textproduct: Sioux Falls

KEY MESSAGES

- Widespread stratus continues today. Fog, including patchy dense fog, continues this morning. Additional fog may develop again tonight. Isolated slick spots are possible with temperatures below freezing.

- Minimal (less than 15%) risk for light wintry precipitation develop along the Buffalo Ridge briefly today with no accumulation expected.

- A warm and mostly quiet forecast persists much of this week. Outside of minimal (less than 20%) precipitation risks Monday night into Tuesday evening, the next possibly more widespread risk won't be until the end of the week.

DISCUSSION

Issued at 301 AM CST Sun Jan 4 2026

THROUGH TONIGHT: Fog has continued to expand over the area this morning. At the time of this discussion, dense fog with visibility at or below one half of a mile remains fairly scattered. Will continue to monitor trends for potential Dense Fog Advisory issuance this morning. Isolated slick spots are possible through the morning hours with temperatures at or below freezing.

As mentioned in the previous discussion, soundings continue to show a lack of top-down saturation with the WAA; however, can't entirely rule out some very light and isolated wintry precipitation along the Buffalo Ridge through today. No accumulations nor impacts expected.

Some minor uncertainty regarding just how warm we'll get today due to stratus. However, WAA and a shift to southerly flow behind a surface warm front should allow most of the area to warm into the 40s, with 50s across south central SD where sun is more likely much of the day. Breezy today with a compressed surface pressure gradient as surface low pressure moves across the area tonight. Southerly winds may gust to 30 mph this afternoon and early evening. This along with warmer temperatures could lead to some localized areas of slightly elevated fire danger across south central SD this afternoon.

Warmer again tonight with lows in the 20s to mid 30s - closer to average highs than lows for this time of year. May see some wrap around stratus along and east of the I-29 corridor as low pressure moves east. Fog, including locally dense, may also return to the area late tonight into Monday morning.

MONDAY-TUESDAY: Ridging builds for the early part of the work week, with a couple quick moving waves trekking through the Plains - one Monday night into Tuesday and the second Tuesday evening. This may again bring some light mixed precipitation to portions of the area, focused along and north of US Hwy 14 into southwestern MN. Ensemble guidance shows low to moderate (less than 40%) chance for more than 0.01" of liquid into Tuesday evening. Have left the NBM for now given timing and saturation differences in the waves, but any precipitation or accumulations are expected to remain light at this time. Temperatures remain above normal, with Tuesday slightly cooler behind a cold front. Highs in the upper 30s to mid 50s.

WEDNESDAY ONWARD: Westerly flow aloft expected mid week, with troughing developing over the Rockies by Thursday. Above average temperatures continue. Guidance is coming into more agreement with the timing of the trough ejection Friday; however, guidance remains quite variable on the details including orientation and strength of the main trough, exact timing, and any preceding waves Thursday. For now, average 04.00z ensemble guidance shows 24 hr probability of more than 0.01" or precip to be low to moderate (around or less than 60%), although these values are slightly higher for the ECMWF ensemble. This is a time to keep an eye, especially if you have regional travel plans late this week. Temperatures do look to return closer to seasonal averages to start next weekend.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 532 AM CST Sun Jan 4 2026

IFR to LIFR fog and stratus continues this morning, with some clearing beginning in the southern MO River Valley as southeasterly winds increase. Have seen visibility for some locations below 1/2 SM. Conditions should improve back to VFR this afternoon and into the evening although kept some SCT stratus around the area. Fog and stratus should return tonight, especially east of the James River, which will lead to MVFR and possibly IFR conditions once again.

Winds today will be southerly for most of the day with gusts around 25 knots. Expect winds to taper down this evening, becoming light and more variable in direction.

FSD WATCHES/WARNINGS/ADVISORIES

SD...Dense Fog Advisory until noon CST today for SDZ038-050-052-053- 057>060-063>065-068-069. MN...None. IA...None. NE...None.