textproduct: La Crosse

KEY MESSAGES

- Breezy today with wind gusts mostly between 25 and 35 mph into the evening.

- Precipitation chances increase Sunday night into Monday morning with potential for mixed precipitation, mainly along and north of I- 90.

- Above normal temperatures for much of next week with highs generally in the 30s and 40s through midweek and potentially some 50s on Christmas Day for portions of northeast Iowa and southwest Wisconsin.

DISCUSSION

Issued at 119 PM CST Sat Dec 20 2025

Today-Monday: Dry Weekend, Mixed Precipitation for Monday?

As a cold front continues to move southeast across the region today, a surface high sits over the Upper Midwest through the weekend. There is a little lag in the colder air arriving, as it moves into the forecast area this evening and linger through the overnight. High temperatures for today remain in the upper 20s to low 30s, however that high will likely by the early afternoon as the rest of the afternoon, temperatures gradually decrease. For the remainder of the day, better mixing is expected as sustained winds of 15 to 25 mph with gusts of 25 to 35 mph will be possible into the evening. Looking at RAP and HRRR soundings for potential high end wind gusts, areas to the north of I-94 have the best chance at seeing wind gusts approaching 40 mph. The stronger winds gradually shift east as the day progresses so areas to the west will see their winds diminish before areas north of I-94 and east of the Mississippi River. By this evening, the aforementioned colder air arrives, lowering our overnight temperatures into the single digits above and below zero. The below zero temperatures likely will stay along and north of I-94. Heading into Sunday, we get a little warm air advection with a southwest wind that increases our temperatures back into the mid to upper 20s for most.

By Monday, the surface high is into the Ohio River Valley and the area gets into zonal flow. The warm air advection continues Sunday night into Monday as the southwest winds remain. Moisture transport begins to increase late Sunday evening as a weak warm front shifts northward into our area. This will be the kick starter for precipitation in eastern Minnesota and Wisconsin. As precipitation begins, the further north you are the more likely the precipitation type will be snow and gradually warm up to rain. The further south you are, precipitation should begin as snow, however based on forecasted soundings between I-90 and I-94, a well-defined warm nose is present between 1000 and 3000ft. The best lift is also within the cloud layer. The RAP does a good job showing this lift using the 700mb vorticity. At the same time, dewpoints remain quite dry in the lowest 1500ft or so. Dewpoints will gradually increase as the warm front approaches. The potential concern here is that the precipitation type, based on these parameters could be freezing rain for the locations between I-90 and I-94, and could finish off as freezing rain for northern locations. There is still a bit of uncertainty with a few things regarding the precipitation for Monday. The first is how far north the warm front gets and the associated moisture transport. Each model is showing the precipitation initiating somewhere in our forecast, but some have it closer to the Twin Cities and others north of I-94. Another uncertainty is while temperatures gradually warm during this precipitation event, if the atmosphere cools down to the wet bulb, this would be mostly be all snow everywhere, lowering the chance for freezing rain. Lastly, do we get precipitation to reach the surface based on how dry the near surface atmosphere is? Overall, precipitation chances increase Sunday night into Monday morning but as far as precipitation type and if it does precipitate, those variables are uncertain at this time, especially the further south you go. Areas north of I-94 should see precipitation and likely snow for a few hours before a potential transition.

Tuesday-Friday: Mostly Dry and Warmer Temperatures

The zonal flow becomes more southwesterly as a ridge builds in and lingers through much of week. Good warm air advection helps to increase temperatures into the mid to upper 30s for Tuesday and the upper 30s to low 40s for Christmas Eve. Some ensemble members, about 30 to 50%, show light measurable precipitation on Wednesday into Thursday as a wave sneaks under the ridge. The better precipitation chances are south and east of our forecast area. Ensemble guidance also favors the ridge amplifying Wednesday and Thursday, however there is uncertainty on how amplified the ridge gets. The deterministic GFS and about 30% of GEFS members have a cooler solution keeping temperatures cooler than forecasted. There is also about 70% of EPS members supporting this solution as well, however based on 06Z EPS members, they have warmed up a little bit compared to the 00Z run. Based on 00Z LREF, there is a 40% chance that the ridge is more amplified, leading to warmer temperatures across the forecast area, especially for Christmas Day. The probability for seeing 50 degrees in these two clusters for Christmas is between 20 and 50% for areas south of I-90 in one cluster which represents 21% of all ensemble members. The other cluster represents 19% of all ensemble members and is the warmest solution of all of them, suggesting a 40 to 80% chance of at least 50 degrees, with the highest chance in northeast Iowa and far southwest Wisconsin. Overall, above normal temperatures are likely for this week, how warm we get is the main question and another thing to note is that, depending on how much snow cover remains on Wednesday and Thursday will also impact temperatures.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1121 AM CST Sat Dec 20 2025

VFR conditions expected through the period. Winds have been increased across the area today with gusts of 25-35kts expected through later afternoon. A slow decrease is expected through the evening.

Outlook: We are watching for some possible wintry weather Monday morning. The low-levels appear to be drier and precipitation will struggle to reach the surface. If it can, a very light wintry mix may be the result...chances increase to the north (40-50% northcentral WI, 10-20% northeast IA).

ARX WATCHES/WARNINGS/ADVISORIES

WI...None. MN...None. IA...None.