textproduct: La Crosse

KEY MESSAGES

- Light snow rest of the afternoon, exiting east by mid evening. Generally minor amounts (1/5 to 1") and mostly confined from around I-90 northward.

- Saturday winter storm trending more northward, putting more of the local area under the threat for several inches of snow. A Winter Weather Advisory is in effect for much of southeast MN, northeast IA and parts of southwest WI for 3 to 6" of snow.

- Periodic snow chances continue for next week.

- Unseasonable cold also persists, but could creep above freezing for a few hours Tue.

DISCUSSION

Issued at 244 PM CST Fri Dec 5 2025

> REST OF TODAY-THIS EVENING:

Ongoing snowfall this afternoon tied to a frontal boundary evident in significant surface wind shift along western peripheral counties in southeast Minnesota and northeast Iowa slowly sagging southeast while tightening through morning hours from an accompanying upper level trough on GOES water vapor imagery. A meager intensification in synoptic and mesoscale forcing with the tightening of the boundary increased radar reflectivity returns early this afternoon as the snow traversed the Mississippi River Valley. Resultant snowfall rates ushered in lower visibilities, closer to 1SM climatology during -SN, across most of the forecast area. Expect snowfall to continue southeast, providing up 1" in accumulation, through the evening hours. While previous concerns regarding freezing drizzle remain, off surface temperatures <-10C in the saturated airmass would suggest ice introduction and flurries instead of drizzle.

> SATURDAY: winter storm taking aim on the region with storm track trending more northward, bringing more of an impact/potential for higher snow amounts to the local area.

The northward shift of storm system for Saturday continued with some of the latest short term guidance - namely the RAP and HRRR. This resulted in approx 100 mile jump north in accumulating snows earlier this morning. NAM did a similar shift. There is still some shifting in the track as some of the later morning runs are not as aggressive with the northward push - so track is not locked in, but trends do back some of this northward shift.

Deep QG convergence, good isentropic upglide on the 280:295K surfaces, sloping Fgen, along with upper level jet support and the shortwave itself provide ample lift with plenty of moisture to produce a swath of snow. It's a fairly quick mover with CAMS pushing snow across locations west of the Mississippi river by mid/late afternoon Sat, spreading eastward through the evening and exiting east by 12z Sun.

While storm track, and thus where the greater snow amounts are realized, continues unclear, the trends for 5 to 7" in the "heart" has remained for the past few days. With some shift north looking reasonable, this brings a 3 to 6" area of snows from around I-90 in southeast MN, east to the MIssissippi River, and then south of there. Per coordination with surrounding offices, have elected to issues a Winter Weather Adv for these locations. 12z HREF isn't keen on more than 6 with near 0% shot over northeast IA - albeit with a 10:1 ratio. With expectations more in the 15:1 arena, chances from 5 to 10% are probably closer to the mark. That said, the 09z run of the REFS push 60+% threat for 6 or more inches across parts of SE MN/NE IA. Big difference. Do believe that locally higher 6"+ are possible, mostly for northeast IA. An upgrade to a winter storm warning for a portion of the local area can't be ruled out.

A shot of colder air follows in the the wake of the storm system. Highs Sunday will top out in the teens with single digits above/below zero Monday morning.

> NEXT WEEK: periodic precipitation chances with below normal temps persisting.

Progressive, northwesterly upper level flow looks to hold through next week with good agreement in all the WPC clusters. Some hints of ridge building moving into the weekend, but not much clarity that far out.

GEFS and EPS members continue to parade a myriad of shortwave troughs across the region. Decent consensus in most of the ensemble members for a couple ripples in the flow to push across the region Mon/Mon night. Relatively weak with more focus across the north. Chance for light snow with both with minimal accumulations.

Tue night looking more interesting with a stronger shortwave progged to drop out of Canada and across the upper mississippi river valley. GEFS and EPS paint an elongated swath of snow mostly across northern MN/northern WI. A few/several inches of accumulation could result.

The busy pattern continues after that, but with more discrepancies between the ensemble suites, thus less predictability.

Temperatures look to hold below the early December normals although Tuesday shows some promise to reach/exceed freezing for a few locations. The last above freezing day for the area was just before Thanksgiving. Its been awhile.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 533 PM CST Fri Dec 5 2025

Light snow continues through the evening for southern and central Wisconsin. Expect the snow to leave prior to midnight. Light south winds gradually shift to northwest winds this evening as a weak cold front moves through the area. Visibility reductions while it is snowing will continue. MVFR to IFR CIGS continue through much of the TAF period. There are some instances where the cloud deck may not be BKN or OVC during the early morning hours, particularly along and east of the Mississippi River, but is then expected to go back down to at least MVFR ahead of the next weather system that arrives late afternoon/evening Saturday.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Winter Weather Advisory from 6 PM Saturday to 6 AM CST Sunday for WIZ061. MN...Winter Weather Advisory from 3 PM Saturday to 6 AM CST Sunday for MNZ086-087-094-095. Winter Weather Advisory from 6 PM Saturday to 6 AM CST Sunday for MNZ096. IA...Winter Weather Advisory from 3 PM Saturday to 6 AM CST Sunday for IAZ008>010-018-019-029. Winter Weather Advisory from 6 PM Saturday to 6 AM CST Sunday for IAZ011-030.