textproduct: La Crosse

KEY MESSAGES

- A winter storm moves through the region tonight through Saturday night providing a prolonged period of accumulating snow. Probabilities for 6+" of snow are 70-95%, highest along and south of I-90 with areas in northeast Iowa and far southwest Wisconsin potentially (20-80%, increasing north to south) reaching a foot. Blowing snow may occur west of the Mississippi Saturday evening.

- Cold temperatures remain through next week with highs in the upper teens to mid 20s. Overnight lows fall into the single digits above and below zero Sunday night into Monday morning and potentially again Wednesday night into Thursday morning. - Additional snow may (20-35%) occur Monday into Monday night, Tuesday night into Wednesday, and Thursday night.

DISCUSSION

Issued at 150 PM CST Fri Nov 28 2025

Winter storm on tap

18z WV satellite shows a broad upper trough over ID and an upper low over Quebec. Westerly upper jet over UT/CO is being sampled by GOES with 50-60 knot winds over the Rocky Mountain Front Range from NE NM northward to WY. At the surface, lee troughing is ongoing in the western High Plains. Farther east, broad surface high is present in the wake of the eastern upper low. Temperatures in the forecast area are in the mid 20s with surface dewpoint depressions around 10-15 degrees F.

Today into tonight, as the western upper trough advances southeastward, lee surface low will develop in SE CO and hook toward NE MO. With the surface high shifting to the eastern CONUS, southerly low level moist advection will occur across the central CONUS, leading to widespread precipitation. In our neck of the woods, despite the southerly fetch in the low levels, temperatures will remain below 0C through the column with saturation extending through the DGZ. Therefore, snow remains the only expected precip type in our CWA. Precip generation will focus on two regimes - the initial warm advection tonight into Saturday morning and then as lift occurs ahead of the main body of the upper wave while moisture continues to wrap around the north side of the surface low. This should result in a prolonged period with moderate snow with highest amounts in northeast Iowa and far southwest Wisconsin where lift and snow residence time will likely be maximized. Of particular interest is the presence and location of any enhancement due to frontogenesis. Trend noted in previous update toward the presence of an axis of modest 900-700mb frontogenesis continues in short term guidance this morning and in the 28.12z global suite. 28.15z RAP suggests this will be located from roughly Charles City IA to Menominee WI Saturday evening, potentially enhancing snow totals in this area. Thus, while totals will tend to follow a consistent north to south gradient, could see some enhancement west of the Mississippi Valley and the highest totals within our CWA in Floyd/Chickasaw Counties.

As for what those amounts are, with around 18-24 hours of snow rates of between 0.5-1" per hour and surface compaction ongoing through the event, am very confident (75-95%) areas along and south of Interstate 90 will receive at least 6". Slight northern jog in track of the low has continued with latest guidance, so have increased amounts around 1" across the board and added Clark County to the Winter Storm Warning. As for who gets closer to the 12" mark, our southern counties (Floyd-Chickasaw-Fayette-Clayton IA and Grant WI) have the best shot, 50-80% per 28.12z SPC HREF output.

Finally, with the closer track of the surface low, 35 mph wind gusts appear very likely (80-100%) Saturday evening, particularly west of the Mississippi. Should any location experience moderate snow as these gusts occur, very low visibility (1/2 mile or less) would result. Will need to closely monitor end timing of moderate snow rates as this combination would lead to a corridor of highly dangerous driving conditions within the broader issues across the region.

Cold next week

Extended period of mainly northwesterly flow aloft is expected in the wake of Saturday's upper wave. This should lead to an extended period with below normal temperatures. Coldest mornings should be Monday and Thursday mornings (28.12z NBM 40-90% and 30-80% chance for subzero lows, respectively). Breezy conditions appear unlikely, so wind chills should remain above advisory level (-25).

Additional shots at snow

Passing upper troughs within the northwesterly flow aloft may lead to additional light snow showers or flurries Monday, Wednesday, and Thursday night. Monday and Thursday night appear to have the potential to generate additional hazardous travel conditions should everything come together, however Monday's snow looks likely (80%) to remain to our south and guidance spread in key timing and location details is large for Thursday night. Too early to make pronouncements but something to keep an eye on once Saturday's snow departs.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 1135 PM CST Fri Nov 28 2025

MVFR to IFR conditions associated with light to moderate snow SW of a SYN-to-PVB line as of 06Z lift northeastward overnight and will be established for the day on Saturday areawide. LIFR visibilities in the heaviest snow are expected from mid-morning through the evening today. Confidence in how quickly conditions improve overnight is low as easterly winds today switch to the northwest tonight and increase to 10-20G25-35kts, which could result in blowing snow well into the morning on Sunday. The greatest risk for near blizzard conditions during this period will be west of the Mississippi River. Overall conditions should improve through the day on Sunday as winds subside and the snow departs.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Winter Storm Warning until 6 AM CST Sunday for WIZ053>055-061. Winter Weather Advisory from 6 AM Saturday to 6 AM CST Sunday for WIZ017. Winter Storm Warning from 3 AM Saturday to 6 AM CST Sunday for WIZ029-032>034-041>044. MN...Winter Storm Warning until 6 AM CST Sunday for MNZ079-086>088- 094>096. IA...Winter Storm Warning until 6 AM CST Sunday for IAZ008>011-018- 019-029-030.