textproduct: La Crosse

KEY MESSAGES

- Less smoke today

- Isolated to scattered storms tonight

- Severe weather possible late Sunday night/Monday morning and Monday afternoon and evening

DISCUSSION

Issued at 1247 AM CDT Fri Jul 17 2026

Early This Morning

As the warm front continues to move east through central and north- central Wisconsin overnight, scattered showers and storms will move east out of the area. In addition, the surface smoke should move east out of the area. The 17.00z HRRR looks to be a bit slow at reducing the smoke concentrations across the area, so used the warm frontal position to improve the timing of when this will occur.

As far as fog, the winds will be light not only at the surface, but up to 10k feet. The main question is how much low level moisture will located in the river valleys. Climatologically, dense fog would be highly favorable in the Wisconsin, the lower portions of the Kickapoo, and in the Mississippi tributary river valleys. This fog would likely start to develop between midnight and 4 am and dissipate between 7 am and 10 am.

Today

The models are in general agreement that high pressure will keep the area mainly dry. There are a few CAMs that suggest there might be a few isolated showers and storms in southwest and central Wisconsin during the mid to late afternoon. As a result, kept a 20 percent chance of rain in these areas. With little 0-3 and 0-6 km shear, not anticipating any organized severe weather. High temperatures will range from the upper 80s to mid-90s. Heat indices will be in the 90s.

Tonight

A longwave trough will move southeast through the area. As this occurs, a Canadian cold front will move south through the area. Surface-based and 0-1 km mixed-layer CAPES, quickly decrease ahead ahead of this front and the better 0-3 and 0-6 km shear stays off to our north and northeast. The CAMs are not overly impressive at this time, because they show a weakening line of convection moving into areas north of Interstate 94. This makes sense as the better forcing quickly moves east of the area with the longwave trough. Low temperatures will range from the mid-60s to lower 70s.

Weekend

Canadian high pressure will keep the area dry. High temperatures will be in the 80s on both days. Low temperatures on Saturday night will be in the mid and upper 50s in central and north-central Wisconsin and in the lower and mid-60s. There is some indication in the HRRR that smoke concentrations will be once again increasing on Saturday afternoon especially across Wisconsin. The winds aloft would favor that this smoke would linger across the area into Sunday.

Sunday night and Monday morning

The models continue to suggest that a mesoscale convective complex will move through the region late Sunday night into Monday morning. There is still plenty of uncertainty on where this system will ultimately track and its potential severity. The main severe weather threat would be damaging winds. Low temperatures will range from the mid-60s to lower 70s.

Monday afternoon and evening

A cold front will move southeast through the area. If we are able to recover from the morning convection (looking likely since we are in July), we could see a possibility of another round of severe storms. There is enough 0-6 km shear for some supercell thunderstorms to develop along and ahead of the front. A lot of this is dependent upon the strength of the cap aloft. If we keep cool air aloft in the wake of the morning convection, storms could continue to develop off an on all day. This would lower the severe weather threat. Now if there strong subsidence in the wake of the morning mesoscale convective complex, there could be strong capping aloft. This would allow for more instability to build ahead of the front. The question is when will the cap break. When it breaks, isolated to scattered supercells could rapidly develop with all hazards on the table. As the late afternoon and evening progresses, storms will likely congeal into a line with damaging winds and isolated QLCS tornadoes being the primary threats.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 551 AM CDT Fri Jul 17 2026

An isolated storm or two are possible in central Wisconsin over the next couple of hours. Some locations will continue to see patchy fog or smoke over the next few hours which has created reduced visibilities mainly in the MVFR range. Mostly dry conditions expected for the rest of the day until this evening when a broken line of showers and storms impacts areas mainly north of I-94. Smoke from the last couple of days is now mainly in central Wisconsin and points eastward. This smoke will lift off to the northeast throughout the day. Southwest winds of 5 to 15 mph today will switch to the northwest early Saturday morning as a front moves through.

ARX WATCHES/WARNINGS/ADVISORIES

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