textproduct: La Crosse

KEY MESSAGES

- Several rounds of severe storms for the remainder of the week, bringing the risk for mainly damaging winds and heavy rain. The main time periods for severe weather in the next 24 hours are early this morning and again later this afternoon and evening.

- Warm and muggy conditions persist for the remainder of the week, but heat indices will be slightly cooler than the start of the week and shifting to the south.

- More seasonable temperatures for the holiday weekend, though shower/storm chances exist (40-60%).

DISCUSSION

Issued at 1200 AM CDT Wed Jul 1 2026

Early this Morning: First Round of Storms

Another convective complex is progged to develop on the nose of a 30-40 kt LLJ in northern Iowa after 06-09Z and translate NE through the morning hours. Damaging winds will be the main concern with these storms quickly becoming outflow dominant and not last too long given the compact/complex hodographs but ample MUCAPE values of 1500-2000 J/kg. The recent CAMs are all depicting this feature in some way shape and form with the explicit gusts from the HRRR hitting 50-60 kts in small pockets from south-central MN into west-central WI. The other area of focus with these morning storms is if/where they lay out an outflow boundary that could modulate the threats and area of concern for storms later in the day.

This Afternoon/Evening: Round 2 of Severe Storms

Confidence is increasing that the morning convection will lay out a differential heating boundary from south-central Minnesota into west-central Wisconsin, but the devil is in the details as to its strength and position, which will feed into the behavior of storms later in the afternoon. The 01.00Z HREF guidance is targeting this boundary for convective initiation around 19-21Z, though in what form remains less certain. The ARW/NMM cores have the length of the line initiating in unison and growing upscale, while the HRRR holds the cap longer and rides more discrete convection along the boundary--a scenario that would increase the tornado and hail risk. This aspect of the forecast remains fluid and likely will remain as such until the midday hours when we can better assess the environment behind the morning convection.

No matter how storms form, they will be feeding on a favorable thermodynamic and kinematic profile with MLCAPE values of 2000-2500 J/kg and somewhat elongated hodographs that would support organized cell structures. Upscale growth into a bowing line segment is anticipated, but timing of this transition remains less certain. The tornado threat looks to continue with this upscale transition if bowing line segments can reorient themselves with the 0-3-km shear vector, though we'll have to see if there is localized backing of the 0-1-km wind field to further enhance this tornado threat.

In addition to damaging winds--which are the main threat with the afternoon convection--concerns are increasing about the possibility for multiple rounds of heavy rainfall in the evening and overnight. Boundary-parallel mid-level flow coupled with continued theta-e advection into the initiating front could result in training cells bringing pockets of 3-6 inches of rain in short order. In fact, all of the 01.00Z HREF guidance members have this corridor of higher QPF, but differ in 150 miles on its location between I-90 in southern Minnesota and I-80 in central Iowa. Thankfully, antecedent conditions are dry and we are entering a prime time in which cropland can better absorb such rains, but obviously such rains in urban locales and steeper topography could result in flooding.

Thursday - Friday: Severe Storm Risk Continues

The hits keep coming for Thursday and Friday with the lower tropospheric baroclinic zone wobbling across the region during this time, but more or less staying across the forecast area. This will serve as the focus for convective initiation as we go later in the week, but like a game of dominoes, one small deviation in storms earlier in the forecast can totally turn the forecast on its head in a hurry. One thing to watch for Thursday is how long storms later tonight persist, with a longer residence time towards morning possibly delaying or shifting the severe weather threat in the afternoon. Friday faces even more uncertainty in the timing and hazards with the convection, but the ingredients are all there, it is just a matter of how they are mixed.

Holiday Weekend- Early Next Week: Seasonable Temperatures With Additional Shower/Storm Potential

As the upper level pattern becomes more zonal as we head into the holiday weekend, several shortwave impulses are depicted to traverse the mean flow by the deterministic global models. These waves should result a reprieve from this week's heat as they usher in cooler air, slightly cooling temperatures towards the mid 80s, more seasonable for this time of year. Outside of the more seasonable temperatures, there is the potential for showers and storms throughout the weekend (40-60%), though these may shift more to the south depending on how Thursday and Friday's storms unfold.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1238 AM CDT Wed Jul 1 2026

There will be several rounds of storms through tonight. Used the CAMS to try add some timing to them. The first round will be likely around sunrise. Then there will likely be scattered supercells this afternoon followed by widespread convection for late this afternoon and evening.

CLIMATE

Issued at 127 AM CDT Wed Jul 1 2026

On June 30, the low temperature at La Crosse Regional Airport was 81F. This surpassed the previous warm low temperature record for the date of 78F in 1931.

This low temperature was the warmest June low temperature. The previous record was 80F on June 29, 1931 and June 22, 2025.

It also tied the warmest low temperature ever recorded in La Crosse. An 81F low temperature has occurred 4 times (July 21, 1901; July 13, 1995; July 4, 2012; and June 30, 2026).

ARX WATCHES/WARNINGS/ADVISORIES

WI...Heat Advisory from 1 PM this afternoon to 8 PM CDT this evening for WIZ041>044-053>055-061. MN...Heat Advisory from 1 PM this afternoon to 8 PM CDT this evening for MNZ096. IA...Heat Advisory from 1 PM this afternoon to 8 PM CDT this evening for IAZ008>011-018-019-029-030.