textproduct: La Crosse

KEY MESSAGES

- A linear mesoscale convective complex capable of producing damaging winds will likely move southwest and south of the forecast area late tonight and Thursday morning.

- Heavy rain will be possible along and south of Interstate 90 from Thursday into Saturday.

DISCUSSION

Issued at 154 PM CDT Wed Aug 12 2026

Tonight and Thursday

The 12.12z models are in general agreement that a shortwave trough, currently located over eastern Idaho and central Montana, will move east across South Dakota and Nebraska this afternoon and evening. As this occurs, scattered showers and storms will develop. With 0-6 km shear over 40 knots, some of these storms will become supercellular. As the evening progresses, the cold pools will coalesce and a linear mesoscale convective complex will develop on the nose of a 30-40 knot low-level jet. Wind gusts could be in the 60 to 80 mph. At this time, it looks like these winds would be southwest and south of the area overnight and southeast of the area on Thursday morning.

Low temperatures will be in the lower and mid-60s tonight. High temperatures will range from the mid-70s to mid-80s. The cooler temperatures will be along and south of Interstate 90 where there will be a better chance of showers and storms from late tonight into Thursday.

Thursday night into Saturday

2 to 3 shortwave troughs will move along the northern periphery of a 500 mb ridge centered over the western Gulf. In addition, a stationary front will linger across northern Iowa, southern Wisconsin, and northern Illinois. Surface-based CAPES will range from 2000 to 3500 J/kg south of this front. With precipitable water values will range from 1.5 to 2.25 inches along and south of Interstate 90 and warm-cloud layer depths around 4 km, heavy rain will be possible. From Thursday night into Friday south of Interstate 90, there is up to a 30 percent chance for 1 inch or greater and up to a 15 percent chance for 2 inches or greater. With weak 0-3 km and 0-6 km shear, not anticipating any organized severe weather.

High temperatures on Friday and Saturday will range from the mid-70s to lower 80s. Low temperatures on Thursday night and Friday night will range from the mid-50s to mid-60s.

Saturday night into Sunday night

The models are continuing to trend more and more south with the frontal boundary. As a result, the rain chances were reduced some. If this trend continues, we may have to eventually remove the rain chances.

High temperatures on Sunday will range from the mid-70s to lower 80s. Low temperatures will be in the lower and mid-60s on Saturday night and range from the lower 50s to lower 60s on Sunday night.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 154 PM CDT Wed Aug 12 2026

A lack of overall surface or near surface smoke impacts resulted in removal of previous mention for 12.18Z TAF issuance. Therefore, subsequent impacts will be low potential for Fog (30%) overnight into Thursday morning and subsequent storm chances moving west to east shortly thereafter. Highest local probabilities expected along and south of Interstate 90, therefore south of local TAF (KLSE/KRST) sites at the current forecast hour. Additional fine tuning will be required in coming forecasts as northern extent of storm chances becomes increasingly clear.

ARX WATCHES/WARNINGS/ADVISORIES

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