textproduct: La Crosse

KEY MESSAGES

- Periods of flurries are possible this morning (10-20%) ahead of a quick hitting system that moves through the Midwest this afternoon and evening, bringing additional flurries and light snow (30-90%). Probabilities for snow are highest over far southwest Wisconsin (60-90%), where around an inch of snow is possible.

- Below normal temperatures are expected through the new week. The coldest temperatures are expected Thursday morning when subzero lows are likely (70-90%). Dangerously cold wind chills in the double digits below zero are possible, mainly west of the Mississippi River.

- Snow is possible again Wednesday (20-40%) and Saturday (10-30%).

DISCUSSION

Issued at 404 AM CST Mon Dec 1 2025

Today

A positively titled trough over the central United States this morning will quickly translate eastward throughout the day, supporting snowfall potential across the Midwest. Modest low level warm air and moisture advection this morning could support periods of flurries ahead of the wave.

Stronger forcing associated with this wave moves in this afternoon and evening as the left exit region of a 500hPa jet streak overspreads the area over top weak positive vorticity advection within the mean flow and the aforementioned low level moistening. The strongest forcing remains to the south over eastern Iowa into central Illinois, and a southward trend of the highest precipitation probabilities is noted in the 01.00z HREF in response. However, modest forcing is still expected to nudge over our far southern counties which is anticipated to coincide with the DGZ which should promote measurable snowfall. Overall, not much more than a light dusting of snow is expected for most today with areas over southwest Wisconsin receiving around 1 inch, but if the southern trend continues, amounts will likely decrease.

Outside of the snowfall, high temperatures today top out in the upper teens to low 20s with light southerly winds.

Below Normal Temperatures

Cold temperatures remain situated over the Upper Mississippi River Valley through the week under primarily northwest flow with highs generally 5-10 degrees below normal. Thursday is expected to be the coldest day this week as strong cold air advection moves in behind a cold front that traverses the region on Wednesday. Confidence is high that temperatures will be below zero areawide Thursday morning, as the 01.00z NBM continues to depict subzero temperatures with a 25th-75th spread of 5 degrees or less on average and the 90th percentile at or below zero. Along with these temperatures, dangerously cold wind chills are possible during this period with current apparent temperatures in the double digits below zero. Those west of the Mississippi River will see the coldest apparent temperatures, with a 20-40% probability of falling below advisory criteria for a time per the 01.00z LREF, primarily dependent on the strength of the low level wind field and the timing of a low level ridge axis moving into the region.

Additional Snowfall Through the Week

Active upper level flow is expected through the week with several shortwave troughs traversing the region. These shortwaves will be the catalyst of additional snowfall potential.

The first shortwave moves through on Wednesday, supporting the aforementioned cold front. Moisture increases along the front which combined with forcing from the front itself should support some developing flurries to light snow (20-40%). Steepening low level lapse rates reaching into the DGZ are possible in the afternoon under diurnal heating and low level cold air advection, which could act to support flurries through the afternoon.

More appreciable snowfall is possible Saturday night through Sunday, as another 500hPa shortwave trough sinks southward out of Canada, promoting surface cyclogenesis over the Great Plains. Confidence remains low with regard to how this period ultimately plays out as 01.00z LREF cluster analysis paints several scenarios regarding timing and location of these features. However, this system could support impactful snowfall across the area, so continues to be a period to monitor in the coming days.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 548 AM CST Mon Dec 1 2025

Widespread MVFR/IFR ceilings are observed across the region this morning with local areas of LIFR ceilings, mainly west of the Mississippi River. Not expecting much improvement through the day as low level moisture remains situated over the region, although locations with LIFR ceilings this morning are anticipated to improve to at least IFR by the afternoon. Flurries to light snow are possible by mid-morning, lingering through this evening. Localized MVFR/IFR visibilities are expected within the snowfall, most probable over northeast Iowa and southwest Wisconsin where the heaviest snowfall is anticipated. Winds will be light through the TAF period, generally 5-10kts from the south to southwest.

ARX WATCHES/WARNINGS/ADVISORIES

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