textproduct: La Crosse

KEY MESSAGES

- Thunderstorms will move in across the forecast area early in the morning and some of the storms could be severe due to damaging straight line wind gusts.

- Periodic storm chances are possible throughout the rest of the forecast period along with cooler temperatures by this upcoming weekend.

DISCUSSION

Issued at 1240 AM CDT Tue Aug 11 2026

Now through This Morning: Storms and Severe Storm Potential

A few showers and storms developed earlier along a nearly stationary west to east boundary just south of the forecast area. As the boundary slowly trends northward, cannot rule out a couple attempts at convection over the next few hours across northeastern IA into southwestern WI. Given how the storms have largely struggled even with extreme buoyancy in place, there is very low confidence in any severe storm development through at least 3 AM. The lack of synoptic lift is likely leading to these storms struggling to become sustained.

The higher chance for severe storms is currently being forecast to occur across at least the southern half of the CWA starting near sunrise and lasting through at least mid morning. A complex of thunderstorms is anticipated to develop over eastern SD into MN/IA over the next couple of hours and quickly move east aided by upper level forcing. Unfortunately, timing and location of this potential system remains low confidence as CAMs have once again been very inconsistent with the evolution of a potential MCS. Sufficient instability and shear will be in place to sustain convection and form severe storms with the primary hazard being damaging straight line wind gusts up to 70-80 mph. Heavy rainfall may also lead to a threat for isolated flash flooding, especially for areas that receive rainfall before the main thunderstorm line moves through. Timing of the severe threat unfortunately remains uncertain, but in general storms should begin to move over the western counties by 5-8 AM and exit off to the east by 10 AM to 12 PM with some lingering showers or general thunderstorms into the afternoon hours.

This Afternoon Through Wednesday: Periodic Storm Chances

The area should be suppressed from any storm development this afternoon through the evening in the wake of the morning showers and storms. Cloud cover should clear out and temperatures are forecast to rise into the low to mid 80s this afternoon which are right at average for mid August. A rinse and repeat scenario may occur for Tuesday night into Wednesday morning as another shortwave trough quickly propagates east/southeast from the Dakotas towards the Midwest. The shortwave should trigger another round of showers or storms out of the Dakotas into Nebraska and they should quickly move east, potentially forming another MCS. Just how far east the storms can get remains uncertain at this time and may highly be dependent on how the storms pan out later this morning. Some outlier solutions do have another round of storms moving across MN/IA on Wednesday morning but confidence in the storms being severe or even reaching the area is extremely low at this point. Another warm day is likely on Wednesday along with mostly dry conditions. A surface boundary has the potential to set up over west central Wisconsin into central Minnesota which could become a focal point for afternoon into the evening storm development. Ingredients could be in place for severe storms should any storms develop along the boundary on Wednesday.

Thursday into Next Week: Trending Cooler with Continued Rain Chances

The center of the H500 high pressure is forecast to shift east over the Gulf coast states late this week into this weekend. The main ridge axis appears to stay south of the forecast area during this time frame which will keep the region underneath westerly flow aloft. This pattern should lead to cooler conditions Friday into next week with high temperatures a few degrees below average. Off and on chances for showers and storms is likely as shortwaves embedded in the upper level flow move over the Upper Mississippi Valley during this time frame. The highest chances (50-70 percent) for widespread rain are most notable on Saturday into Sunday as mid level moisture transport peaks as a stronger wave rounds the top of the ridge.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1240 AM CDT Tue Aug 11 2026

VFR conditions currently present across the region. An area of thunderstorms is expected to move in from the west/northwest during the early morning hours after 10Z. While the bulk of the potentially severe activity should stay to the south of the terminals in NE Iowa and SW Wisconsin, both the terminals will see a few hours of thunderstorm potential. As such, have transitioned the PROB30s from the earlier package to TEMPOs as confidence is now high enough that they will see this activity. This cluster of storms will move through during the morning hours with VFR conditions prevailing for the duration of the period afterwards. Winds through the day will remain light and variable.

ARX WATCHES/WARNINGS/ADVISORIES

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