236
FXUS63 KFSD 262357
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
657 PM CDT SAT SEP 26 2026
KEY MESSAGES
- STEADY RAIN/DRIZZLE EXITS OFF TO THE NORTHEAST THROUGH THE
AFTERNOON. SCATTERED SHOWERS WILL REDEVELOP THIS AFTERNOON
MAINLY EAST OF THE JAMES RIVER, BUT NOT EVERYONE WILL GET
RAIN FROM THIS ACTIVITY.
- ADDITIONAL SHOWERS AND STORMS LOOK TO REDEVELOP IN NORTHWEST
IOWA THIS EVENING INTO THE EARLY OVERNIGHT. SEVERE WEATHER IS
NOT EXPECTED, BUT BRIEF HEAVY DOWNPOURS CAN BE EXPECTED IF A
THUNDERSTORM DEVELOPS.
- AFTER A BRIEF BREAK LATE SUNDAY INTO MONDAY, RAIN CHANCES
RETURN MONDAY NIGHT INTO TUESDAY. POCKETS OF HEAVIER RAINFALL
WILL AGAIN BE THE PRIMARY CONCERN.
DISCUSSION
ISSUED AT 257 PM CDT SAT SEP 26 2026
THE AREA OF STEADY MODERATE RAIN THAT IMPACTED THE AREA
THIS MORNING IS EXITING OFF TO OUR NORTHEAST; HOWEVER, PATCHY
DRIZZLE CONTINUES AND WILL CONTINUE ON AND OFF THROUGH THE AFTERNOON
WHERE CLOUDS CEILINGS ARE LOWEST, WHICH IS GENERALLY FROM FAR
EASTERN SOUTH DAKOTA INTO SOUTHWEST MINNESOTA. FARTHER WEST, WE'VE
SEEN SOME BREAKS IN THE LOWEST CLOUDS, ALLOWING FOR SOME
DESTABILIZATION TO OCCUR. UP TO 500-1,000 J/KG OF MLCAPE HAS
DEVELOPED PER LATEST SPC MESOANALYSIS ALONG THE MISSOURI RIVER
VALLEY, AND AS A SECONDARY MID LEVEL WAVE MOVES ACROSS THE AREA, A
FEW WEAK THUNDERSTORMS HAVE ALREADY DEVELOPED OVER NORTHERN NEBRASKA
AND ARE LIFTING NORTHWARD. SEVERE WEATHER IS NOT EXPECTED GIVEN WEAK
SHEAR ACROSS THE AREA, BUT WE WILL LIKELY CONTINUE TO SEE SOME
ADDITIONAL SHOWERS AND ISOLATED THUNDERSTORMS DEVELOP THROUGH THE
AFTERNOON AND EVENING. THE BEST CHANCE OF RAIN (30-60%) WITH THIS
ACTIVITY WILL BE OVER WESTERN IOWA, FAR NORTHEAST NEBRASKA, AND FAR
SOUTHEAST SOUTH DAKOTA, STRETCHING TO FAR SOUTHERN MINNESOTA BY THE
LATE NIGHT HOURS. TALL, SKINNY CAPE PROFILES AND DEEP WARM CLOUD
LAYERS SUGGEST HEAVY RAIN WILL BE THE PRIMARY THREAT WITH ANY
THUNDERSTORM. THIS COULD LEAD TO A FEW POCKETS OF PONDING IN LOW-
LYING AND POOR DRAINAGE AREAS, BUT FLASH FLOODING IS UNLIKELY.
HEADING INTO TONIGHT, THE AREAS THAT SAW SOME CLEARING STRATUS
(PRIMARILY NEAR AND WEST OF THE JAMES RIVER) WILL SEE SOME FOG
DEVELOP, MEANWHILE THE STRATUS DECK ELSEWHERE IS EXPECTED TO LOWER
THROUGH THE NIGHT AND BECOME FOG. LOCALLY DENSE FOG IS LIKELY GIVEN
ALL THE NEAR SURFACE MOISTURE, THOUGH COVERAGE AND EXACT LOCATIONS
WHERE THE DENSEST FOG WILL RESIDE PRECLUDES A NEED FOR A DENSE FOG
ADVISORY AT THIS TIME, BUT TRENDS WILL BE MONITORED. THIS FOG WILL
GRADUALLY LIFT THROUGH THE MID MORNING HOURS, BUT LIKELY BECOME LOW
STRATUS HEADING INTO MUCH OF THE DAY ON SUNDAY. STILL THE POTENTIAL
FOR SOME OF THIS STRATUS TO MIX OUT A BIT AND ALLOW FOR BRIEF BREAKS
OF SUN MAINLY NEAR AND WEST OF THE JAMES RIVER, BUT THIS WILL LIKELY
BE THE EXCEPTION, NOT THE NORM ACROSS THE AREA. SOME INSTABILITY IN
THE LOW CLOUD LAYER MAY ALLOW FOR A FEW SPRINKLES TO SPITS OF
DRIZZLE, BUT IT'S NOT LOOKING AS PERSISTENT AS IT HAS BEEN THE PAST
COUPLE OF DAYS.
HEADING INTO EARLY NEXT WEEK, A TROUGH OVER THE WEST COAST WILL
BEGIN TO DIG INTO THE DESERT SOUTHWEST. AHEAD OF THIS, AN UPPER
WAVE WILL MOVE INTO THE AREA LATE MONDAY INTO THE DAY ON
TUESDAY AND BRING OUR NEXT ROUND OF RAIN AND STORMS TO THE AREA.
LATEST GEFS SHOWS AROUND A 30-40% CHANCE OF AT LEAST AN INCH OF
RAIN MAINLY FOCUSED OVER NORTHWEST IOWA AND ADJACENT AREAS. THIS
IS A BIT HIGHER THAN OTHER GUIDANCE, BUT APPEARS TO BE THE MOST
REASONABLE AT THIS TIME GIVEN ENSEMBLE PWATS SHOW ANOMALIES
NEARLY OF +1" IN PLACE AS THIS SYSTEM MOVES THROUGH. THE
AFOREMENTIONED TROUGH OVER THE DESERT SOUTHWEST WILL ABSORB THE
REMNANTS OF A PACIFIC OCEAN TROPICAL CYCLONE AS IT EJECTS TO
THE NORTH AND EAST DURING THE MIDDLE TO END OF THE NEXT WORK.
THIS MAY HELP TO KEEP A DECENT AMOUNT OF MOISTURE IN PLACE OVER
PRIMARILY NORTHWESTERN IOWA INTO THE END OF THE UPCOMING WORK
WEEK, THOUGH AT THIS POINT IT LOOKS LIKE THE HEAVIEST RAIN
ASSOCIATED WITH THIS WILL STAY SOUTH OF THE AREA.
AVIATION /00Z TAFS THROUGH 00Z MONDAY/
ISSUED AT 638 PM CDT SAT SEP 26 2026
MAINLY MVFR TO IFR CONDITIONS AND LOWER WILL CONTINUE THIS TAF
PERIOD. CONTINUING TO WATCH THE SHOWERS ACROSS NORTHWESTERN IA
THIS EVENING. SHOULD SEE THIS ACTIVITY CONTINUE TO LIFT
NORTHEAST OVER THE NEXT FEW HOURS BEFORE EXITING OUR AREA.
OTHERWISE, SHOULD SEE LIGHT AND VARIABLE WINDS RETURN OVERNIGHT
AS CEILINGS GRADUALLY LOWER. WIDESPREAD IFR TO LIFR CONDITIONS
ARE EXPECTED THROUGH MID-MORNING ON SUNDAY WITH AREAS OF DRIZZLE
AND FOG DEVELOPING. CURRENT THINKING IS THE DRIZZLE WILL BE
MOSTLY CONFINED TO AREAS ALONG AND EAST OF I-29 SO ADDED -DZ TO
KFSD AND KHON THROUGH THE MORNING HOURS. LASTLY, LIGHT AND
VARIABLE WINDS WILL GRADUALLY BECOME MORE EASTERLY BY SUNDAY
AFTERNOON.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...SAMET
AVIATION...05
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