textproduct: La Crosse

KEY MESSAGES

- Some patchy freezing drizzle or flurries could be around overnight but impacts should be minimal with some light snowfall today and some treatment on the roads. Will need to monitor for additional impacts or possibly a Winter Weather Advisory late this afternoon and evening before strongest forcing exits.

- Some additional light snow is still expected Wednesday as the arctic front moves through from north to south early. Amounts should be less than 1/2 inch and roughly I-94 and south. Temperatures will be falling in the afternoon.

- New Years Eve/Day onward: Cold with single digit below zero wind chills NY eve, highs only in the teens NY day. Otherwise, seasonable temperatures with little/no precipitation expected through Wednesday.

DISCUSSION

Issued at 125 PM CST Tue Dec 30 2025

Patchy Drizzle or Flurries Tonight

Challenging forecast for today bleeds into tonight with strong warm advection in the 850-925mb layer shifting east of the area and lift waning per short term model consensus. For the later afternoon, areas west of the Miss river have some chances (50%) for freezing drizzle as the cloud depths are favoring loss of ice. This evening, lingering boundary layer moisture appears to remain per model forecast soundings with around 1.5km of depth and a somewhat mixed shallow boundary layer with weak cold advection overnight. This 1.5km saturated layer in the soundings is probably (75% chance) supercooled liquid with mainly subsidence indicated. However, west of the Miss river, steeper low-level lapse rates are found overnight again per consensus model output with some weak cold air advection, which could cause some lift in that layer...which may also just reach ice nucleation temperatures of minus 10 to 12C. So, kind of messy to call deterministically, but some very light precipitation could fall. Impacts would be limited it seems with very low precipitation amounts if they occur at all. For now, have carried some freezing drizzle and snow chances (15-20%) along I90 and south basically. Confidence is low on the overnight period.

New Years Eve and Day - Additional Light Snow

Northwest flow continues with strong shortwave trough energy moving through the Great Lakes off to the northeast Wednesday. Per multi-model analysis, the upper tropospheric QG convergence and lift just brushes central WI. Surface observations show the Arctic front currently positioned along the U.S.-Canadian border with single digit temperatures along it from MN east. As the trough swings through the flow, the arctic front in lower levels drives through the area early Wednesday, bringing boundary layer instability and strong cold air advection / cooling temperatures. 700-800mb frontogenesis also intensifies across the area which all should allow for deeper column saturation and a period of light snow moving in from the northwest in the morning, snowing in the 9am to 3pm window. It would seem that I-94 and south would be most favored and have kept the 60-70% snow chances. This matches the 30.12Z HREF 6-hour probabilities for 0.01" (axis from MSP->MSN). Amounts should generally be less than 1/2" as the forcing is transient and lift weak overall (model consensus in the -3 to -5ub/s range).

Friday through Wednesday

While there are some weather systems that could affect the area, predictability is pretty low on these "lighter" weather makers. Overall, the forecast is nearly dry through this period with seasonal temperatures.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 528 PM CST Tue Dec 30 2025

Wide range of conditions across the area ranging from IFR across West Central Wisconsin to VFR across portions of NE Iowa. An area of freezing drizzle has overspread much of the area leading to icy conditions, especially across West Central and Southwest Wisconsin. While some pockets of IFR CIGs remain with this activity, CIGs will predominantly reside in the MVFR range through the rest of the night and through the day tomorrow. Chances for freezing precip decrease later into the evening with low chances (less than 20%) of freezing drizzle lingering overnight along and south of the I-90 corridor across SE Minnesota and NE Iowa. Will continue to monitor trends to see if observations support adding in a prevailing group at the terminals for freezing precip but have left mentions of it out for now with low confidence in this scenario panning out.

Another round of snow looks to move in from the northwest tomorrow morning and continue through the region into the afternoon. Snowfall is expected to be light but will likely bring MVFR visibilities to the terminals for a period of time. Snow chances will decrease through the afternoon with dry conditions expected towards the tail end of the period. Winds will remain out of the northeast through the period with sustained wind speeds generally holding in the 8-15 kt range.

ARX WATCHES/WARNINGS/ADVISORIES

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