textproduct: La Crosse

KEY MESSAGES

- Near-record warmth today with highs in the 70s to near 80 gives way to colder than normal temperatures by mid-week.

- Isolated strong to severe storms possible overnight and into Tuesday morning. The primary threat with any strong to severe storms will be large hail.

- Potential for wintry mix (40-70% chance) Wednesday night and into Thursday. Snow and ice accumulations will be possible during this period, however confidence in exact amounts is very low at this time.

DISCUSSION

Issued at 1157 PM CDT Sun Mar 29 2026

Today - Tuesday: Near-Record Warmth Today, Storms Monday Evening into Tuesday Morning

Upper-level zonal flow and weak ridging combined with southerly surface flow will be the drivers for our very warm temperatures today with the NBM inter-quartile range for highs ranging from the lower 70s to lower 80s across much of the area. Fairly decent mixing to around 850mb in the recent RAP/HRRR coupled with a dry layer above this will allow for minimal cloud cover and larger dewpoint depressions near the surface. As a result, would not be surprised if we trend towards the higher percentiles of NBM and knock on the door of some daily records in spots.

As we head into the late evening and overnight hours, the combination of an EML at 700mb and an increasing axis of 850mb moisture transport has much of the CAMs instigating a region of convection near the triple point of IA/IL/WI as these ingredients interact with a quasi-stationary boundary. Overall, RAP/HRRR soundings depict a fairly pronounced capping inversion in this region with MUCAPE values of 1500-2500 J/kg and fairly decent mid- level lapse rates of around 8 C/km. While shear profiles are not overly impressive in the unstable layer with only slight hodograph elongation, the more robust thermodynamics would certainly suggest a hail risk with any storms that get going in this region. Will need to watch along the CAPE gradient as well near I-90 if any storms can develop along this as shown in the HRRR/NAM Nest solutions as there would be more shear in play which would favor elevated supercells at convective initiation with a subsequent hail risk.

Overnight the aforementioned quasi-stationary boundary lifts very gradually north as a surface low over the Great Plains shifts towards the region. This will allow a more robust axis of MUCAPE to shift north towards I-90 corridor ahead of an approaching cold front from the west associated with the aforementioned surface low. As this cold front approaches the local area towards daybreak, much of the CAMs agree on initiating a secondary round of convection with this frontal passage. Overall, hodographs in the unstable layer are less elongated as earlier in the night so would expect more tendency for storms to trend multi-cellular to linear in this regime with large hail still being the predominant threat due to steep mid-level lapse rates and larger MUCAPE values.

Wednesday - Friday: Much Cooler, Mid-Week Wintry Mix Potential

After this aforementioned cold front passes through the area on Tuesday, temperatures take a noticeable dip into the middle of the week with highs generally in the 30s and 40s for Wednesday and Thursday. As we head into Wednesday night and Thursday, the next system that we will need to monitor moves towards the region in the form of a shortwave trough coupled with a developing surface low in the exit region of this shortwave. Compared to yesterday, there seems to be much more agreement amongst deterministic models for the path and amplification of this shortwave. Overall conceptual model with the system would have a surface low developing south of the local area with a robust deformation band on its northwest flank. Within the deformation band both the NAM/GFS have a decent axis of 700- 800mb frontogenesis into Thursday morning. Pretty strong warm advection pushes into the area aloft ahead of this low which establishes a decent warm nose aloft in the NAM/GFS soundings. The main questions with this is 1) How strong is this surface low and northerly warm push and 2) What is the exact location of this surface low. These questions will dictate how precipitation types and how amounts will manifest at any given location.

When looking at the cluster analysis of the grand ensemble (GEFS/EC/Canadian ensemble) each cluster group encompassing all members now have respectable probabilities (40-70% chance) for an inch or greater of snowfall in the local area, with some question on the southern extent. What is equally of interest is now a freezing rain footprint with medium probabilities (30-60%) for a glaze of ice is present in all cluster groups with again deviations on the exact location in the local area. So even if the deterministic models (NAM/GFS) have some eye catching freezing rain amounts in the region, still quite a bit of uncertainty on where and to what extent any icing threat materializes at this point. In any case, certainly a system to watch with increasing confidence that some level of winter precipitation will be present in the region, however questions remain on exactly how impactful. Also important to note that regardless of precipitation type, the EC Extreme Forecast Index has a fairly impressive footprint for anomalous QPF with high confidence (70-90%) to exceed EC model climatology with a shift of tails of 0 to 1 which is driven by the most extreme EC members having between 2 to 3 inches of QPF.

This Weekend:

As we head into this weekend, deterministic guidance uniformly agrees on swinging a deeper and broader trough through the central CONUS and towards the Upper Midwest. As a result, grand ensemble (GEFS/EC/Canadian ensemble) has very high probabilities (80-90%) for measurable QPF during this period. Given that there is some upper- level ridging that moves into the area for Friday, some moderation in temperatures will likely occur so current indication based on this and current progged track would favor a mostly rain solution for the local area at this time.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 103 AM CDT Mon Mar 30 2026

VFR expected through the 30.06Z TAF period. MVFR-IFR may shift southwest into central and western Wisconsin near the end of the period.

CLIMATE

Issued at 1248 AM CDT Mon Mar 30 2026

Near record highs Today (Record/Forecast):

Rochester, MN 77 (1967) / 74 La Crosse, WI 80 (1910) / 76

ARX WATCHES/WARNINGS/ADVISORIES

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