textproduct: La Crosse

KEY MESSAGES

- Strong to severe storms this afternoon and evening, mainly along and east of the Mississippi River. The main hazards will be large hail and damaging winds with a low but non-zero tornado threat.

- Temperatures gradually warming into the weekend

- Hot and humid conditions expected Sunday through mid next week with triple digit heat indices looking more probable (40-70%)

DISCUSSION

Issued at 205 PM CDT Wed Jun 24 2026

Today: Strong to Marginally Severe Storms

Isolated to scattered storms have popped up across the Upper Mississippi River Valley early this afternoon. Thus far, much of the activity has been rather pulse-like in nature: coming down almost as quick as they're going up. A few have been able to sustain themselves for longer than 15-30 minutes and have been able to produce some dime size hail. As the atmosphere continues to destabilize this afternoon, forcing will only continue to push further east with a cold front at the surface and a short wave trough in the mid/upper levels draped across the Upper Midwest. 24.17 RAP analysis suggests 1000+ J/kg of MLCAPE already present across the area with effective shear around 30-40 kts. So far it seems the modest shear has been what's holding the activity back but as this increases over the coming hours, an increase in supercellular structures will be possible. The main hazard with any storms today will likely be large hail given the seasonably cool temperatures aloft, even though lapse rates aren't particularly impressive. Damaging winds will be a possibility, especially on the southern end of the risk area (southwest Wisconsin) with drier air in the mid/low levels leading to slightly higher levels of DCAPE. While the tornado threat looks pretty low overall given the straight hodographs (meaning splitting cells are more likely overall) and decently high LCLs, some weak low level helicity could lead to a brief spin up this afternoon. The threat for strong to severe storms shifts to the east through the evening hours as the frontal boundary and shortwave push off towards the Great Lakes.

Thursday - Saturday: Warming Up

Generally benign conditions expected for the end of the week and into the early portions of the weekend. Upper level flow will turn zonal with weak surface high pressure sitting over the Upper Midwest. This high pressure looks to keep a stationary front to our south Friday into Saturday. Temperatures through this time period will be on an upward swing in the upper 70s to mid 80s by Saturday. Dew points will also be on an upward trend with mid 50s Thursday and Friday and upper 50s to mid 60s on Saturday. And it only gets worse from there...

Sunday - Early Next Week: Hot and Humid

A longwave trough is expected to deepen over the Western CONUS this weekend. In response, a high amplitude ridge is expected to build from the Lower Mississippi River Valley into the Upper Midwest and Great Lakes by Sunday into Monday. With it, a surge of warm gulf air will surge north. The 850 mb thermal ridge will also set up across the northern plains with 850 mb temps on the order of 10-15 deg C above normal for early summer. As such, surface temperatures will soar into the upper 80s to mid 90s with dew points in the upper 60s to mid 70s. This could lead to triple digit heat indices and the need for heat headlines. The heat is expected to linger into at least mid week with chances for rain each day as shortwave impulses traversing the ridge interact with the abundant moisture across the area. Whether these storms will be strong to severe is unknown as significant uncertainty with this activity remains.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 634 PM CDT Wed Jun 24 2026

Showers/storms have largely moved east of the area this evening with a few lingering cells possible north of I-94 through ~03z. Elsewhere, some gusty west to northwest winds to around 20KT may continue over the next few hours along with diurnally driven cumulus before diminishing with sunset.

Overnight, light west to northwest winds generally 10KT or less take hold across the region with primarily VFR conditions. However, MVFR to potentially IFR (20-40% per the 24.18z REFS) ceilings are expected along and north/northeast of I-94 early Thursday. These ceilings should lift and scatter through the morning hours with another period of diurnal cumulus around 5kft expected to develop areawide by late morning/early afternoon.

ARX WATCHES/WARNINGS/ADVISORIES

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