textproduct: La Crosse

KEY MESSAGES

- Showers and storms continue for much of the forecast area. Storms will move off to the northeast through the evening. Total rain amounts of 1 to 2" are possible in western Wisconsin with locally higher amounts possible. - Warm and muggy for Tuesday and Wednesday with highs in the mid to upper 80s for Tuesday and the mid 80s to low 90s for Wednesday. Heat indices in the low 90s for Tuesday and the mid 90s to low 100s for Wednesday

- Storm chances return for Tuesday night and again on Wednesday with confidence increasing for a severe weather event to occur on Wednesday afternoon and evening with large hail, damaging winds, and tornadoes possible. Another conditional threat for severe weather is possible for far northeast Iowa and southwest Wisconsin on Thursday. Stay tuned for forecast updates as there are still uncertainties.

DISCUSSION

Issued at 208 PM CDT Mon Jun 8 2026

Today: Scattered Showers and Storms

A shortwave continues to make its way through the Upper Midwest this afternoon and evening. MUCAPE values largely remain in the 500 to 1500 J/kg range. PWATs remain between 1.7 and 2.1" with dewpoints in the mid 60s to low 70s. Storm motions compared to Sunday are a little faster, however when looking at soundings for this afternoon and early evening, the warm cloud depth remains around 4km so the combination of this with the tall/skinny CAPE profiles indicate heavy rain potential. The 00Z HREF does highlight western Wisconsin with a swath of 1 to 2" for the mean precipitation amounts from now through the evening. In the LPMM, via the 00Z HREF, there are patches of 3 to 4" in parts of western Wisconsin. With warm rain processes ongoing, these values could very well occur. It all depends on how much training of storms we can get during the afternoon. It has been relatively dry in western Wisconsin so the ground could take a bit of rain before flooding concerns become an issue, however if storms do train over the same area, then localized flooding could occur. With all things considered, WPC has put much of southwest Wisconsin and central Wisconsin and portions of northeast Iowa in a slight risk for excessive rainfall.

Tuesday-Wednesday: Warm and Muggy, Storms Tuesday night and Wednesday

After this wave moves out early Tuesday morning, shortwave ridging arrives. This is the heat we have been talking about for awhile now, however it will not last long. Due to the trough sticking around for a little longer, southwest flow does not get going until the early to mid afternoon. This has brought down temperatures by a few degrees. NBM probabilities for 90F on Tuesday low (around 10 to 25%) across the CWA. Highs are looking to stay in the mid to upper 80s. Dewpoints also increase for Tuesday with upper 60s to low 70s expected. Due to the slightly lowered temperatures, heat indices have dropped as well, with most locations seeing the low 90s and some locations getting into the mid 90s. Heading into Wednesday, while southwest flow remains over the area and warm air advection increases, storms may inhibit how warm we get. Dewpoints increase once again by getting into the low to mid 70s. EFI values for Wednesday are between 0.7 and 0.9 indicating that these high temperatures are on the warmer side of climatology. Similar to Tuesday's probabilities and due to the uncertainty surrounding the storms influencing temperatures, NBM probabilities for at least 90F have gone down compared to the previous forecast with only widespread values of 20 to 45%. Forecasted highs stay mainly in the upper 80s to low 90s. As a result, heat indices have not changed a whole lot by staying in the mid 90s to low 100s. Again these values are a little uncertain depending on when storms form and if storms from the morning impact these temperatures.

Switching gears to talk about the storms. After a mostly dry Tuesday, a warm front lifts into the region late Tuesday evening and through the overnight. Instability builds in with this warm front with 2500 to 3500 J/kg of MUCAPE moving into the area for the overnight. While capping may be a concern, the low level jet increases during the overnight with 850mb winds of 25 to 35 mph. Confidence is increasing that storms could fire along this warm front and if they do, with the elevated instability available, large hail and gusty winds may be possible. These storms exit the forecast area by mid morning Wednesday.

By Wednesday afternoon instability builds in with SBCAPE values in the 2500 to 3000+ J/kg range. A cold front moves eastward across the Upper Midwest and as it does, deep layer shear values increase to around 40kts. Hodographs continue to show good low level curvature indicating that supercells could form initially. Storm modes are expected to change from supercells to a more linear mode that may have bowing structures. With these storm modes, all storm hazards will be possible. The timing for these storms based on the current guidance continues to be in the afternoon through the evening. AI and ML guidance continues to highlight our area for severe weather potential and SPC has highlighted our entire forecast area in an Enhanced (level 3 of 5) for severe weather. Even though the warm front that lifts north brings in a more unstable atmosphere, there is uncertainty on the extent of the severe weather due to the morning convection.

Thursday: Slightly Cooler, Conditional Severe Weather Threat

After the cold front passes through on Wednesday night, a low ejects out of the southern Rockies. This low moves off to the northeast towards the mid-Mississippi River Valley. There is better deep layer shear for Thursday and modest instability builds in. There is quite a bit of uncertainty on the path of this low and how much we can recover from Wednesday. The area of potential concern would be northeast Iowa and southwest Wisconsin as storms look to fire early in the afternoon ahead of another cold front. This front is stronger than Wednesday's and will play a bigger role in keeping temperatures in the mid 70s to low 80s. Overall, while storms will fire on Thursday afternoon, the location of these storms is uncertain due to exactly where any outflow boundaries set up from Wednesday and how much we can recover. The better severe weather threat remains to be on Wednesday but a threat for northeast Iowa and southwest Wisconsin could exist, and as a result SPC has a 15% or slight risk for severe weather for these locations due to the conditional potential.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 106 PM CDT Mon Jun 8 2026

Ongoing rainfall slowly shifting east, primarily affecting along the Mississippi River in the nearest term moving into central Wisconsin into the evening hours. Heavy rainfall will cause temporary IFR-LIFR visibilities where they set up.

Fog impacts appearing more likely area wide in wake of recent rainfall. Have introduced LIFR visibilities as a result at both local TAF sites (KLSE/KRST).

ARX WATCHES/WARNINGS/ADVISORIES

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