textproduct: La Crosse

KEY MESSAGES

- Periodic showers and thunderstorms are possible (20-50%) through Monday, mainly during the late afternoon and evening hours. Cannot rule out a severe thunderstorm for Monday but the chance is very low (<10%).

- The chance for periodic showers and thunderstorms decreases (10-15%) for Tuesday onward as a ridge builds over or near the area.

- Temperatures begin warming this weekend into next week with above normal temperatures favored from Sunday onward, particularly as the upper ridge builds Tuesday onward.

DISCUSSION

Issued at 151 PM CDT Fri May 22 2026

Periodic shower and thunderstorm potential through Monday

Upper trough, currently located over the northern Plains, will slowly churn northeastward through Sunday, with southwesterly flow aloft becoming quasi-zonal as a result. Multiple perturbations within this flow will lead to periodic windows with potential (20- 50%) for showers and thunderstorms. While uncertainty in timing of these perturbations is highest Sunday and Monday, enough consistency was seen across guidance to raise PoPs a bit during Saturday afternoon and evening.

As for hazards aside from lightning, progged CAPE profiles for Saturday and Sunday are skinny so think the chance for severe storms is remote. However, 22.15z RAP and 22.12z HRRR suggest a well-mixed boundary layer will be present, so cannot rule out a strong wind gust with any convection that does develop.

A bit more intrigue for Memorial Day as 22.12z GFS soundings depict robust CAPE profiles - around 2000-2500 J/kg of MLCAPE - and minimal capping, particularly north/west of a Charles City to Black River Falls line during the afternoon. That said, while deep shear values are enough for severe storms - around 30-40 knots - distribution of said shear in the vertical with little shear above 3km suggests convection may have trouble organizing with hydrometeors failing to vent away from their updrafts. Additionally, heights aloft look to be rising through the day which reduces enthusiasm with regard to the cap breaking. Furthermore, this overall scenario is largely present only within the 22.12z GFS and 22.00z GEFS, with ML- based guidance using ECENS keeping this potential away from our forecast area. Thus, while we should continue to monitor, overall thinking is that the potential for severe storms is pretty low (<10%).

Warmer temperatures, low rain chances Tuesday onward

Ridge aloft builds over the upper Midwest Tuesday onward. This will lead to temperatures well above normal with highs mainly in the 80s. Have tamped down 22.11z NBM highs, which included values in the low 90s on Tuesday, due to seasonal bias correction issues leading to a discrepancy of several degrees vs. LREF temperatures.

As for precip, 22.12z guidance seems to show more consistency in the placement and magnitude of the upper ridge compared to previous cycles. However, some ensemble members and 22.12z GFS show a ridge displaced a bit to the west, allowing for upper disturbances rotating around an upper low over Quebec/New England to pass over the CWA and potentially kick off some convection. Therefore, while warm and dry is the most probable outcome (80%) Tuesday through Friday, cannot totally rule out some disruption to outdoor activities at this time.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 656 PM CDT Fri May 22 2026

Ceilings generally 3-5kft continue this evening into the overnight hours with southeast winds beginning to wane towards 5-10KT. MVFR ceilings in the 2-3kft range move into the region from the west along a cold front that shifts eastward throughout Saturday. The 22.18z REFS and 22.19z NBM also suggest some probabilities for ceilings falling to around 1.5kft west of the Mississippi River (10- 30%). Also can't rule out some showers along this front, most favorable along and east of the Mississippi River (20-40%). However, coverage appears very isolated and impacts should be minimal, but did include a PROB30 group at KLSE to highlight the potential. With the passage of the cold front, ceilings begin to lift from west to east and winds veer to the northwest, resulting in VFR conditions returning for much of the region towards the end of the TAF period.

ARX WATCHES/WARNINGS/ADVISORIES

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