textproduct: La Crosse

KEY MESSAGES

- Light snow is likely (70-90%) this morning into the early afternoon hours, primarily south of I-94. Accumulations around 0.5-1 inch are expected.

- Cold air moves in tonight, resulting in a cold start to the new year. Wind chills 10 to 20 degrees below zero are expected tonight into the morning of New Year's Day. High temperatures top out in the teens New Year's Day.

- Drier conditions and near to slightly above normal temperatures are expected for the beginning of the new year.

DISCUSSION

Issued at 356 AM CST Wed Dec 31 2025

Light Snow Today

A cold front, currently situated over northern Minnesota, will sink southward into the Upper Mississippi River Valley this morning supported by upper level troughing located over the Great Lakes region. Low level forcing along the front combined with 0-1km lapse rates steepening to 6-7 C/km in the cold air advection, and 700-800hPa frontogenesis are expected to provide enough upward vertical motion within a saturating atmosphere to support southeastward moving light snowfall into the afternoon (70-90%). There is some uncertainty in where the axis of highest snowfall will ultimately set-up given slight latitudinal variations among the high resolution guidance, but the majority of the 30.12z LREF membership (60-80%) highlights areas generally along a line from the Twin Cities to southwest Wisconsin as the most favorable to see snowfall today.

Snowfall amounts will be light as the 31.00z HREF LPMM depicts 24 hour QPF around 0.05 inches across our area, equating to accumulations of around 0.5"-1" when adjusted for expected snow-liquid ratios of 12-18:1. Can't completely rule out some flurries in the wake of the primary snowfall given the steepened low level lapse rates, although saturation will be shallow at best, limiting confidence to 10-30%.

Cold Temperatures Tonight into New Year's Day

Falling temperatures are expected overnight into the morning of New Year's Day as cold air advances into the region under northwesterly flow. Drier air also moves into the region, which should lead to at least a few hours of clearing skies overnight, allowing for a period of efficient radiational cooling. As such, have trended temperatures towards the 25th percentile of the 31.01z NBM but if skies clear earlier than expected, temperatures may fall further than currently forecast.

As it stands now, temperatures are expected to be in the single digits above and below zero to ring in the new year, coldest over central to north-central Wisconsin. Given the cold temperatures, wind chills of 10 to 20 degrees below zero are possible, so ensure you're dressed appropriately if venturing outside for New Year's Eve celebrations tonight.

Drier and Near to Slightly Above Normal Temperatures

Longwave ridging builds into the United States over the next several days, resulting in overall drier conditions and warming temperatures across the Upper Midwest. There remains the low potential (10-30%) of some light snow along and north of I-94 during the afternoon and evening of New Year's Day associated with a weak ripple in the northwest flow aloft, but as the ridge becomes more dominant over the course of the coming days, impactful weather becomes less probable with near to slightly above normal temperatures expected.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 600 AM CST Wed Dec 31 2025

MVFR to IFR conditions are expected to persist through much of the TAF period as another quick-moving system is progged to move through the region this morning. Light snow will move in around or slightly after daybreak from the north, bringing a period of low-end MVFR ceilings and IFR visibilities. Expect a period of gusty winds as a cold front swings through with these snow showers. Expect light snow to continue into the afternoon, before skies begin to scatter out and VFR conditions return by the evening.

ARX WATCHES/WARNINGS/ADVISORIES

WI...None. MN...None. IA...None.