textproduct: La Crosse

KEY MESSAGES

- Highly conditional severe weather threat late Tuesday afternoon and night. If it does occur, the main threat would be damaging winds.

- Periodic showers and storms from Thursday night into Saturday.

- Mainly dry from Saturday night into early next week.

DISCUSSION

Issued at 1237 AM CDT Mon Aug 17 2026

This afternoon and tonight

As a shortwave trough approaches the area from the Northern Plains this afternoon, scattered showers and storms will develop across northern and western Minnesota. This convection will then move southeast into the area tonight. With the instability decreasing this evening, this convection will be on a weakening trend. In addition the 0-3 km and 0-6 km shear will be less than 20 knots, so not anticipating organized severe weather.

High temperatures will range from the mid-70s to mid-80s today. Low temperatures will range from the upper 50s to lower 60s tonight.

Tuesday and Tuesday Night

The models are in general agreement that a mesoscale convective complex will develop over eastern South Dakota, northwest Iowa, and southwest Minnesota during the overnight tonight and this system will either move east or southeast. This will greatly impact how much of the area is impacted. If the track of this system is more to our southwest, we will be able to build more instability prior to another shortwave trough on Tuesday evening. If this system tracks more east, much of the area will see rain-cooled air in its wake and in turn, there would be little recovery time prior to the Tuesday night shortwave trough. If there is a chance of severe weather late Tuesday afternoon and Tuesday night, the former solution would likely have to occur. The main severe weather threat under this scenario would be damaging winds.

High temperatures will range from the mid-70s to mid-80s on Tuesday. Low temperatures will range from the upper 40s to lower 60s on Tuesday night.

Thursday Night into Saturday

For late this week, the global and ensemble models are in general agreement that the western ridge will retrograde into the southwest US and then build north into the Rockies, Pacific Northwest, British Columbia, Alberta, and Saskatchewan. As this occurs, a series of shortwave troughs will carve out an eastern US longwave trough. These systems will provide a chance of periodic showers and storms from Thursday night into Saturday. While the 0-1 km mixed-layer CAPES climb up to 1K J/kg ahead of these shortwave troughs, the better 0-3 km and 0-6 km shear remain less than 20 knots. As a result, the threat for organized severe weather remains on the low side.

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

Saturday Night into Early Next Week

Canadian high pressures will build across the area during the upcoming weekend. It will provide dry weather and seasonable temperatures. High temperatures will range from the mid-70s to lower 80s and low temperatures will be in the 50s.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 524 AM CDT Mon Aug 17 2026

Intermittent IFR/LIFR valley fog at KLSE will diminish quickly this morning leaving VFR conditions for the mid-morning through early evening hours. Showers will be possible (20-40% chance) late this evening and into the overnight as a disturbance moves through the region. Consequently, have included a prob30 at both KLSE and KRST to address this low confidence potential. Otherwise, winds will begin the TAF period from the northwest at around 5 kts before shifting to southwesterly/southerly by the evening hours.

ARX WATCHES/WARNINGS/ADVISORIES

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