textproduct: La Crosse

KEY MESSAGES

- Our long awaited winter storm has arrived, with light to moderate snow ongoing across the area through this evening. Winds will ramp up this evening as snowfall tapers off, leading to reduced visibility as blowing snow occurs. Near- blizzard conditions are likely (70% chance to drop below 1/2 mile visibility) west of the Mississippi River valley.

- 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 Monday morning and Thursday morning.

- Additional snow may (10-30%) occur Monday into Monday night, Wednesday, and Thursday night into Friday. Thursday night into Friday could presumably lead to impacts but details are far too murky to make any conclusions at this time.

DISCUSSION

Issued at 209 PM CST Sat Nov 29 2025

Snow continues, looking ahead to blowing snow potential tonight

Light to moderate snow is ongoing across the CWA and a large swath of the Midwest early this afternoon. Highest reports have occurred to our south along Highway 20 roughly between Fort Dodge and Hazelton where 8 to 12 inches of snow has fallen and continues. In our neck of the woods, totals have generally been coming in on the lower side of expected ranges with highest amounts in the south - Oelwein had an estimated 8 inches as of noon - and lower amounts in our north.

While totals have been a bit underwhelming thus far, given that we expect the surface low to shift closer to our CWA and that lift will be on the increase on the large scale as the main upper trough approaches from the west and a zonal upper jet advances over IA, have only adjusted event totals lower by 1-2 inches. Additionally, forcing for ascent should be enhanced in our west by a 700/850mb frontogenetic zone that is currently located over southern MN and is leading to enhanced snowfall per latest surface obs, radar returns, and webcam images.

Remaining questions surround potential for near-blizzard to blizzard conditions this evening into tonight. As the surface low approaches and deepens, northwesterly 40 knot 850mb jet sets up along and west of a Rochester to Oelwein line while surface pressure rises approach 1 mb/hr. Am highly confident (90%) gusts will reach the 35-40mph range during the late evening into the nighttime hours. Uncertainty surrounds how low visibility will drop. Per 29.12z HREF probs, wind gusts will begin to reach 35 mph closer to 10pm while the 700/850mb frontogenetic zone discussed above will begin to dissipate a few hours before that. Thus, visibility reductions should focus on the ability for the winds to loft fresh snowpack into the air. Consequently, thinking the chance to reach a quarter mile or less is low (20%) with a very small (10%) chance for visibility to remain around 1 mile or greater during the overnight hours. Most probable outcome (70%) is for visibility to hold around a half mile, enough for impacts to continue overnight. Have therefore kept the Winter Storm Warning going through the overnight hours even though new snowfall should largely end after midnight. If the 700/850mb band lingers longer than expected or these gusts generate lower visibility by lofting snowpack than expected, would need to explore a short fuse upgrade to a Blizzard Warning. Will thus closely monitor obs, radar, and webcams in southern Minnesota (status of the snow band) and the central third of Iowa (ability for winds to loft snow as winds will increase in this region first).

Cold week ahead

Persistent cyclonic flow centered over the eastern third of Canada and the CONUS will lead to cold conditions for the next week. Coldest mornings will occur after upper waves depart to the east when surface ridging is maximized. Monday morning and Thursday morning continue to appear to be the coldest in the 29.12z guidance suite, when wind chills are favored to below zero across the area and in the double digits below zero in parts of SW MN. Thursday morning may see some values near -25, so will need to continue to monitor this period over the coming days.

Additional shots at snow

Upper waves mentioned above will quickly translate over the central CONUS Monday into Monday night, Wednesday, and again Thursday night into Friday. At this time, pattern suggests some chance at impacts with the Monday/Monday night wave and the Thursday night/Friday wave. For Monday/Monday night, guidance has been fairly insistent over several cycles that impactful snow will remain to our south. For Thursday night into Friday, guidance has large spread with regards to both timing and trajectory with an upper wave ejecting northeastward from the Four Corners. At this time, NBM guidance seems prudent across these time periods, but will need to watch Thursday night into Friday closely over the coming days.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 501 PM CST Sat Nov 29 2025

Widespread IFR/LIFR conditions currently present across the region with ongoing light to moderate snow. Snow will continue through this evening before coming to an end from west to east overnight tonight. North/northwesterly winds are expected to pick up as this system moves out of the area after 06Z which could create some BLSN at RST for some time overnight. Gusts during this timeframe are expected to be in the 20-30 kt range at the terminals. Visibilities will likely remain in the IFR category into early tomorrow morning before improving as gusts also start to decrease. CIGs will remain MVFR for much of tomorrow before scattering out to VFR tomorrow afternoon.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Winter Storm Warning until 6 AM CST Sunday for WIZ029-032>034- 041>044-053>055-061. Winter Weather Advisory until 6 AM CST Sunday for WIZ017. 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.