596
FXUS63 KFSD 240937
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
337 AM CST WED DEC 24 2025
KEY MESSAGES
- GROWING POTENTIAL FOR AREAS OF FOG AND DRIZZLE TODAY THROUGH
CHRISTMAS DAY, MAINLY ALONG/EAST OF MN/IA HIGHWAY 60 TODAY,
THEN EXPANDING AS FAR WEST AS I-29 TONIGHT INTO THURSDAY. A
LIGHT GLAZE OF ICE IS POSSIBLE NEAR TO NORTH OF I-90 TONIGHT
INTO CHRISTMAS MORNING AS TEMPERATURES FALL BELOW 32F.
- TEMPERATURES REMAIN ABOVE NORMAL THROUGH THE END OF THIS
WEEK, BUT WE TURN WINDY AND COLDER THIS WEEKEND, WITH WIND
CHILLS LIKELY DROPPING BELOW ZERO BY SUNDAY MORNING.
- PRECIPITATION CHANCES FRIDAY-SATURDAY ARE LOW, BUT MAY HAVE
TO WATCH FOR SCATTERED FLURRIES SUNDAY AS COLDER AIR MOVES IN.
- ELEVATED FIRE DANGER WILL BE POSSIBLE ON BREEZIER DAYS IN
SNOW- FREE AREAS, MAINLY ACROSS SOUTH CENTRAL SOUTH DAKOTA
THROUGH THE MISSOURI RIVER VALLEY.
DISCUSSION
ISSUED AT 335 AM CST WED DEC 24 2025
MAIN FOCUS FOR THIS FORECAST PERIOD WILL BE FOCUSED ON TODAY INTO
CHRISTMAS DAY, WHICH HAS TURNED A BIT MORE CHALLENGING DUE TO A
GROWING POTENTIAL FOR FOG AND DRIZZLE. INCREASING LOW LEVEL MOISTURE
LOOKS TO BECOME TRAPPED BENEATH A STRONG TEMPERATURE INVERSION,
MAINLY IN OUR EASTERN COUNTIES TODAY AHEAD OF A SUBTLE BOUNDARY
WHICH MOVES EAST TOWARD THE MN/IA HIGHWAY 60 CORRIDOR BY SUNSET. THE
MORE ABUNDANT LOW LEVEL MOISTURE IS ALREADY PRESENT IN OUR FAR EAST
WHERE WE HAVE SOME DENSE FOG EARLY THIS MORNING. THE DENSE FOG
ADVISORY HAS BEEN EXTENDED THROUGH 8 AM CST, BUT WEAK MIXING AHEAD
OF THE BOUNDARY SHOULD ALLOW THIS FOG TO LIFT A BIT AFTER SUNRISE.
INCREASING MOISTURE ADVECTION IN A SOUTHERLY FLOW BENEATH THE
CONTINUED WARM ADVECTION ALOFT, COMBINED WITH ADDITIONAL SNOW MELT
MOISTURE FROM OUR REMAINING DEEPER SNOW-PACK IN NORTHWEST IOWA, WILL
SERVE TO REINFORCE THIS LOW LEVEL MOISTURE THROUGH THE AFTERNOON,
WHICH IS THEN EXPECTED TO EXPAND TOWARD I-29 AND PERHAPS BEYOND
TONIGHT IN A PREVAILING EASTERLY FLOW. AREAS OF DENSE FOG COULD
AGAIN DEVELOP TONIGHT INTO CHRISTMAS MORNING, THOUGH THIS IS A LOWER
CONFIDENCE FORECAST THAN THE MORE GENERAL FOG/STRATUS WHICH IS
EXPECTED.
ALSO A LOWER CONFIDENCE FORECAST IS THE POTENTIAL FOR DRIZZLE,
MAINLY DUE TO UNCERTAINTY IN THE THICKNESS/DEPTH OF THE LOW LEVEL
MOIST LAYER. HOWEVER, SEVERAL CAMS SHOW SPOTTY LIGHT QPF THIS
AFTERNOON THROUGH CHRISTMAS DAY WITH FORECAST SOUNDINGS SUPPORTING A
MOIST LAYER DEPTH APPROACHING 1KM. AS SUCH, FELT IT PRUDENT TO
INTRODUCE SOME LOW POPS AND DRIZZLE MENTION GIVEN POTENTIAL IMPACTS
ON HOLIDAY TRAVELERS. THIS IS ESPECIALLY A CONCERN BY LATE EVENING
THROUGH MIDDAY CHRISTMAS DAY WHEN AREAS NEAR TO NORTH OF I-90 SHOULD
SEE AIR TEMPERATURES DROP TO NEAR OR BELOW FREEZING. AS WE SAW WITH
OUR LIGHT RAIN EVENT EARLIER THIS WEEK, EVEN IF AIR TEMPERATURES ARE
JUST ABOVE FREEZING, ROAD SURFACE TEMPERATURES COULD STILL BE COLD
ENOUGH TO ALLOW FOR LIGHT ICING. THOSE WITH TRAVEL PLANS TONIGHT
INTO CHRISTMAS DAY WILL WANT TO MONITOR WEATHER AND ROAD CONDITIONS
BEFORE HEADING OUT, ESPECIALLY IF HEADING NORTH WHERE SUB-FREEZING
TEMPERATURES ARE MORE LIKELY.
THIS MOISTURE SHOULD SLOWLY BE SCOURED OUT WEST TO EAST THURSDAY
NIGHT AS ANOTHER WEAK BOUNDARY AND ASSOCIATED MID-LEVEL WAVE MOVE
EAST ACROSS THE DAKOTAS/MINNESOTA. UNLIKE TODAY AND CHRISTMAS DAY
WHICH HAVE TRENDED COOLER OVER THE PAST SEVERAL DAYS, FORECAST
TEMPERATURES FOR FRIDAY AND SATURDAY ARE TRENDING UPWARD WITH
HIGHS IN THE 40S AND 50S.
THIS IS AHEAD OF A VERY STRONG COLD FRONT AND ITS ASSOCIATED
UPPER TROUGH WHICH PUSHES ACROSS THE REGION SATURDAY NIGHT.
POST-FRONTAL NORTHWEST WINDS WILL BECOME GUSTY, BUT NOT AS
STRONG AS WE HAVE SEEN WITH THE PAST COUPLE OF POTENT COLD
FRONTS. SOUNDINGS SUGGEST WINDS AT THE TOP OF THE MIXED LAYER
ARE IN THE 40-45KT RANGE, WHICH COULD SUPPORT ISOLATED ADVISORY
LEVEL WINDS. NIGHTTIME TEMPERATURES FALL BACK INTO THE TEENS
AND SINGLE DIGITS EARLY NEXT WEEK, WITH GUSTY NORTHWEST WINDS
PUSHING WIND CHILLS INTO THE SINGLE DIGITS AND TEENS BELOW ZERO.
TEMPERATURES ONLY RECOVER INTO THE TEENS/20S FOR HIGHS SUNDAY
AND MONDAY, AND IF WE HAVE ANY STRATOCU DEVELOPMENT, 925MB
TEMPERATURES OF -10 TO -18C COULD SUPPORT SCATTERED FLURRIES.
THIS COOLDOWN LOOKS TO BE RATHER SHORT-LIVED, THOUGH, WITH
WARMER AIR RETURNING TO THE FORECAST AREA BY THE MIDDLE OF
NEXT WEEK.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 1030 PM CST TUE DEC 23 2025
MOSTLY VFR WITH OCCASIONAL IFR TO LIFR VSBY AND CIGS ARE
EXPECTED THIS TAF PERIOD. TAKING A LOOK AT SATELLITE IMAGERY,
HIGH LEVEL CIRRUS CONTINUES TO SIT OVER THE AREA WITH A MORE
CONCENTRATED AREA OF LOW-LEVEL STRATUS/DEVELOPING FOG SITTING
OVER PORTIONS OF SOUTHWESTERN MN AND NORTHWESTERN IA. WHILE THE
DEVELOPING AREAS OF FOG COULD LEAD TO PERIODS OF IFR TO LIFR
VSBYS AND CIGS, SHOULD SEE COVERAGE GRADUALLY SHRINK BY MID-
MORNING. FROM HERE, AREAS OF STRATUS AND/OR FOG WILL REDEVELOP
DURING THE AFTERNOON HOURS ON WEDNESDAY MAINLY ACROSS NORTHWESTERN
IA INITIALLY THEN BECOMING MORE WIDESPREAD OVERNIGHT. LASTLY,
SOUTHERLY WINDS THROUGH THE DAY ON WEDNESDAY WILL BECOME MORE
LIGHT AND VARIABLE BY WEDNESDAY NIGHT.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...DENSE FOG ADVISORY UNTIL 8 AM CST THIS MORNING FOR MNZ080-081-
090.
IA...DENSE FOG ADVISORY UNTIL 8 AM CST THIS MORNING FOR IAZ003.
NE...NONE.
DISCUSSION...JH
AVIATION...05
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