textproduct: Sioux Falls

KEY MESSAGES

- Bitterly cold wind chills (as low as -20 to -30F) through mid-morning, with slow recovery through the day. Wind chills will remain sub-zero east of Huron-Mitchell-Sioux City today.

- Increasing south winds today will result in drifting of the fresh powdery snow. Watch for possible melt-refreeze as sun warms paved surfaces this afternoon. Enhanced southwest flow along/east of the Buffalo Ridge in southwest Minnesota tonight may locally reduce visibility in blowing snow as winds gusts over 40 mph.

- Quieter conditions with mild temperatures Monday-Wednesday, though fresh snowpack may impact how quickly temperatures warm.

- Wednesday night into Thursday will be the next system with the potential for impacts across the area. More of a wind threat than precipitation threat but if any snow can fall with the cold surge, blowing snow will be possible.

DISCUSSION

Issued at 323 AM CST Sun Dec 14 2025

TODAY-TONIGHT: Early morning temperatures not falling off quite as much as anticipated in some areas, but this is partially due to a lingering northwest breeze of 8-13 MPH, so the net result is similar with scattered wind chill readings reaching advisory levels as of 2 AM. These areas east of I-29 should see winds decrease through the pre-dawn hours as a surface ridge slides east, while at the same time our western areas begin to see a modest southerly flow develop. Although advisory-level wind chills may not be widespread or persistent with winds becoming nearly calm at times, will maintain Cold Weather Advisory through mid-morning.

Southerly flow will continue to increase after daybreak as the surface ridge slides east, becoming breezy to windy with gusts this afternoon from around 20 mph in northwest Iowa to 35 mph from south central to east central South Dakota and into parts of the higher elevations along the Buffalo Ridge. Some concern in locations which received greater amounts of powdery snow on Saturday, especially near/southwest of the James River Valley where temperatures have the best chance of climbing into the 20s this afternoon. This along with mostly sunny skies may warm pavement enough to slightly melt drifting snow, but not enough to keep it wet. Instead, the melted drifting snow refreezes and could cause slick driving conditions. Will highlight potential for this in our messaging this morning and monitor conditions through the day.

Very sharp surface-based inversion develops this afternoon and tonight in response to strong warm advection atop our fresh snowpack. Winds will generally ease a bit from afternoon peaks, but locations along and east of the Buffalo Ridge may see wind directions at a favored angle to produce enhanced winds on the downslope side of the ridge. HREF probabilities show high (>80%) chance for gusts exceeding advisory criteria in portions of Lincoln/Lyon/Murray/Cottonwood counties for a few hours this evening, but this broad of an area seems a bit overdone. Instead have blended wind and gusts from ARW/RAP to boost the NBM in a narrow area just east of the ridge peak, more similar to the higher probabilities seen in the REFS. Thankfully this area received little new snow with our most recent event, but may still be enough loose snow to produce localized visibility reductions in blowing snow. The southwest flow and associated strong warm advection late today/tonight will likely lead to a non-diurnal temperature trend with readings slowly warming through tonight.

MONDAY-WEDNESDAY: The first half of the work week will be dominated by a milder pattern, with temperatures above the surface warming well above freezing. The question is how much of this warmer air will translate to the surface given initial warming will work toward melting the modest snowpack across the region. Given this uncertainty, did not deviate from the NBM which brings most locations near to above freezing Monday, with more widespread upper 30s and 40s for highs Tuesday-Wednesday. A weak wave does slide across the northern Plains Monday night into Tuesday, but a deep layer of dry air in the lower-mid levels should limit precipitation potential.

WEDNESDAY NIGHT-THURSDAY: A sharper wave and associated strong push of cold air moves across the region mid-week. Differences in track lead to lower confidence in precipitation chances with the passing wave, though broad consensus will bring a chance of mainly light rain with the warm advection ahead of the wave on Wednesday. Trailing chances for light snow or persistent flurry activity in the cold trailing stratus may be more expansive than currently indicated by the NBM, but confidence is too low to adjust pops at this range.

Barring that, the main impacts from this clipper will be another round of non-diurnal temps and increasing northwest winds behind the cold front. Deterministic models showing good agreement in a surge of 50+kt winds at 850mb with the cold advection Thursday morning. Current NBM 90th percentile winds also indicate at least a low (10-30%) potential for widespread advisory-level wind gusts of 45-55 mph. If snow chances do increase behind the front, these gusts coinciding with falling snow could produce more widespread concerns from blowing snow, so this potential will need to be monitored in the coming days.

FRIDAY-SATURDAY: The latter part of the week currently looks less active with additional waves tracking north of our area. Temperatures remain on the mild side, though exact values are low confidence given timing differences of the aforementioned waves.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 545 AM CST Sun Dec 14 2025

VFR conditions will prevail at TAF sites and most locations through this period. However, early morning satellite indicates a small area of lower ceilings (unknown height due to lack of observations) near to just north of the Missouri River in south central South Dakota.

Greater aviation impact this period will come from increasing south to southwest winds. Occasional gusts 20-30kt develop by late morning into this evening, with stronger winds above a sharp inversion leading to areas of low level wind shear after sunset (mainly near/east of I-29). The gusty winds may result in areas of drifting snow, but visibility restrictions from lofted blowing snow are not anticipated for most areas. Exception will be near/east of the Buffalo Ridge in southwest Minnesota after sunset as a narrow corridor of enhanced downslope winds could gust in excess of 40kt for a few hours this evening.

FSD WATCHES/WARNINGS/ADVISORIES

SD...Cold Weather Advisory until 10 AM CST this morning for SDZ038>040-053>056-059>062-065>067. MN...Cold Weather Advisory until 10 AM CST this morning for MNZ071- 072-080-081-089-090-097-098. IA...Cold Weather Advisory until 10 AM CST this morning for IAZ001>003-012>014-021-022-032. NE...None.