textproduct: La Crosse

KEY MESSAGES

- Periodic showers and storms expected through mid-next week with high temperatures mainly in the 70s and low temperatures ranging from the mid-40s to mid-50s.

DISCUSSION

Issued at 211 PM CDT Thu Jun 18 2026

This Afternoon and Evening

A shortwave trough will move east southeast through the area. The combination of steep low-level lapse rates (up to 6.5 C/km) and the left-exit region of 40-45 knot 500 mb jet max has result into scattered showers and isolated storms along and north of the Interstate 90 corridor. These will continue through the remainder of the afternoon. Meanwhile, west of Interstate 35, it is right entrance of this jet which is aiding in the development of showers and isolated storms. These will affect areas south of Interstate 90 late this afternoon and evening. High temperatures will range from the upper 60s to mid-70s.

Friday afternoon and Friday night

Another shortwave trough will move through the region on Friday afternoon and evening. During the afternoon, lower to mid-50 dew points will spread northward across the Upper Mississippi River Valley. this result in surface-based CAPES climbing into the 500 to 1250 J/kg range and most-unstable CAPES of 500-1000 J/kg. A 45 to 55 knot mid-level jet will enhance the moisture transport and lift over the region from mid-afternoon through early evening. Temperatures aloft will be unusually cold (-18 to -21C at 500 mb) for mid-June. Finally, the 0-6 km shear will be favorable (40-50 knots) for the potential of supercell thunderstorms mainly along and south of Interstate 94. The main threats with these storms will be large hail and damaging winds. SPC currently has the area under a marginal risk for severe weather. This seems reasonable at this time. High temperatures will range from around 70 to the mid-70s.

Fathers Day

Another shortwave trough will move east through the region. This will result in another round of showers and storms. Unlike Friday, the instability is much less with most-unstable CAPES up to 250 J/kg. There are 2 strong jet maxes in the region. The first is located across Iowa and northern Illinois and the second extends from the Minnesota Arrowhead south into the northern Great Lakes. As a result, there is very little shear (less than 20 knots) across the Upper Mississippi River Valley. With little shear and CAPES, not anticipating any organized severe weather. High temperatures will range from around 70 to the mid-70s.

Monday Night into Wednesday

With zonal flow across the northern US, we will see several shortwave troughs move east through the region. These will bring periodic showers and storms to the area. It is too early to discern whether any of these storms will be severe. High temperatures will be in the 70s.

AVIATION /00Z TAFS THROUGH 00Z SATURDAY/

Issued at 635 PM CDT Thu Jun 18 2026

Showers and isolated storms continue moving east-southeast over the next few hours, moving out of the region around 03z-04z. VFR conditions then prevail overnight with west-northwest winds of 5-10KT. Shower and storm chances increase again early Friday afternoon (40-70%), continuing through the end of the TAF period areawide.

ARX WATCHES/WARNINGS/ADVISORIES

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