300
FXUS63 KFSD 050449
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1049 PM CST SUN JAN 4 2026
KEY MESSAGES
- LOW STRATUS AND FOG RETURNS INTO MONDAY MORNING, MOSTLY ALONG
AND EAST OF THE JAMES RIVER. AT TIMES, DENSE FOG MAY BE
POSSIBLE.
- A WARM AND MOSTLY QUIET FORECAST PERSISTS THROUGH THURSDAY.
OUTSIDE OF MINIMAL (LESS THAN 20%) PRECIPITATION RISKS MONDAY
NIGHT INTO TUESDAY EVENING.
- A GREAT DEAL OF UNCERTAINTY CONTINUES IN THE POTENTIAL FOR
ANOTHER STORM SYSTEM ARRIVING FRIDAY INTO SATURDAY, WITH
PROBABILITIES FOR MEASURABLE WINTRY PRECIPITATION REMAINING
AROUND 30%.
DISCUSSION
ISSUED AT 149 PM CST SUN JAN 4 2026
THIS AFTERNOON: MID-LVL TROUGH CROSSING THE DAKOTAS THIS AFTERNOON
CONTINUES TO PUSH WARMER AIR EASTWARD. AT THE SURFACE AN AREA OF
LOW PRESSURE HAS DEVELOPED OVER THE NORTHEASTERN PORTIONS OF SOUTH
DAKOTA, WITH A TRAILING COLD FRONT SWEEPING INTO THE JAMES RIVER
VALLEY AS OF 1PM. AS SHORTWAVE ENERGY BEGINS TO MOVE INTO MINNESOTA
LATE THIS AFTERNOON, WE'LL CONTINUE TO SEE THAT AFOREMENTIONED
COLD FRONT SLIDE SOUTHEAST PUSHING A NARROW CORRIDOR OF UPPER
40S AND 50S AHEAD OF IT. WE'LL ALSO BEGIN TO SEE STRATUS RETURN
AND SLIP SOUTHEAST ALONG HIGHWAY 14 BY SUNSET.
TONIGHT: MOST GUIDANCE IS IN GOOD AGREEMENT THAT AS LOW LEVEL FLOW
TURNS MORE TO THE NORTHWEST, STRATUS WILL BUILD SOUTHEAST ALONG THE
COTEAU DES PRAIRIES. GIVEN THE WEAK SURFACE FLOW, AREAS OF FOG
AND EVEN DENSE FOG WILL FORM. CURRENTLY, HIGHEST PROBABILITIES
FOR DENSE FOG RESIDE EAST OF THE JAMES RIVER VALLEY. DEPENDING
ON THE COVERAGE OF DENSE FOG, ADVISORIES MAY BE NEEDED INTO
MONDAY.
MONDAY: STRATUS AND FOG MAY BE SLOW TO ERODE UNTIL LOW-LVL
WINDS BEGIN TO SHIFT BACK TO THE SOUTHWEST BY MID-MORNING. WITH
SURFACE WINDS TURNING SOUTHERLY THROUGH THE DAY, AND A
CONSIDERABLE AMOUNT OF LOW-LVL WARM AIR ADVECTING OVERHEAD, WE
SHOULD AGAIN SEE HIGHS IN THE 40S MOST EVERYWHERE WITH 50S
ALONG THE MO RIVER VALLEY. MID-LVL CLOUDS WILL ALSO BE ON THE
INCREASE THROUGH THE DAY.
TUESDAY: MID-LVL VORTICITY WILL CONTINUE TO STREAM THROUGH THE
REGION MONDAY NIGHT INTO TUESDAY. QUESTIONS REMAIN ON OVERALL COLUMN
SATURATION OVERNIGHT AND INTO TUESDAY, SO ANY QPF IS ANTICIPATED TO
STAY ON THE VERY LIGHT SIDE THROUGH TUESDAY. TEMPERATURES MAY ALSO
STAY NEAR OR ABOVE FREEZING THROUGH TUESDAY, LIKELY MEANING THAT
MOST PRECIPITATION WILL JUST FALL AS A COLD RAIN/SPRINKLE/FLURRY.
WEDNESDAY-THURSDAY: QUASI-ZONAL FLOW ON WEDNESDAY WILL GRADUALLY
BEGIN TO SHIFT MORE TO THE SOUTHWEST BY THURSDAY AS TROUGHING ENTERS
THE WEST COAST. SOUTHWESTERLY SURFACE WINDS WILL LEAD TO A VERY
PLEASANT DAY ON WEDNESDAY WITH HIGHS NEARING THE 50S. ONLY A SLIGHT
COOLDOWN IS EXPECTED THURSDAY AS A WEAK LOW-LVL COOL FRONT DROPS IN
FROM THE NORTHWEST.
FRIDAY-SATURDAY: WE'RE STILL WATCHING THE POTENTIAL RETURN OF A
WINTRY MIX OF PRECIPITATION TO END THE WORK WEEK. A LARGE SPREAD IN
DETERMINISTIC AND ENSEMBLE GUIDANCE CONTINUES TODAY, MOSTLY DUE TO
THE INCONSISTENCIES IN GUIDANCE TO RESOLVE THE PHASING BETWEEN
TROUGHS CROSSING THE CONUS. THE GFS/CMC ARE MORE PHASED WITH A
DIGGING NORTHERN STREAM AND EASTWARD TRACKING SECONDARY TROUGH
CROSSING THE SOUTHWEST THURSDAY. THIS WOULD RESULT IN A DEEPER
DEVELOPING LOW OVER THE SOUTHERN PLAINS TO MID-MISSISSIPPI RIVER
VALLEY. MEANWHILE THE ECMWF/ECE SUPPORT LESS PHASING, A MORE
POSITIVELY TILTED NORTHERN STREAM TROUGH, STRONGER SOUTHEAST
RIDGING, ALLOWING THE SOUTHERN STREAM SYSTEM TO TRACK FURTHER NORTH
AND DEEPEN IN THE UPPER MIDWEST. ALL THAT TO SAY...FURTHER
FLUCTUATIONS IN GUIDANCE CAN BE EXPECTED AS BOTH OF THESE FEATURES
AND DRIVING JETS REMAIN OVER THE PACIFIC UNTIL WEDNESDAY.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1049 PM CST SUN JAN 4 2026
FOG HAS FINALLY DEVELOPED ACROSS THE AREA, GENERALLY ALONG AND NORTH
OF I-90. CHANCES FOR FOG AT KHON HAVE DWINDLED SO HAVE OMITTED FROM
ITS TAF. THE FOG WILL CONTINUE TO EXPAND TO THE SOUTH AND EAST
BEFORE DISSIPATING DURING THE MORNING HOURS. KFSD IS THE ONLY TAF
SITE THAT IS EXPECTED TO SEE FOG SO HAVE INCLUDED FOG FROM TONIGHT
INTO TOMORROW MORNING. ONCE THE FOG DISSIPATES BY TOMORROW MORNING,
A MOSTLY QUIET AFTERNOON IS IN STORE. THERE COULD BE SOME LIGHT
RAIN/FREEZING RAIN SHOWERS TOMORROW AFTERNOON AND EVENING ALONG
HIGHWAY-14, ESPECIALLY ALONG ITS SOUTHWEST MINNESOTA PORTION. AS OF
NOW, THESE SHOWERS ARE NOT EXPECTED TO AFFECT ANY TAF SITES. A
SECOND ROUND OF FOG IS POSSIBLE TOWARDS THE END OF THE TAF PERIOD.
CONFIDENCE IS NOT HIGH ENOUGH TO INCLUDE MENTION OF FOG IN A TAF AT
THIS TIME INTERVAL BUT TRENDS WILL BE MONITORED.
FSD WATCHES/WARNINGS/ADVISORIES
SD...DENSE FOG ADVISORY UNTIL 9 AM CST MONDAY FOR SDZ039-040-055-
056.
MN...DENSE FOG ADVISORY UNTIL 9 AM CST MONDAY FOR MNZ071-080-089-
097-098.
IA...NONE.
NE...NONE.
DISCUSSION...DUX
AVIATION...MEYERS
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