textproduct: La Crosse

KEY MESSAGES

- A prolonged stretch of hot and humid conditions arrive for much of next week with daily heat indices in the 100-105 degree range for some or all of the area.

- Next chance for showers and storms comes Saturday night into Sunday, some of which could be on the stronger side.

- The risk for storms--possibly severe--beyond Monday becomes increasingly uncertain and tied to the strength of the cap and tracks of the previous storms.

DISCUSSION

Issued at 1241 AM CDT Sat Jun 27 2026

Today

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

Late Tonight through Sunday Night

As a warm front approaches northeast Iowa and southeast Minnesota late tonight and through the remainder of the area on Sunday and Sunday night, most unstable CAPES will climb up to 1000 J/kg. This will result in some elevated showers and storms. With weak 3-6 km shear, not anticipating any organized severe weather. As the elevated mixed layer moves into the area from the Central Plains, this will likely greatly reduce the threat for damaging winds and tornadoes due to a strong inversion between 850 and 600 mb. In addition as this layer warms, hail size will likely be reduced as it melts on its way to the ground.

High temperatures on Sunday will range from the upper 70s to upper 80s. Heat indices will be in the 80s north of Interstate 94 and be mainly in the 90s for the remainder of the area.

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 22 to 24C on Monday. These temperatures are 2 to 2.5 standard deviations above normal. This will result in high temperatures in the lower to mid-90s. With dew points in the 70s, heat indices would range from the 100 to 110. This could result in the necessity for an Extreme Heat Warning to be issued.

Monday night through Friday

The models continue to show that as a series of shortwaves ejecting out of the western longwave trough from Monday night through Friday. These shortwaves will move along the west and northwest periphery of a quasi-stationary upper level high centered over the Ohio and Tennessee river valleys and Mid Atlantic Region. With strong to very strong instability across the region, multiple MCSs could potentially impact the region. Severe weather could potentially occur, but this would 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 through Friday. Of course, this will ultimately depend upon the convection from Wednesday into Friday. With higher confidence on Monday and Tuesday, we are planning on issuing an Extreme Heat Watch for this period for parts of the area.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1245 PM CDT Sat Jun 27 2026

VFR conditions are expected through the afternoon with fair weather cumulus occurring around KLSE. Gusty southeast winds will be continuing through much of the period, and especially on Sunday, ahead of approaching low pressure. Expect cloud cover to increase on Sunday, with scattered showers and MVFR cigs arriving to KRST in the morning. These showers will be associated with a weakening thunderstorm, with some indications that KRST could largely remain dry. Therefore, these morning showers are only around a 25-30% chance.

CLIMATE

Issued at 1241 AM CDT Sat Jun 27 2026

With 850 mb temperatures 2 to 2.5 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 from Monday into Wednesday.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Extreme Heat Watch from Monday afternoon through Tuesday evening for WIZ029-032>034-041-042-053>055-061. MN...Extreme Heat Watch from Monday afternoon through Tuesday evening for MNZ079-086>088-094>096. IA...Extreme Heat Watch from Monday afternoon through Tuesday evening for IAZ008>011-018-019-029-030.