHORTWAVE RIDGING TRIES TO MOVE IN EARLY WEDNESDAY
AS THE SURFACE FRONT SETTLES BACK INTO EASTERN NEBRASKA AND
NORTH CENTRAL IOWA. A FEW LINGERING ELEVATED
SHOWERS/THUNDERSTORMS MAY PERSIST INTO NW IOWA THROUGH MID-
MORNING. WITH A SLIGHTLY DRIER EASTERLY WIND, TEMPERATURES AGAIN
RISE INTO THE MIDDLE TO UPPER 80S, WITH THE LATEST GUIDANCE
SUPPORTING A STRONG ENOUGH EML TO PREVENT CONVECTION ALONG THE
BOUNDARY. THE RETURN OF THE NOCTURNAL LLJ WEDNESDAY NIGHT COULD
AGAIN LEAD TO ISOLATED TO SCATTERED ELEVATED CONVECTION INTO
THURSDAY MORNING.
THURSDAY-FRIDAY: CONFIDENCE REMAINS RATHER HIGH THAT TEMPERATURES
CONTINUE TO RISE TOWARDS THE LOWER 90S IN MOST LOCATIONS FOR THE END
OF THE WEEK. INCREASING MID-LVL HEIGHTS THROUGH THE PLAINS WILL HELP
PUSH LOW-LVL TEMPERATURES WELL ABOVE NORMAL, WITH H850 TEMPS +26C
THURSDAY AND FRIDAY. THE GREATEST CHALLENGE IN THE MEDIUM RANGE
WILL BE TIMING AND TRACKING ONE OR MORE WEAK RIDGE RIDERS THAT WILL
CROSS THE PLAINS INTO THE WEEKEND. ONCE SUCH WAVE MAY DROP DOWN
FROM THE NW INTO MINNESOTA EARLY FRIDAY MORNING, PERHAPS LEAVING AN
OUTFLOW BOUNDARY NEAR THE MINNESOTA RIVER/RIDGE AREAS FOR THE
AFTERNOON.
SATURDAY-MONDAY: TEMPERATURES REMAIN ABOVE NORMAL THROUGH THE
WEEKEND AND INTO EARLY NEXT WEEK AS THE 500 MB RIDGE PEAKS THROUGH
THE CENTRAL CONUS. ONE OR MORE WEAK WAVES TOP THE RIDGE DURING THE
WEEKEND, CREATING A VERY LOW CONFIDENCE POP FORECAST DURING THE
OVERNIGHT HOURS. SHOULD ONE OF THESE WAVES TRACK CLOSE ENOUGH TO
THE CWA THEY COULD LEAD TO SOME TEMPERATURE REDUCTIONS.
AVIATION /12Z TAFS THROUGH 12Z THURSDAY/
ISSUED AT 614 AM CDT WED SEP 2 2026
IFR FOG WILL BE LIKELY IN SOUTH CENTRAL SD THROUGH MID MORNING
WITH VERY PATCHY MVFR FOG POSSIBLE ELSEWHERE DURING THIS TIME.
OTHERWISE, SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL BE
POSSIBLE LATE TONIGHT, BUT CONFIDENCE IS FAIRLY LOW AT THIS
TIME.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...08
DISCUSSION...DUX
AVIATION...08
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