textproduct: La Crosse

KEY MESSAGES

- A fast-hitting snow system moves through this afternoon and clears out this evening. The combination of 1-3 inches of snow and strong winds over parts of northeast Iowa will likely lead to a short period of blizzard conditions later this afternoon.

- Elsewhere across the region, snow amounts by this evening will be around 1-2 inches with patchy blowing snow at times.

- Dangerously cold temperatures and wind chills settle across the region Thursday night with the coldest readings Friday morning of - 40 to -45. These wind chills improve over the weekend, but to what degree is more uncertain.

DISCUSSION

Issued at 155 PM CST Wed Jan 21 2026

This Afternoon/Evening: Snow, Blizzard Conditions for NE Iowa

A compact but potent mesolow is developing over northwest Iowa along the leading edge of a cold front dropping across central MN into the Siouxland early this afternoon. This low is acting to both enhance winds along its southern flank and snow along its northern periphery. Wind gusts upstream in southeastern South Dakota have been gusting to 45 to 65 mph, and while the corridor of these stronger winds will be lessening and mainly passing to the south of the forecast area, there is a window of opportunity for these winds to sneak into parts of northeast Iowa. The center of the low looks to track near Highway 18 later today with the northern periphery of the strong winds slicing through Mitchell County ESE to Clayton County, IA and Grant County, WI.

The open areas of Iowa have the best potential to see wind gusts in excess of 45 kts and blizzard conditions through this evening. There will be a very tight south to north gradient in the winds as the low passes through with winds of only 10-20 kts a few miles off of this strong wind axis. Further north, the stronger winds do not arrive until the cold front passes in the evening. These winds will not be as strong, but HRRR soundings show gusts topping out at 30-35 kts for a few hours in the evening before relaxing.

Moving onto the snow, with a stronger 850-700-mb frontogenesis band taking shape right along the northern periphery of the low, radar trends from Sioux Falls show an intense band of 30-40 dBZ echoes associated with this fgen band and even a few lightning strikes. This band translates ESE over the course of the afternoon and evening and will be responsible for a 1-3 inch stripe of snow, though measuring this snow will be difficult given the juxtaposition of the strong winds. Further north and ahead of the low, broad isentropic ascent snow is ongoing over much of the area and tapers off this evening as the low moves east. All in all, the snow wraps up areawide before midnight with winds also decreasing quickly in its wake.

Thursday Evening - Weekend: Dangerous Cold

Steady cold air advection ensues tonight in the wake of our current snow system. After reaching the mid-20s today, highs struggle to reach the lower to mid teens for Thursday. A highly amplified mid to upper tropospheric West Coast ridge funnels Arctic air southward midweek, with this anomalously cold airmass arriving Thursday night ahead of a well-resolved 1050-mb high pressure cell sliding down the Canadian Rockies. With the center of the high displaced well to the northwest Thursday night/Friday morning, the increasing pressure gradient coupled with plummeting temperatures will send wind chills tumbling overnight to between -35 and -45 by sunrise Friday. With a 6-mb spread in the pressure gradient across the forecast area by sunrise Friday, temperatures should not crater too far. If the boundary layer were to decouple (say at lower elevations/ sheltered areas), some of the 10th percentile solutions of the NBM distribution has lows falling to -20 to -30. However, such a scenario would not affect the forecast wind chills much given the needed reduction in wind speeds to achieve these lower temperatures.

Friday during the day remains cold as the 1048-mb high pressure cell approaches from the west with little opportunity for wind chills to improve above -25 to -30. With the high centered over the region Friday night, lows have the potential to crater to between -20 and -30, with a few outliers (5-10% probability) pushing -35 in favored locales in the Wisconsin sand bogs and central Wisconsin. Winds will be nearly calm during this time, so wind chills may actually be slightly higher than the previous night. However, even a slight wind could send wind chills back below -30 to -40. Have upgraded the Extreme Cold Watch to a Warning for Thursday night into midday Friday where confidence in warning level impacts is the highest, but left the watch as is for Friday afternoon through Saturday morning to allow us to fine tune any transition to an advisory or continuation of the warning.

The pattern begins to moderate by the end of the weekend into early next week as a Pacific airmass works eastward with highs back to near normal by Tuesday. Exactly how fast it moderates remains a point of uncertainty in the forecast with the Arctic air lurking not far to the north.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 554 PM CST Wed Jan 21 2026

As widespread snowfall shifts southeast of the forecast area this evening, a narrow band of heavier snowfall moving into southeast Minnesota will provide another quick bout of visibility reductions across the forecast area. Therefore, have included TEMPO 1/4SM at more prone KRST TAF site. Otherwise, ongoing impacts primarily west of the Mississippi River at smaller airports in northeast Iowa from BLSN through Thursday. Wind speeds may remain increased though Thursday as well and therefore have increased from previous forecasts.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Extreme Cold Warning from midnight Thursday night to 11 AM CST Friday for WIZ041>044-053>055-061. Extreme Cold Watch from Friday morning through Saturday morning for WIZ017-029-032>034-041>044-053>055-061. Winter Weather Advisory until 11 PM CST this evening for WIZ061. Extreme Cold Warning from 9 PM Thursday to 11 AM CST Friday for WIZ017-029-032>034. MN...Extreme Cold Warning from midnight Thursday night to 11 AM CST Friday for MNZ096. Extreme Cold Watch from Friday morning through Saturday morning for MNZ079-086>088-094>096. Winter Weather Advisory until 11 PM CST this evening for MNZ086-094. Extreme Cold Warning from 9 PM Thursday to 11 AM CST Friday for MNZ079-086>088-094-095. IA...Blizzard Warning until 11 PM CST this evening for IAZ008-018- 019. Extreme Cold Warning from midnight Thursday night to 11 AM CST Friday for IAZ008>011-018-019-029-030. Extreme Cold Watch from Friday morning through Saturday morning for IAZ008>011-018-019-029-030. Winter Weather Advisory until 11 PM CST this evening for IAZ009-010-029-030.