textproduct: La Crosse

KEY MESSAGES

- As promised in yesterday's discussion, the weekend storm track wobbled. There is an increasing signal that warmer air will work up to between the I-90 and I-94 corridor, heavily impacting snow amounts for any areas that see this wintry mix.

- Confidence in the band of 12-18+ inches of snow has shifted to north of Highway 10 with there still a signal that highest amounts in this band could approach 24".

- Strong winds midday Sunday into Monday morning, coupled with the falling and blowing snow, could result in blizzard conditions. The main uncertainty is exactly where and when these conditions develop.

- Colder weather settles in for Sunday into Tuesday morning before temperatures rebound for the end of the week.

DISCUSSION

Issued at 155 PM CDT Fri Mar 13 2026

This Afternoon - Saturday Midday: The Calm Before the Storm

This morning's strong winds continue to decrease in the wake of the strong cold front that passed through last night. Winds gusted up to 60-70 mph for a few hours before sunrise, but taper off to 5-10 mph this evening. An initial round of light snow attendant with an elevated 800-600-mb frontogenesis band could bring a light dusting of snow Saturday during the day, but impacts should be minimal and the main winter storm arrives Saturday night as moisture transport increases over this fgen surface.

Saturday Night - Monday Morning: Winter Storm Details

Well, the forecast got more complicated. With a more amplified wave depicted by an increasing number of ensemble members, warm air advection within the warm sector ahead of the attendant lower tropospheric low pressure cell is stronger and pushing the wintry mix zone further north towards or even north of the I-90 corridor. The majority of the global guidance are focusing on this wintry mix along I-90, but early runs of the convective models (which have been far from stellar this winter) have pushed the warm sector north of I-94!

Needless to say, confidence has decreased in the potential snow totals within and south of this wintry mix band. Forecast snow amounts within this wintry mix zone have fallen to only a few inches before midday Sunday; however, the combination of sleet and freezing rain, coupled with the deformation zone band/wind that wraps around in the afternoon and overnight Sunday, should still result in impacts warranting of a winter storm warning along I-90. Icing amounts are also highly dependent on surface temperatures, but a localized band of ice amounts over 1/4" is possible. If temperatures fail to warm and icing remains on trees and power lines as colder air and stronger winds arrive, the risk for damage to trees and power lines increases.

This shift in the forecast highlights concerns with the under- dispersiveness of the available ensemble guidance and the risk that this band could still shift back southward over the next 24-36 hours. The culprit wave is still outside of the radiosonde network and a several county north-to-south shift in the snow band is quite plausible as the wave becomes better sampled later today and tonight. We've seen this occur with multiple events in the past few winters where the snow band made a sudden shift at the 11th hour and necessitated a quick adjustment in headlines.

Once we get past the wintry mix midday Sunday and cold air advection ensues on the backside of the low, confidence increases for how the storm and its associated impacts will evolve. Snow overspreads the entire area by mid-afternoon Sunday and continues into Sunday night with snow winding down Monday morning. Winds increase steadily during the day on Sunday as they turn to the north, with gusts of 35 to 50 mph in the afternoon into the overnight. As the snow ratios increase and the snow becomes more blowable, the risk for blizzard conditions rapidly increases for higher elevations and exposed locales. The big question revolves around the strength of the lift within this band with the GEFS members quite rambunctious with some of their totals. Have lowered snow totals over the NBM for Sunday night given the risk that winds could fragment the dendrites within the deformation zone and lower the snow ratios at the surface. A blizzard warning will in all likelihood be needed for the Sunday afternoon-Monday morning timeframe, it is just a matter where.

It goes without saying that travel may be impossible at times during this winter storm. The combination of high snow amounts and strong winds could make roads impassable, especially in open areas west of the Mississippi River and last well into Monday.

Cooling Temperatures to Start the New Week, More Snow Tuesday

Stronger CAA trailing our weekend system sends temperatures plummeting back to values more typical of early February. Highs on Monday only reach into the teens with wind chills Sunday and Monday nights in the teens below zero. This cold snap looks to only last a few days with highs rebounding back to near average through the rest of the week.

A quick hitting snow system moves through the region late Tuesday into Tuesday night, but amounts at this time only look to be a few inches at most. The details from, this storm will be refined in the coming days.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1247 PM CDT Fri Mar 13 2026

An area of low pressure will continue to shift east over the Upper Great Lakes this afternoon as northwest winds diminish through the day. This low pressure will be replaced by a ridge of high pressure tonight as winds become calm after 04-06Z. Outside of brief MVFR ceilings this afternoon, VFR conditions are expected to return over the next hour or two and remain VFR through the rest of the TAF period.

A warm front and associated trough approach from the south Saturday afternoon into the evening hours, which may bring a quick snow shower or two but chances (10-20%) are too low to mention in the TAF at this time. By Sunday morning, a strong low pressure system translates across the area, bringing strong winds, heavy snow, and freezing rain potential through Sunday and Sunday night.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Winter Storm Watch from late Saturday night through Monday afternoon for WIZ054-055. Winter Storm Watch from Sunday afternoon through Monday afternoon for WIZ061. Winter Storm Warning from 7 PM Saturday to 1 PM CDT Monday for WIZ017-029-032>034-041>044-053. MN...Winter Storm Warning from 7 PM Saturday to 1 PM CDT Monday for MNZ079-086>088-094>096. IA...Winter Storm Watch from late Saturday night through Monday afternoon for IAZ008>011. Winter Storm Watch from Sunday afternoon through Monday afternoon for IAZ018-019-029-030.