textproduct: La Crosse

KEY MESSAGES

- Multiple periods of light snow begin this evening and last through the weekend. The greatest potential for accumulating snow will be tonight into Friday morning.

- Overall total snowfall amounts should be light--1 to 3 inches. However, a narrow corridor of 3-5 inches of snow could occur overnight. Confidence in this band even developing is low (10-20%) and could affect anywhere along and north of I-90.

- Increasing winds behind a cold front on Friday afternoon, coupled with bands of snow showers, could result in localized blowing snow and travel impacts west of the Mississippi River. Confidence in impacts remains on the lower side (20-40%) owing to unknowns in the exact placement of the showers and their strength.

- Temperatures plummet for the weekend with lows falling to the single digits below zero for Saturday night through at least Monday night. Morning wind chills fall to between -10 and -20.

DISCUSSION

Issued at 120 PM CST Thu Jan 15 2026

This Afternoon - Tonight: First Bands of Snow

The leading mid-tropospheric warm air advection/fgen wing of snow has been sliding ESE from north-central Minnesota and gradually filling in to the south through the day as it battles lower tropospheric dry air. This battle has resulted in a slower onset time to the snow than earlier forecast with light amounts (<0.5") confined to mainly along and east of the Mississippi River later this afternoon and evening.

As the dry slot cuts through behind this WAA wing this evening, still cannot fully rule out a period of freezing drizzle, but will hinge on how much the earlier band of snow can saturate the lower troposphere. Forecast profiles along and south of Highway 10 show an appreciable dry layer near the surface and thinner liquid cloud depths, which would limit the freezing drizzle risk. Therefore, have kept the wintry mix wording further north of this line.

The 850-mb trough digging southeastward overnight presents the best window of opportunity for accumulating snow for this drawn out event. Several runs of the HRRR/RAP over the last 12 hours have developed a meso-low at the base of this trough, resulting in enhanced snowfall rates near/north of this low. However, this has been a fleeting solution (10-20% confidence) and a sizable number of other runs/CAMs keep the wave open and snowfall amounts much less (1- 2").

The track of this meso low will also dictate snowfall amounts. Earlier runs of the HRRR/RAP had this low tracking north of I-94 and drawing on moisture from Lake Superior, enhancing snow rates over central Wisconsin with some amounts exceeding 6". The later runs that do have this low have taken it south of I-94 and bring the heavier snow band (2-5") closer to I-90 overnight. This is a feature we will have to watch carefully overnight and possibly issue a targeted winter weather advisory if this rouge solution pans out.

Friday-Friday Night: Windy/Snow Showers/Blowing Snow Concerns

There could be a few hour lull in the snow Friday morning behind our overnight shortwave passage, but will be rather fleeting. By late morning, a cold front will be barreling through the forecast area, with rapidly steepening boundary layer lapse rates leading to HCR-type snow showers during the midday/afternoon. Winds at the top of the boundary layer increase to 30-35kts--mainly west of the Mississippi River-- which could result in lower visibilities (1-3sm) within any of these showers.

The moisture and instability profiles along the actual cold front appear limited in nature (reflected in the explicit reflectivity progs), which would negate the snow squall risk along the frontogenesis band. The lack of forcing within the post-frontal airmass and bare ground will likewise limit the blowing snow/snow squall risk later in the day. Therefore, given these factors, have leaned against issuing a winter weather advisory for now. These showers continue into the evening but wane in intensity and coverage.

The Weekend: Periodic Light Snow

Cyclonic flow persists into Saturday morning as the stacked Great Lakes low pivots and slowly departs to the northeast. A few light snow showers may rotate around the low with any attendant weak perturbations, but amounts and impacts look to be minimal (<0.5"). Surface ridging builds for Saturday afternoon and night and keeps the risk for snow at bay. Another clipper wave cascades down the longwave ridge to the west, affecting the area Sunday into Sunday night. While the medium range solutions have come into agreement on this system occurring, exact snow amounts remain tough to nail down. Initial indications are that snow amounts should be on the lighter side (around 1 inch) and focused more over northern Wisconsin, still subject to adjustments.

Cold Weekend/Early Next Week

The aforementioned cold front heralds a stark transition back to wintertime temperatures for the weekend and start of next week. Highs on Friday will be reached during the morning with falling temperatures during the afternoon. Temperatures fall 20-25 degrees Friday by the evening and struggle to rise out of the single digits to low teens on Saturday. Exactly how low temperatures fall will be dependent on cloud cover, especially Saturday night as the surface ridge passes. Roughly 10-20 percent of the NBM ensemble members have low temperatures of -10 to -15 for Sunday morning, a plausible scenario given the fresh snowfall and potentially clearing skies.

A similar setup could play out Monday night behind the latter clipper wave discussed above with a 10-20% chance of seeing lows reach -20 north of Highway 10. Looking ahead, temperatures do moderate closer to normal by midweek, but will be a far cry from the warmth we saw over the past week. There is a signal for colder temperatures returning for the end of next week with us lingering in this broad longwave trough pattern, but model spread is large at this range.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 1119 PM CST Thu Jan 15 2026

Several shortwave troughs will move southeast through the area through Saturday. Each of these waves will produce a round of light snow which will lower ceilings and visibilities into the IFR/MVFR categories. As far as snow amounts, each wave will produce anywhere from a trace to a half inch.

ARX WATCHES/WARNINGS/ADVISORIES

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