textproduct: La Crosse

KEY MESSAGES

- Shower and storm chances return Friday night into Saturday morning (30 to 60%). Severe potential is low (<10%) with these storms.

- Widespread rain is likely Monday (70 to 90%) with some potential (15%) for heavy rain and localized flooding concerns.

DISCUSSION

Issued at 150 PM CDT Thu Sep 10 2026

Thunderstorm potential returns Friday night

Friday into Saturday, upper low churning over northern Saskatchewan should usher a weak front south through the CWA. As this occurs, disturbance within the quasi-zonal flow aloft over the Upper Midwest will eject eastward, potentially (30-60%) leading to showers and a rumble of thunder. While shear appears supportive of severe thunderstorms, instability decidedly does not. Indeed, 10.00z LREF joint probabilities of sufficient shear, instability, and lack of CIN for severe storms are near zero. This is largely in line with the overnight timing of the upper disturbance, right in the right part of the day to expect issues with instability. Thus, while including rain in the forecast is prudent, am not concerned about hazards aside from stray lightning.

Rainy Monday with flooding potential

Sunday into Monday, strong upper wave moves over the Rocky Mountains to the northern Dakotas as ridging continues to be present in the southeastern CONUS. With lee pressure falls occurring across the High Plains, this will induce robust southerly moisture advection from the Gulf. By Sunday night, 10.00z LREF suggests PWAT values around 1.6" with potential (10%) for this to exceed 2". 10.00z guidance suggests precip will fall in 2 phases: 1) as WAA ramps up early Monday and a lead disturbance ejects northeastward over WI and 2) as the cold front pushes southeast during the evening. Locations that see moderate rain during both phases have a small chance (10-15%) to exceed 4" in rainfall with extreme outcomes across the 10.00z GEFS/ECENS/CMCE having over 7". Will need to monitor this closely, particularly if guidance trends toward a less progressive pattern with a lingering warm front, as those extreme outcomes would come into play more.

AVIATION /00Z TAFS THROUGH 00Z SATURDAY/

Issued at 622 PM CDT Thu Sep 10 2026

VFR conditions are forecast with this TAF cycle. Any fog that develops tonight is expected to remain in the river valleys across far southwestern WI and should not cause impacts at KLSE or KRST. The wind will slowly increase overnight, but moreso after sunrise tomorrow. The wind tomorrow should increase up to 10-15 kts with gusts up to 25-30 kts, particularly at KRST. Some mid level clouds may develop late in this TAF cycle, but cloud bases should remain well above MVFR thresholds.

ARX WATCHES/WARNINGS/ADVISORIES

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