textproduct: La Crosse

KEY MESSAGES

- A quick hitting round of snow this afternoon with snow amounts around 1-3", mainly in northeast Iowa and southwest Wisconsin. Increasing northwest winds this afternoon and evening will likely result in blizzard conditions over parts of northeast Iowa and reduced visibilities into southwest Wisconsin.

- Dangerously cold temperatures and wind chills settle across the region Thursday night and last into the weekend with morning wind chill values of -30 to -45.

UPDATE

Issued at 1040 AM CST Wed Jan 21 2026

Recent CAM and upstream radar/observation trends have resulted in several adjustments to the forecast. The lower tropospheric shortwave is showing signs of closing off as it approaches our area. This has impacts to both the wind and snowfall forecasts. First, the strongest winds look to be funneled more into north- central into eastern Iowa, with a VERY tight gradient in the winds from south to north until the wave passes through and CAA ensues. This setup will also amplify the winds within this corridor with HRRR forecast soundings showing winds of 45-50 kts at the top of the mixed layer.

This metamorphosis also will strengthen a 850-700-mb frontogenesis band right along the northern side of this wind corridor. While the duration of this frontogenesis band will be short-lived, it could still put down 2-3 inches of snow in a hurry. The big question is exactly where this gradient between blizzard and sub-headline conditions sets up. Have played a somewhat aggressive approach with the headline updates with the expectation that the worst conditions will be in the southern parts of these counties in the blizzard warning and winter weather advisory.

DISCUSSION

Issued at 418 AM CST Wed Jan 21 2026

Snow showers this afternoon, potential blowing snow.

Another shot of snow is expected this afternoon as a shortwave within the northwesterly flow aloft drops out of Alberta. Cold temperatures aloft with this wave along (highly relative) warm surface temperatures should lead to sfc-850mb lapse rates around 8-9 C/km. With a decent amount of mid-level moisture in place, as evidenced by ongoing cloudiness, should (75-100%) get some snow showers as the wave moves through. Given quick movement of the wave, this period should be short, limiting accumulation to around 1". Main concern with the snow showers is the potential for strong wind gusts and reduced visibility to occur with them as 21.00z HREF depicts 35-45 knot winds at 850mb across northeast Iowa and far southwest Wisconsin. Progged strongest 850mb winds are generally along and south of an Albert Lea MN to Platteville WI line. Given that this includes locations that received the most snow Tuesday, am concerned that strong gusts will lead to blowing snow as new snow falls, reducing visibility to as low as a 1/2 mile. Have therefore issued a Winter Weather Advisory for portions of NE IA where strongest winds and new snow are best co-located, leaving out Clayton/Grant Counties due to less favorable terrain and tree cover characteristics. This Advisory area also covers where Will need to closely monitor conditions extending northward into Dodge/Olmsted/Mower/Fillmore counties in MN as gusts to 40 mph may (50% per 21.00z HREF) occur there as well and snow cover characteristics are less certain.

Dangerous cold arriving Thursday night

Forecast remains on track for a seasonable but statistically anomalous cold outbreak starting Thursday night, when a sub 500dam 500mb upper low churns southeast over Ontario. With the surface high in the wake of this feature building over ND, surface pressure gradient on Friday morning should be enough for winds around 10-15 mph out of the northwest to persist as air temperatures plunge well below zero (60-100% chance to drop to -10 or lower). Widespread wind chills under 35 below (probability approaching 100% per 21.00z LREF) areawide appear very likely. Needless to say, the Extreme Cold Watch remains in effect and will likely move to a Warning soon given these probabilities.

Of lower certainty is how long this highly dangerous cold persists. Air temperatures bottom out Saturday morning as the aforementioned high looks to be centered in or near our CWA and clearing skies and light winds occur as a result. Given the light winds, wind chills reaching -25 are very likely (80-95%) but -35 will be tougher outside of our northern counties (15-60% south of I-94). Approach of an upper trough Saturday night may lead to a period of (relative) warm advection at 850mb and mid-level cloudiness, holding low temperatures to the single digits below zero. Given this uncertainty, have elected to not extend the Extreme Cold Watch in time beyond noon Saturday at this time.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1142 AM CST Wed Jan 21 2026

IFR to VFR conditions currently present across the region as an area of snow moves in from the west/northwest. Visibilities with this area of snow generally sit in the low end MVFR to IFR range with CIGS generally in the MVFR category. This will continue to move through the region over the coming hours. As winds pick up on the back side of this event, BLSN will be possible, especially west of the river at KRST for a couple hours. Sustained winds will veer to the northwest through the afternoon and pick up to between 10-20 kts with gusts up to 35 kts possible. Winds will then decrease later overnight to between 8-15 kts sustained. Visibilities are expected to gradually improve through the evening and overnight hours with CIGs scattering out to VFR later in the period.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Extreme Cold Watch from late Thursday night through Saturday morning for WIZ041>044-053>055-061. Extreme Cold Watch from Thursday evening through Saturday morning for WIZ017-029-032>034. Winter Weather Advisory from 5 PM this afternoon to 11 PM CST this evening for WIZ061. MN...Extreme Cold Watch from late Thursday night through Saturday morning for MNZ096. Extreme Cold Watch from Thursday evening through Saturday morning for MNZ079-086>088-094-095. Winter Weather Advisory until 11 PM CST this evening for MNZ086-094. IA...Winter Weather Advisory until 1 PM CST this afternoon for IAZ008-018-019. Blizzard Warning until 11 PM CST this evening for IAZ008-018- 019. Extreme Cold Watch from late Thursday night through Saturday morning for IAZ008>011-018-019-029-030. Winter Weather Advisory until 11 PM CST this evening for IAZ009-010. Winter Weather Advisory until 11 PM CST this evening for IAZ029-030.