textproduct: La Crosse

KEY MESSAGES

- Temperatures gradually warming from Saturday through Monday.

- Heat Advisories will be likely needed for Monday and Tuesday and may be needed for Wednesday and Thursday during the afternoon and evening. Might even need an Extreme Heat Warning on Monday and Tuesday in some locations.

- Maybe some periodic severe weather from Monday night into Thursday.

DISCUSSION

Issued at 105 AM CDT Fri Jun 26 2026

Today and Tonight

An embedded shortwave trough in the zonal flow will move across northern Minnesota and northern Wisconsin today and upper Michigan tonight and another shortwave trough will move across Iowa this morning and northern Illinois and southern Great Lakes this afternoon and tonight. Surface-baased CAPES will be generally less than 200 J/kg. The best surface to 850 mb moisture convergence will be to our north and south. As a result, it is not surprising that the CAMs are mainly dry across the Upper Mississippi River Valley through tonight.

High temperatures will be in the mid- and upper 70s this afternoon and the low temperatures will be in the 50s tonight.

Saturday

A 500 mb ridge will slowly build across the area on Saturday. This will keep the area dry. High temperatures will be around 80 degrees.

Saturday night and Sunday

A warm front will produce scattered showers and storms as it moves northeast through the area on Saturday night and Sunday. With most- unstable CAPES less than 200 J/kg and weak shear 0-3 km and 0-6 km shear, not anticipating any organized severe weather. Low temperatures will range from the mid-50s to mid-60s. High temperatures on Sunday will range from the upper 70s to upper 80s.

Sunday night through Monday

As the western US trough digs, the upper level ridge will build northward toward Hudson Bay. Southerly winds will increase 850 mb temperatures into the 24 to 26C on Monday. These temperatures are 2 to 3 standard deviations above normal. This will result in high temperatures in the lower to mid-90s on Monday. With dew points in the 70s, heat indices would range from the 100 to 110. This could result in an Extreme Heat Warning.

Monday night and Thursday

The models continue to show that as a series of shortwaves eject out of the western longwave trough from Monday night through Thursday, the upper level ridge will gradually flatten. These shortwaves will be close enough that they will provide a chance for periodic showers and storms. With strong and and very strong instability across the region, some of these storms may become severe. This will be highly dependent upon the timing and the 0-3 km and 0-6 km shear.

High temperatures will range from the upper 80s to mid-90s. Heat indices will likely range from 100 to 110 on Tuesday and range from 95 to 105 Wednesday and Thursday. The confidence on the high temperatures and heat indices are lower due to the potential of showers and storm. If Wednesday remains similar to Monday and Tuesday, an Extreme Heat Warning may be needed even those the heat indices are lower. This is due to the longevity of this extreme heat.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 105 AM CDT Fri Jun 26 2026

VFR conditions are expected through the period. Some fog may develop in the usual trouble spots along the Wisconsin River (around OVS) but this should stay away from LSE. Cumulus is expected to return during the day Friday but this should be in the 3-5 kft range and should also remain at SCT or lower sky coverage.

CLIMATE

Issued at 105 AM CDT Fri Jun 26 2026

With 850 mb temperatures 2 to 3 standard deviations warmer than normal, there will be a potential for some warm low temperature records to be tied or broken south of Interstate 94 on Monday and maybe Tuesday.

ARX WATCHES/WARNINGS/ADVISORIES

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