058
FXUS63 KFSD 260445
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1045 PM CST THU DEC 25 2025
KEY MESSAGES
- DENSE FOG WITH VISIBILITY 1/2 MILE OR LESS IS EXPECTED TO
ONLY SLOWLY IMPROVE THROUGH THE NIGHT AND THE DENSE FOG MAY
LINGER INTO FRIDAY MORNING WITH THE HIGHEST CHANCE FOR THIS
OCCURRING NEAR AND EAST OF I-29.
- ABOVE NORMAL TEMPERATURES THROUGH SATURDAY TURN SHARPLY
COLDER SUNDAY ACCOMPANIED BY NORTHWEST WINDS GUSTING 30 TO 45
MPH. SUB-ZERO WIND CHILLS ARE EXPECTED SUNDAY NIGHT-EARLY
MONDAY.
- AREAS OF LIGHT SNOW OR FLURRIES COULD ACCOMPANY THE COLDER
AIR ON SUNDAY. LIGHT SNOW ACCUMULATIONS ARE POSSIBLE, WITH
AREAS OF BLOWING SNOW IF ACCUMULATIONS APPROACH AN INCH OR
MORE.
UPDATE
ISSUED AT 1038 PM CST THU DEC 25 2025
DENSE FOG HAS EXPANDED INTO THE JAMES RIVER VALLEY, SO ADDED A
COUPLE OF WESTERN TIERS OF COUNTIES TO THE DENSE FOG ADVISORY.
MAINTAINED THE END TIME OF 9 AM CST; HOWEVER, GUIDANCE CONTINUES
TO TREND SLOWER WITH ANY IMPROVEMENTS IN FOG/STRATUS, SO THIS
MAY NEED TO BE EXTENDED IN TIME IF TRENDS CONTINUE.
DISCUSSION
ISSUED AT 211 PM CST THU DEC 25 2025
A QUICK MOVING WAVE WILL BRING VERY SPOTTY, LIGHT PRECIPITATION THIS
AFTERNOON INTO TONIGHT WITH LITTLE TO NO IMPACTS, BUT THIS WAVE WILL
SWING THROUGH A WEAK COLD FRONT. THE LATEST MODEL SOUNDINGS ARE
PRETTY PESSIMISTIC ABOUT SCOURING OUT THE STRATUS AND FOG WITH THIS
BOUNDARY, SO WENT AHEAD AND EXTENDED THE DENSE FOG ADVISORY THROUGH
FRIDAY MORNING FOR MOST LOCATIONS EAST OF THE JAMES RIVER. AREAS
NEAR AND EVEN WEST OF THE JAMES RIVER MAY NEED TO BE INCLUDED IN
THIS ADVISORY IF CONFIDENCE IN CREASES AS THE DRY PUNCH WITH THIS
BOUNDARY IS NOT EXPECTED TO BE VERY STRONG. WINDS WILL QUICKLY TURN
BACK TO THE SOUTH ON FRIDAY AFTERNOON, ALBEIT NOT VERY STRONGLY.
THIS WILL LEAD TO A MILD WINTER DAY, LIKELY STILL FIGHTING SOME
STRATUS AND FOG CONCERNS.
FRIDAY NIGHT INTO SATURDAY SHOWS POTENTIAL TO BE VERY MILD, HOWEVER
TEMPERATURES ALOFT WARM A DECENT AMOUNT FRIDAY NIGHT AND WE COULD
SEE SOME FOG AND STRATUS CHALLENGES AGAIN, WHICH OF COURSE IF THEY
LINGER INTO THE DAY SATURDAY WOULD LIMIT ANY DAYTIME RISE IN
TEMPERATURES. FOR NOW THINKING 50S IN MANY LOCATIONS, WITH THE
BETTER CHANCES NEAR THE MISSOURI RIVER.
A STRONGER WAVE DIGS INTO THE AREA SATURDAY NIGHT INTO SUNDAY AND IF
THERE IS ANY FOG AND STRATUS LEFT, IT WILL ERODE QUICKLY THROUGH
SUNDAY MORNING AS COLDER AND DRIER AIR BUILDS SOUTH. THERE WILL BE A
CHANCE FOR SOME LIGHT SNOW SUNDAY BUT SOME OF THE MODEL SOUNDINGS
INDICATING A BIT OF A DRY WEDGE FROM AROUND 900MB TO 700MB WHICH
WOULD LIMIT PRECIPITATION PRODUCTION AT THE SURFACE SO FOR NOW ONLY
A VERY LOW CHANCE FOR IMPACTFUL SNOWFALL ON SUNDAY. THE LATEST GEFS
AND EC AI BRINGING ABOUT A 20-30 PERCENT CHANCE FOR AN INCH OF SNOW
WHILE THE EC ENSEMBLE IS LESS THAN 10 PERCENT.
COLD HIGH PRESSURE BUILDS SOUTH SUNDAY NIGHT INTO MONDAY BRING BELOW
NORMAL TEMPERATURES FOR BOTH SUNDAY AND MONDAY. WITHOUT MUCH SNOW
LEFT ON THE GROUND TEMPERATURES WILL BE LIMITED ON HOW COLD THEY
WILL GET.
TUESDAY INTO THURSDAY APPEARS TO KEEP MAINLY DRY CONDITIONS IN PLACE
WITH STRONG NORTHWEST FLOW ALOFT. TEMPERATURES TUESDAY LIKELY TO BE
ABOVE NORMAL, THEN COOLER AIR MAY SETTLE SOUTH AND DROP TEMPERATURES
BELOW NORMAL, BUT CONFIDENCE ON THIS IS A BIT LOW WITH SOME
DISAGREEMENT ON THE STRENGTH OF THE COLD AIR AS WELL AS THE
OCCASIONAL LOWER PREDICTABILITY OF THESE WEAKER WAVES IN NORTHWEST
FLOW.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1038 PM CST THU DEC 25 2025
IFR TO LIFR STRATUS AND FOG CONTINUE FOR NEARLY THE ENTIRE AREA
THROUGH AT EAST FRIDAY MORNING. GUIDANCE CONTINUES TO TREND
SLOWER WITH ANY IMPROVEMENT, SO MAY SEE THIS LINGER INTO THE
EARLY TO MID AFTERNOON HOURS. CONFIDENCE IS LOW ON THE TIMING
AND DURATION OF A RETURN TO MVFR OR VFR CONDITIONS FRIDAY. FOG
LOOKS TO DEVELOP AGAIN TOWARD THE END OF THE PERIOD ALONG AND
EAST OF I-29.
WINDS BECOME LIGHT AND REMAIN SO THROUGH FRIDAY EVENING.
DIRECTION WILL BE VARIABLE, TURNING NORTHWESTERLY TONIGHT AND
FRIDAY MORNING BEFORE SWITCHING TO SOUTHERLY TO END THE PERIOD.
FSD WATCHES/WARNINGS/ADVISORIES
SD...DENSE FOG ADVISORY UNTIL 9 AM CST FRIDAY FOR SDZ038>040-
053>056-059>062-065>067-069>071.
MN...DENSE FOG ADVISORY UNTIL 9 AM CST FRIDAY FOR MNZ071-072-080-
081-089-090-097-098.
IA...DENSE FOG ADVISORY UNTIL 9 AM CST FRIDAY FOR IAZ001>003-
012>014-020>022-031-032.
NE...DENSE FOG ADVISORY UNTIL 9 AM CST FRIDAY FOR NEZ013-014.
UPDATE...SG
DISCUSSION...08
AVIATION...SG
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