textproduct: La Crosse

KEY MESSAGES

- Showers and storms likely (50-95% chance) Tuesday evening and into Wednesday across much of the area.

- Cooler than normal temperatures through Thursday gives way to a warming trend into the upcoming weekend with highs returning into the 80s.

- Shower and storm chances (30-60%) return for the upcoming weekend.

DISCUSSION

Issued at 1140 AM CDT Mon Jun 22 2026

Tuesday - Wednesday: Showers and Storms Likely

The northwesterly flow that we have been experiencing over the past few days which has been responsible for our cooler than normal temperatures will advect a shortwave trough into the Northern Plains during the evening hours on Tuesday. As this occurs, an accompanying surface low will develop at the exit region of this feature with a surface cold front associated with it. As this surface feature approaches the area the local area later on Tuesday afternoon and into the evening, showers and storms will push into the local area with the highest probability (80-95% chance) for precipitation being near and north of I-90. Given the persistent forcing north of I-90 with the surface low pushing overhead and decent axis of 850mb moisture transport, could see some healthy rainfall amounts across portions of north-central WI. Currently, the NBM has high probabilities (60-80%) in north-central WI for rainfall amounts over 0.5" with even some probabilities (10-30%) for amounts over 1". However, given that precipitable waters would be around 1.2-1.3" (just under the 75th percentile of KDVN sounding climatology) as shown in deterministic guidance with marginal warm cloud depth, this should keep overly efficient rainfall rates to a minimum. Otherwise, cannot fully rule out a strong storm or two Tuesday evening and into Wednesday given there is some shear in play due to the stronger upper-level flow from the aforementioned shortwave. However, given the lack of instability progged in the GFS/RAP/NAM, with MUCAPE values struggling to even reach 500 J/kg across the area, this should keep any strong storm potential to a minimum.

Otherwise, temperatures will be fairly cool for this time of year during this period as both cloud cover and the passage of the cold front on Wednesday will aid in keeping temperatures in the 70s to lower 80s for much of the area. Any shower activity will generally exit by afternoon on Wednesday as the aforementioned surface low and upper-level wave push eastward.

Thursday - Friday: Drier, Cooler Than Normal

By the time the latter half of the work week rolls around, continued quasi-zonal flow and weak cold air advection behind the aforementioned front will keep temperatures on the cool side for Thursday with the inter-quartile range for highs in the grand ensemble (GEFS/EC/Canadian ensemble) keeping highs in the lower to upper 70s. However, as we head into Friday some warm air advection with an upper-level ridge will allow temperatures to increase slightly and set the stage for temperatures to warm up further into the weekend.

This Weekend: Warming Back Up, Storm Chances Return

The aforementioned warming trend continues into the weekend as the upper-level ridge begins to push eastward. The general synoptic evolution suggests a weak shortwave that pushes through the region early during the day on Saturday which may instigate some precipitation prior to the ridge moving overhead. Otherwise, warm air advection increases precipitation chances during this period as the grand ensemble (GEFS/EC/Canadian ensemble) has high probabilities (60-80%) for measurable rainfall on Sunday. The key question that remains is how models differ on how they handle a larger upper-level trough out west will translate earlier late this weekend and into early next week. The position of this trough by Sunday and into early next week will dictate any severe potential as it would be a prominent source of upper- level flow and deep-layer shear. As a result, much of ML/AI guidance paints much of the northern Plains and Upper Midwest in a 5 to 15% risk area for Sunday and Monday due to the uncertainty of where this trough will be positioned. However, keep in mind that this is several days out and many details will likely change. Nonetheless, certainly could be a period to monitor for a more active pattern should this trough push eastward more quickly.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1226 PM CDT Mon Jun 22 2026

Diurnal cumulus with bases around 4-5kft linger through the afternoon hours while light winds generally 10KT or less continue, predominantly from the north to northeast. Low level clouds dissipate with sunset while mid to upper level clouds move into the region from the west. There is some potential for fog again tonight, primarily for northeast Iowa into southwest Wisconsin but confidence in coverage is not overly high given the expected mid to high level cloud cover. That said, fog development will be most favorable in river valley locations across these areas, especially those along the Wisconsin River where the 22.12z HREF highlights a 20-40% probability for visibility of 1SM or less. Light and variable winds overnight shift to the south to southwest for Tuesday with the potential for precipitation increasing after the current TAF period.

ARX WATCHES/WARNINGS/ADVISORIES

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