textproduct: La Crosse

KEY MESSAGES

- Low severe storm chances (<10%) tonight into early Wednesday afternoon.

- Temperatures gradually warming from Saturday through Monday.

DISCUSSION

Issued at 203 AM CDT Tue Jun 23 2026

This Afternoon and Tonight

A shortwave trough approaches the region this afternoon and moves through the Upper Mississippi River Valley and Great Lakes tonight. Multiple clusters of elevated storms over the Dakotas overnight and western Minnesota expected this morning. Some surface-based storms may work their way east into southeast Minnesota during the afternoon. As cold pools coalesce tonight, a line of showers and storms will move southeast through the region and into the western Great Lakes.

There continues to be much uncertainty on the amount of instability across the area due to the amount of convective debris clouds across the area this afternoon. Many of the models only have most unstable CAPES up to 250 J/kg. The most-unstable CAPES increase up to 750 J/kg tonight as the moisture plume ahead of the shortwave trough moves east into the region. While the 700 mb winds will be increasing into the 40 to 45 knot range, the orientation is not perpendicular to the line of the storms. This will likely reduce the damaging wind threat some.

Due to the convective debris clouds tonight, there continues to be some concern that the high temperatures for today may be too warm. We are currently forecasting high temperatures from the mid-70s to lower 80s. However, if the convective debris clouds are too thick, we may have to cool them closer to the NBM 10th percentile which has high temperatures ranging in the lower and mid-70s.

Wednesday

Another shortwave trough will move east through the region on Wednesday morning and early afternoon. Surface-based CAPES will likely range between 750 and 1500 J/kg and 0-6 km shear will be in the lower 40s ahead of this front. With cooling temperatures aloft, there may be some severe hail in southwest and central Wisconsin during the early afternoon.

High temperatures will range from the lower 70s to lower 80s. The warmest temperatures would be in the river valleys.

Thursday and Friday

Zonal flow will be found across much of the northern US. Depending on the timing of shortwave troughs, there may be a small chances of showers and storms. High temperatures will be in the lower and mid- 70s on Thursday, and in the mid- to upper 70s on Friday.

Saturday through Monday

As a longwave trough in the western US amplifies, an upper level ridge will build across the Upper Mississippi River Valley from Saturday through Monday. Depending on the position of this ridge, there may be some chances for showers and storms. High temperatures will gradually warm during this time period. They will range from the mid-70 to lower 80s on Saturday, in the 80s on Sunday, and range from the mid-80s to lower 90s on Monday.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 545 AM CDT Tue Jun 23 2026

Main aviation impact through the 23.12Z TAF period will be increasing storm chances from west to east initially later this afternoon and into the early evening, gradually becoming more widespread overnight. Potential weakening as initial storms progress east limits initial confidence at KLSE TAF site and therefore have continued with PROB30 mention until confidence in potentially more widespread storms progresses east into the nighttime hours. Also have accounted for a short break in between storms overnight in current TAF which will require further detailing in coming forecast (23.18Z).

Storm chances mostly exit east of the local forecast area through the overnight hours, potentially lingering east of the Mississippi River Valley locally affecting smaller airports in Wisconsin (e.g., K82C).

ARX WATCHES/WARNINGS/ADVISORIES

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