219
FXUS63 KFSD 010410
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1110 PM CDT WED SEP 30 2026
KEY MESSAGES
- RAIN WILL CONTINUE LIFTING THROUGH THE U.S. HIGHWAY-20
CORRIDOR THROUGH THE EARLY MORNING HOURS. ADDITIONAL RAINFALL
AMOUNTS MAINLY LESS THAN 0.25 INCH ARE EXPECTED, BUT TOTALS
NEARING 0.50 TO LOCALLY 0.75 INCH MAY PUSH INTO FAR SOUTHERN
PORTIONS OF IDA AND WOODBURY COUNTIES.
- DRIER AND MILD CONDITIONS SETTLE INTO THE AREA WITH ONLY VERY
MINOR CHANCES FOR SHOWERS THROUGH EARLY NEXT WEEK.
UPDATE
ISSUED AT 923 PM CDT WED SEP 30 2026
THE FORECAST FOR TONIGHT REMAINS LARGELY ON TRACK. STEADY RAIN
WILL CONTINUE FOR THE HIGHWAY 20 CORRIDOR WHILE THE AREA OF RAIN
SLOWLY LIFTS NORTHEASTWARD. WILL START TO SEE SOME PERIODS OF
MODERATE RAINFALL CREEP INTO FAR SOUTHERN PORTIONS OF THE AREA
OVER THE NEXT FEW HOURS, BUT WITH ANY THUNDERSTORMS LIKELY
STAYING SOUTH, FLOODING CHANCES STILL LOOK VERY LOW. ADDITIONAL
RAINFALL AMOUNTS THROUGH TOMORROW MORNING WILL GENERALLY BE A
QUARTER OF AN INCH OR LESS, WITH SLIGHTLY HIGHER AMOUNTS
TOWARDS 0.50-0.75" ALONG AND SOUTHEAST OF A NEWELL TO IDA GROVE
TO SMITHLAND LINE. THIS IS ON TOP OF THE RAINFALL ALREADY SEEN
WHICH ACCORDING TO LATEST MRMS AND PERSONAL WEATHER STATION
OBSERVATIONS HAVE BEEN GENERALLY LESS THAN TWO TENTHS OF AN
INCH.
ELSEWHERE TONIGHT, PATCHY FOG WILL BE POSSIBLE, ESPECIALLY OVER
NORTHWESTERN IOWA WHERE CHANCES OF FOG DEVELOPMENT HAVE
INCREASED TO AROUND A 40% CHANCE. WIDESPREAD FOG IS NOT
EXPECTED AND ANY DENSE FOG WILL LIKELY BE VERY LOCALIZED.
NORTHERLY WINDS MOVING IN HEADING INTO TOMORROW MORNING AND SOME
COLD AIR ADVECTION WILL LEAD TO ANY FOG CONCERNS NOT LASTING
FOR TOO LONG INTO THE MORNING WHEREVER IT DEVELOPS. THIS COOLER
AND DRIER AIR WILL BRING SOME LOWS TONIGHT DOWN INTO THE 50S FOR
MOST OF THE AREA, BUT THE MOST NOTABLE CHANGE WILL BE DEW
POINTS FALLING FROM THE 50S INTO THE 40S AS WE HEAD THROUGH THE
DAY TOMORROW. CLOUDS WILL DECREASE FROM WEST TO EAST THROUGHOUT
THE DAY WITH HIGHS ON THURSDAY MOSTLY IN THE MIDDLE 60S WITH
SOME POCKETS OF LOWER 60S.
DISCUSSION
ISSUED AT 111 PM CDT WED SEP 30 2026
ALL INDICATIONS CONTINUE TO POINT TOWARDS KEEPING THE HEAVIER RAIN
TO THE SOUTH LATER THIS AFTERNOON AND TONIGHT. THE HIGH RESOLUTION
MODELS ONLY BRING ABOUT A QUARTER OF AN INCH OF RAIN TO SOUTHERN
PARTS OF WOODBURY AND IDA COUNTIES WITH THE ENSEMBLE OUTPUT SHOWING
ABOUT A 20-40 PERCENT CHANCE TO EXCEED 1 INCH OF RAIN, THE EC
PROBABILITIES A LITTLE HIGHER. WITH 3-4 INCHES OF RAIN NEEDED TO
MAKE ANY IF THE RIVERS REALLY MOVE UPWARDS, FLOODING CONCERNS ARE
VERY MINIMAL.
FOG WILL AGAIN BE POSSIBLE LATER TONIGHT INTO THURSDAY MORNING, BUT
FOR NOW THE MODEL SOUNDINGS SUGGEST THE LOWER LEVEL SATURATED LAYER
IS MUCH SHALLOWER, SO A BETTER CHANCE TO BURN OFF MORE QUICKLY IN
THE MORNING. A SURGE OF DRIER AIR WILL BUILD SOUTHWARD WITH DEW
POINTS FALLING INTO THE 40S THROUGH THE MORNING. ALSO LOOKS LIKE THE
BETTER CHANCES WOULD BE OVER PARTS OF NORTHWEST IA AND NEARBY
LOCATIONS.
A SYSTEM WILL MOVE BY TO THE NORTH FRIDAY INTO SATURDAY. WHILE THIS
WILL BRING SOME MID LEVEL CLOUD COVER INTO THE AREA, PRECIPITATION
CHANCES WILL REMAIN FAIRLY LOW WITH DRY AIR BELOW ABOUT 800 MB. SOME
VERY WEAK INSTABILITY ALOFT FRIDAY NIGHT INTO SATURDAY AHEAD OF AN
INCOMING SHOT OF COOLER AND DRIER AIR MAY SEE THE NEED TO ADD SOME
SPOTTY SHOWERS DURING THIS TIME, BUT CONFIDENCE FAIRLY LOW IN THIS
WEAK INSTABILITY. WITHOUT THE WEAK INSTABILITY, SATURATION LOOKS TO
OCCUR BELOW THE DGZ SO RAINFALL WOULD NOT BE EXPECTED WITHOUT THE
INSTABILITY. OVERALL IMPACTS WILL BE VERY MINOR.
UPPER LEVEL RIDGING BUILDS INTO THE AREA SUNDAY INTO MONDAY AHEAD OF
THE NEXT WAVE. THIS WAVE WILL BRING SMALL CHANCES FOR SHOWERS MONDAY
NIGHT INTO TUESDAY, BUT AGAIN VERY LOW CONFIDENCE FIGHTING DRIER AIR
WITH THE WAVE WELL TO THE NORTH. ONE THING THAT THIS WAVE WILL BRING
IS MILD WEATHER TO THE AREA. LOOKING AT HIGHS TUESDAY AND WEDNESDAY
AROUND 70 IN MOST LOCATIONS. HIGHS MORE IN THE LOWER TO MID 60S ARE
EXPECTED THIS WEEKEND.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 1107 PM CDT WED SEP 30 2026
RAIN OVER NORTHWESTERN IOWA, FAR NORTHEAST NEBRASKA, AND FAR
SOUTHEAST SOUTH DAKOTA WILL CONTINUE TO SLIDE EASTWARD THROUGH THE
REMAINDER OF THE NIGHT, ENDING FROM WEST TO EAST THURSDAY MORNING.
PATCHY FOG ALSO REMAINS POSSIBLE MAINLY OVER NORTHWEST IOWA (40%
CHANCE) THROUGH ABOUT SUNRISE. ANY DENSE FOG SHOULD REMAIN HIGHLY
LOCALIZED. AFTER THE RAIN AND ANY FOG EARLY THIS MORNING, VFR
CONDITIONS ARE EXPECTED THROUGH THE REMAINDER OF THE PERIOD.
WINDS WILL GRADUALLY INCREASE OUT OF THE NORTH-NORTHEAST
THROUGH THE MORNING HOURS TODAY, WITH A FEW GUSTS TO AROUND 20
TO LOCALLY 25 KTS DURING THE DAYTIME HOURS. WINDS WILL DIMINISH
THROUGH THE LATE AFTERNOON AND EVENING THURSDAY.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...SAMET
DISCUSSION...08
AVIATION...SAMET
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