textproduct: La Crosse

KEY MESSAGES

- Multiple winter weather hazards expected this afternoon into Wednesday morning. Heavy snow expected north of I-94 where up to 6 inches of snow is possible within 4-6 hours under snowfall rates of 1-1.5 inches/hour. South and west of I-94, a corridor of light freezing rain is possible this evening across portions of SE MN, NE IA, and far SW WI before a transition to all rain occurs.

- Strong winds with gusts around 45 mph and additional accumulating snowfall are expected overnight into early Wednesday morning, primarily west of the Mississippi River.

- Temperatures begin to fall Wednesday through the rest of the week, with highs on Friday and Saturday struggling to climb out of the single digits. Wind chills of -25F or lower are possible (30-70%).

DISCUSSION

Issued at 212 PM CST Tue Dec 9 2025

This Afternoon and Evening

Messy winter weather this afternoon into this evening remains the primary focus of the forecast as a quick hitting dynamic system currently situated over the Dakotas moves southeastward into the region. Starting from the north, snow is expected to fall, primarily along and north of I-94, highest over Taylor and Clark counties where a band of 5-7 inches of snow is expected associated with 900-700hPa frontogenesis. Snowfall rates of 1-1.5 inches are possible per the 09.12z HREF which will lead to these accumulations over a short period, on the order of around 6 hours. A slight southward shift in the recent High-Resolution guidance brings some higher amounts towards the I-94 corridor which primarily affects the northern portions of Jackson, Juneau, and Adams counties.

Working south, light freezing rain has been observed in west-central Minnesota this afternoon which is expected to spread southeast into the region over the next few hours. 850hPa warm air advection continues, nudging temperatures above freezing over areas south and west of I-94 which is expected to be enough to warrant some freezing rain across portions of southeast Minnesota, northeast Iowa, and southwest Wisconsin this afternoon and evening. There is a question of how much dry air will be in place within this warm nose, but a saturated atmosphere above combined with strong forcing from the dynamic system should be able to overcome this. Overall, expecting generally a glaze to a 0.05" of ice accumulation over the aforementioned areas. As warm air advection continues under southerly flow, a transition to all rain is expected before colder air is ushered into the region, allowing for a transition to snow overnight.

Strong Winds and Additional Snowfall Overnight

The synoptic low level wind field increases drastically overnight for areas west of the Mississippi River into far southwestern Wisconsin as the pressure gradient associated with this winter system tightens in response to the low deepening over Minnesota/Wisconsin. As a result, surface winds increase overnight into Wednesday morning, with gusts of 40+ mph possible. 09.12z HREF probabilities are the highest with regard to wind gusts, suggesting 70-90% for gusts greater than 45 mph, only 10-20% in the 09.13z NBM. Confidence leans towards the stronger wind gust solution given steepening 0-2km lapse rates, nearly unidirectional wind profile, and observed winds over the northern Great Plains of 35-45mph. Despite this confidence, have opted to not issue a Wind Advisory this afternoon to avoid confusion with the ongoing Winter Weather Advisory across these areas.

Along with the strong winds, additional accumulating snowfall is expected overnight along the cold front, generally up to 1 inch and primarily along and north of I-90. The potential for intense bursts of snow has fallen off dramatically as low level lapse rates in the RAP/HRRR/NAM soundings have decreased in recent runs, limiting the convective nature of the snowfall. Still expecting difficult travel during this period given the strong winds and snowfall, but the intense bursts seem less likely than 24 hours ago.

Very Cold Temperatures Late This Week

Cold air moves into the region behind tonight's system under northwest flow, resulting in falling temperatures through the weekend. Temperatures are currently expected to bottom out Saturday and Saturday night when the 09.13z NBM mean suggests highs in the single digits above and below zero and overnight lows in the single to double digits below zero. Given there are still several days between now and the weekend, exact values are not certain. However, probabilities continue to suggest that very cold wind chills are possible Friday night and again Saturday night with the 09.00z LREF suggesting 30-60% and 50-70% probabilities for wind chills less than -25C, respectively.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1139 AM CST Tue Dec 9 2025

Messy aviation forecast over the next 12-24 hours is shaping up across the Upper Mississippi Valley. A deck of LIFR to MVFR stratus is currently situated over the area with a few breaks to allow for transient VFR conditions at times. Precipitation begins to move in later this afternoon from the northwest. Precipitation will likely start in the form of snow and freezing rain with a transition to rain/snow this evening. As cold air begins to move in on the back side of this system, precipitation will change over the snow overnight. CIGs and visibilities will likely remain in the MVFR to low end-IFR range (some high-end LIFR possible) for much of the period with slight improvement expected after 12Z. Winds are expected to pick up quite a bit overnight with some blowing snow potential, especially for areas along and west of the Mississippi (including the RST terminal). Wind gusts for the overnight time period will be in the 35-45 kt range west of the river with 25-35 kt gusts possible along and east of the river. Southerly winds at the start of the period will gradually veer to the west/northwest this evening and into the overnight period with speeds on the rise starting later this afternoon.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Winter Weather Advisory until 6 AM CST Wednesday for WIZ032>034-041>044-053>055-061. Winter Storm Warning until 6 AM CST Wednesday for WIZ017-029. MN...Winter Weather Advisory until 6 AM CST Wednesday for MNZ079- 086>088-094>096. IA...Winter Weather Advisory until 6 AM CST Wednesday for IAZ008>011-018-019-029-030.