textproduct: La Crosse

KEY MESSAGES

- Low potential (10-30%) for light snow north of I-90 Thursday morning, with a few tenths of an inch possible.

- A band of snow is possible (40-60%) somewhere over the Upper Mississippi River Valley on Saturday.

- Temperatures waver late this week through the weekend. Above normal temperatures Friday quickly fall to below normal this weekend.

DISCUSSION

Issued at 1248 PM CST Wed Feb 25 2026

Today - Thursday: Low Snow Potential

Weak low level ridging and surface high pressure continue shifting eastward across the region today, resulting in predominantly benign conditions as we head into tonight.

A subtle 700-500hPa shortwave trough currently across the Northern Rockies is expected to traverse the backside of the ridge this afternoon into this evening, supporting a band of 850-600hPa frontogenesis over Iowa. With the surface high and low level ridge in place, the 25.15z RAP depicts this band staying to our southwest, keeping the vast majority of any snowfall out of our area. However, there is a signal that a few flakes could (5-10%) develop for a small portion of northeast Iowa in a few of the high resolution models.

Higher confidence in light snow occurs late tonight into Thursday morning as another shortwave shifts across northern Minnesota into northern Wisconsin. Model soundings depict a saturating column towards and after sunrise Thursday which combined with upward motion associated with the wave itself as well as divergence in the left exit region of a 300-250hPa jet core, could support light snow development through the morning commute, primarily north of I-94 (10-30%). Amounts would be light, generally only a few tenths of an inch. There is some low potential for a brief period of freezing drizzle after the initial snow north of I-94 and as far south as I-90 as some dry air works its way in aloft, leading to a loss of cloud ice, but confidence is not high in this scenario (< 10%) given a very shallow low level moist layer.

Saturday: Snow Band Potential

Looking ahead to Saturday, ensemble and deterministic guidance depict a narrow swath of snow developing somewhere over the Upper Mississippi River Valley associated with a fairly impressive 700hPa frontogenesis band. Model soundings suggest this strong forcing will coincide with a saturated DGZ, but overall moisture appears to be a limiting factor for amounts. Dry air below 850hPa shown in the soundings may result in the sublimation of dendrites falling into the layer. The biggest questions are if the frontogenesis band is able to overperform in this scenario, allowing for efficient dendrite creation to overcome this dry layer, or if low level moisture increases. If either of these scenarios come to fruition, a solution with higher amounts would become favored. Much of the ensemble suite suggests 30-50% probabilities for 1 inch or greater, but fall off to near 0% above 3 inches. The 25.13z NBM has some higher probabilities for higher amounts owing to some outlier solutions in the event of overperformance, so will be something to monitor over the coming days.

There's also still some uncertainty regarding where this stripe of snow occurs due to questions about where the frontogenesis band ultimately sets-up. The 25.13z NBM suggests an area from southern Minnesota into southern Minnesota is favored, painting 40-60% probabilities for measurable precipitation. The 25.06z EPS and 25.12z GEFS/AIGEFS support this solution, painting a very similar spatial extent, with the GEFS trending northward towards the NBM solution in the last 12 hours. So, as of right now, this appears to be the most favorable corridor for measurable snow on Saturday, but there is still time for this to shift northward or southward.

Late This Week - Weekend: Wavering Temperatures

Low level warm air advection associated with a warm front expected to lift into the Upper Midwest occurs Thursday into Friday, resulting in warming temperatures through the end of the week. Highs climb into the 50s Friday afternoon for portions of the region with little variation in the 25th-75th percentiles. The exception is for those with a snowpack, specifically northeast Iowa into north-central Wisconsin, where temperatures will be moderated to the mid 40s owing to the snow's higher albedo and the evaporative cooling effects on the surrounding airmass.

However, the spring-like temperatures don't last long. As we head into Friday evening, the 25.00z LREF depicts a dry cold front shifting through the region, supporting strong cold air advection in its wake. This will bring about rapidly cooling temperatures through the low levels, plunging 925hPa temperatures to -10C to -15C. As such, highs are expected to peak in the 20s and apparent temperatures in the teens through the weekend.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 553 PM CST Wed Feb 25 2026

Increasing low level moisture threatens widespread MVFR/IFR and areas of LIFR ceilings through early Thursday morning. Highest probabilities lie west of the Mississippi River Valley in southeast Minnesota and northeast Iowa affecting smaller airports as well as KRST TAF site. Smaller airports and KLSE that lie in river valleys may be less affected by lowest ceilings given the lower elevations. Further impacts from below freezing surface temperatures initially with FZDZ possible albeit lower (30%) likelihood given thickness of low level saturation. Light snow causing IFR visibilities at smaller airports in central Wisconsin north of Interstate 90 through Thursday morning as well.

Eradication of low level saturation expected through the afternoon.

ARX WATCHES/WARNINGS/ADVISORIES

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