163
FXUS63 KFSD 241145
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
545 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 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 /12Z TAFS THROUGH 12Z THURSDAY/
ISSUED AT 545 AM CST WED DEC 24 2025
MVFR CONDITIONS OVER PORTIONS OF NORTHWEST IOWA AND SOUTHWEST
MINNESOTA AS WE START THIS TAF PERIOD DUE TO AREAS OF FOG ALONG
THE HIGHWAY 71 CORRIDOR AND AN AREA OF STRATUS MOVING NORTH
THROUGH EASTERN NEBRASKA/WESTERN IOWA. CONDITIONS MAY BRIEFLY
IMPROVE DURING THE LATE MORNING-AFTERNOON, BUT OVERALL EXPECT
CONDITIONS TO DETERIORATE OVER MUCH OF THE AREA TONIGHT AS FOG
AND STRATUS EXPAND WESTWARD.
COULD ALSO SEE AREAS OF DRIZZLE DEVELOP WITHIN THE THICKER
STRATUS ALONG/EAST OF I-29, INCLUDING KFSD/KSUX. TEMPERATURES
ARE EXPECTED TO FALL BELOW FREEZING NORTH OF I-90, AND POSSIBLY
ALONG THE I-90 CORRIDOR, RESULTING IN A POTENTIAL FOR -FZDZ FOR
SOUTHWEST MINNESOTA AND THE I-29 CORRIDOR NORTH OF KFSD. A LOW
PROBABILITY THAT -FZDZ COULD BRIEFLY OCCUR AT KFSD TOWARD THE
END OF THIS PERIOD, BUT CONFIDENCE IS TOO LOW TO INCLUDE.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...JH
AVIATION...JH
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