textproduct: La Crosse

KEY MESSAGES

- Strong to severe storms are expected across the region primarily this evening into tonight. The primary hazards will be damaging winds and heavy rain.

- Additional showers and storms are possible Thursday afternoon (30-60%), but when/where they develop largely hinges on the evolution of storms tonight.

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

DISCUSSION

Issued at 205 PM CDT Wed Jul 1 2026

This Afternoon - Thursday Morning: Severe Storm Potential

A fairly challenging forecast riddled with uncertainty exists over the next 24 hours. Model guidance has largely struggled to resolve this morning's storms and the influence they'll have on the atmosphere as we head into the overnight hours.

Observational and satellite analysis suggests that a surface boundary exists generally from northeast Iowa into north-central Wisconsin, a slight southern shift from earlier CAM solutions, owing to outflow and cooling from this mornings convection. South of this boundary, an unstable airmass is in place across portions of northeast Iowa and southwest Wisconsin characterized by SBCAPE values exceeding 2500 J/kg below effective bulk shear values of 35-40kts. Differential heating and/or outflow boundaries that have developed during the day may provide enough forcing for storm initiation which could then pose a large hail and damaging wind risk given DCAPE values exceeding 800 J/kg and slight elongation in model hodographs.

This boundary is expected to be the primary catalyst for convective development this evening as a 500hPa shortwave trough moves overhead and a strengthening 850hPa low level jet extending northward from Nebraska nudges into the boundary. Given the slight southern shift to the boundary, current expectations are for convective initiation further south than previous forecasts, more in line with solutions such as the 01.12z ARW/NAMNest. However, how far south this boundary gets and/or if it shifts back northward (and thus the location of convective development) will be dependent on how much clearing we see over the next few hours.

Despite the slight changes in location, there has been little to no change from a hazard perspective. Given a boundary parallel 0-6km shear vector, expectations are for a more linear storm mode with damaging winds of 60-80 mph the primary threat although a few tornadoes cannot be ruled out within favorably oriented bowing segments. Any discrete potential will be favored with convective initiation along the boundary which would be more favorable for large hail and additional tornado potential.

Heavy rainfall potential continues to be a concern along and just north of the aforementioned boundary where storm motions along the boundary are favorable for training storms. High PWATs of 1.7-1.9 inches exist over Iowa this afternoon and will be advected into the boundary along the aforementioned low level jet which combined with warm cloud depths of 10-14kft should result in some heavy rainfall. An additional 1-3 inches of rain is possible (20-50%) with these storms with the 01.12z HREF LPMM even suggesting some areas could see 4-5 inches if conditions line up just right. That said, the southern shift of the boundary should result in these higher totals south of the highest rain axis seen with this morning's convection which would limit flooding risk over these areas.

Thursday Afternoon - Friday: Severe Storm Potential Continues

As if the last few days didn't have enough showers/storms, additional development is possible Thursday afternoon with the 01.13z NBM suggesting 30-60% probabilities for measurable precipitation. That said, a lot of disagreement exists between the short-term guidance regarding timing/location due to a lot of dependence on how storms evolve tonight/Thursday morning. The thermodynamic and kinematic environments do appear favorable for strong/severe storms if/when they develop (2000-3000 J/kg MLCAPE and 35-40kts of 0-6km bulk shear) although these parameters are slightly displaced from each other. Storm mode will largely be a function of where storms develop, but current expectations are for a more multicell-type mode given the displacement of instability and deep-layer shear.

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

Models continue to indicate a more zonal pattern developing across the United States as the ridge that's been in place this week breaks down and moves eastward. This will allow for several shortwave troughs to traverse the mean flow through the holiday weekend resulting in periodic shower/storm chances (50-70%). We're currently highlighted in a level 1/5 risk for severe weather on Friday July 3 by the SPC while AI/ML guidance highlights some low potential for severe weather on Independence Day. Apart from the storm potential, temperatures continue to trend towards normal with high temperatures in the mid 80s.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1229 PM CDT Wed Jul 1 2026

Showers and storms have been slow to clear out during the morning hours, leading to fairly low confidence in how an additional round of showers/storms evolves later this afternoon and evening. That said, most models continue to suggest this additional round of showers/storms moving through the region generally after 00z (50-80%) bringing MVFR/IFR ceilings and visibilities. Winds will be primarily from the south to southwest with gusts up to 25KT strongest west of the Mississippi River. Some potential for lower ceilings exists Thursday morning behind the showers and storms with the 01.12z HREF suggesting 20-40% probabilities for ceilings less than 3kft, scattering out through the afternoon.

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