477
FXUS63 KFSD 231938
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
238 PM CDT SUN AUG 23 2026
KEY MESSAGES
- SHOWERS AND STORMS SHOULD BE A BIT MORE WIDESPREAD TONIGHT
(50- 70%). LOCALLY HEAVY RAIN AND ISOLATED SEVERE STORMS ARE
POSSIBLE. COVERAGE AND INTENSITY HAVE BEEN TRENDING DOWN A
BIT HOWEVER.
- MONDAY EVENING AND NIGHT COULD SEE AN ISOLATED SEVERE STORM,
WITH THE BETTER CHANCES IN CENTRAL SD AND ALSO NEAR HIGHWAY
14.
- OTHERWISE MOST DAYS THROUGH NEXT WEEK WILL SEE HIGHS IN THE
80S AND LOWS IN THE UPPER 50S TO MID 60S.
DISCUSSION
ISSUED AT 237 PM CDT SUN AUG 23 2026
A PAIR OF WAVES ARE AFFECTING THE AREA, OR NEARBY, TODAY. THE FIRST
IS MOVING SOUTHEAST THROUGH NEBRASKA AND IS KEEPING ANY INSTABILITY
TO THE SOUTH AND WEST BOTTLED UP. MODEL SOUNDINGS NOT HINTING AT A
WHOLE LOT OF ACTIVITY THIS AFTERNOON, WITH A FAIRLY DRY AND STABLE
AIR MASS IN PLACE.
TONIGHT A SECOND WAVE WILL PASS BY TO THE NORTH AND WILL SWING A
LITTLE BIT OF MID LEVEL MOISTURE INTO THE AREA. AS THIS MOISTURE
MOVES IN, SOME WEAK ELEVATED INSTABILITY, LIKELY 500-750 J/KG CAPE
DEVELOPS. THIS WILL SUPPORT SOME SCATTERED SHOWER AND ISOLATED
THUNDERSTORM ACTIVITY, BUT FOR NOW SEVERE WEATHER LOOKS
UNLIKELY. A FEW POCKETS OF HEAVIER RAIN ARE ALSO POSSIBLE, BUT
ALSO TRENDING DOWNWARD.
MONDAY WILL SEE TEMPERATURES WARM A BIT WITH HUMIDITY LIKELY TO
INCREASE AS WELL. THIS IS IN RESPONSE TO STRENGTHENING SOUTHERLY
FLOW AS A STRONGER WAVE MOVES EAST ALONG THE CANADIAN BORDER. THIS
WILL INCREASE INSTABILITY, ESPECIALLY TO THE NORTHWEST OF THE AREA,
AND SHOULD BRING SCATTERED THUNDERSTORMS TO PARTS OF CENTRAL SD AND
NEAR THE HIGHWAY 14 CORRIDOR. WITH THE POTENTIAL FOR ABOUT 1000-1500
J/KG CAPE AND DECENT UNIDIRECTIONAL SHEAR, AND ISOLATED SEVERE STORM
WILL BE POSSIBLE IN THESE LOCATIONS. ONE AREA TO WATCH WILL BE NEAR
NORTHWEST IA LATE MONDAY AFTERNOON AND EVENING WHERE THERE ARE SOME
HINTS THE CAP COULD WEAKEN A BIT AS ELEVATED MOISTURE ADVECTION
BRING SOME INSTABILITY TO THAT AREA. LOW CONFIDENCE, BUT SOMETHING
TO MONITOR.
NORTHWEST FLOW ALOFT TUESDAY INTO THE WEEKEND WILL KEEP SEASONALLY
WARM TEMPERATURES IN PLACE WITH HIGHS IN THE 80S AND LOWS FROM THE
UPPER 50S TO MID 60S. STARTING TO SEE A LITTLE MORE CONSISTENCY ON
THE NEXT BETTER CHANCE FOR SHOWERS AND THUNDERSTORMS ON FRIDAY. THE
LATEST CANADIAN, GEFS AND EC ENSEMBLES ALL INDICATE ABOUT A 30-5-
PERCENT CHANCE FOR A TENTH OF AN INCH OR MORE OF PRECIPITATION.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1216 PM CDT SUN AUG 23 2026
THE MAIN CONCERN THIS TAF PERIOD WILL BE THE CHANCE FOR SHOWERS
AND STORMS. WHILE ISOLATED TO SCATTERED, THE BETTER CHANCES WILL
BE FROM ABOUT 3Z TO 12Z WITH THE BETTER CHANCES SOUTH OF I-90.
WITH ANY THUNDERSTORMS AND NEAR ANY THUNDERSTORMS, BRIEF MVFR
CONDITIONS WILL BE POSSIBLE.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...08
AVIATION...08
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