textproduct: La Crosse

KEY MESSAGES

- Showers move through late tonight into Tuesday morning with rainfall amounts generally under a tenth of an inch.

- Stronger winds develop through the night, gusting to 25-35 mph by sunrise. There are hints that winds in and around some of these showers may contain wind gusts of 50-60 mph, but details on timing and location of these gusts are difficult to pin down at this time.

- After a brief cool down for the middle part of the week, warmer weather returns for the end of the week and the weekend along with the risk for more robust showers and storms.

DISCUSSION

Issued at 150 PM CDT Mon May 11 2026

Tonight - Tuesday Morning: Showers, Stronger Winds

A band of showers arrives later tonight, driven by increasing warm air advection/isentropic ascent and a 50-60-kt LLJ ahead of an approaching cold front. An appreciably dry noctural airmass will be in place ahead of these showers, likely resulting in some erosion/evaporation of the leading showers, but the strength of the lift should eventually overcome this dry layer. Rainfall amounts should generally be < 0.10", though some locations north of I-94 could pick up a little more rainfall if the profiles can moisten fast enough (20-30% chance). These showers depart by mid to late morning.

The synoptic wind fields increase steadily through the night as the pressure gradient tightens ahead of the cold front, with the gradient maximized over the region around sunrise. A solid noctural temperature inversion should keep the wind gusts at bay, but higher elevations could still see gusts in the 25-35 mph range at times.

One big question revolves around the winds near and just behind the showers that move through in the early morning. The HRRR/RAP/ARW are showing pockets of stronger wind gusts, up to 50-60 mph, near or just behind these showers in a region of strong mesoscale subsidence--not too dissimilar to a wake low-- aided by a mid-level dry slot cutting into the backside of the line. As is to be expected, the location of these gusts vary considerably in space and time between model runs and likely won't show their hand until later tonight. The +12C warm nose will be in place at 850 mb that would act against the wind gusts, but the explicit signals in multiple CAMs for these winds certainly gives one pause if trying to fully discount them on account of the inversion. Bottom line, stay weather aware and secure any loose objects that might be blown around.

Tuesday Afternoon - Wednesday: Cooling off

Stronger winds linger through the day on Tuesday as the cold front passes through, with highs being reached by early afternoon before plateauing and starting to fall later in the afternoon as the lower tropospheric thermal ridge shunts off to the southeast. The region will be on the western edge of the 700-500-mb low that tracks over the Great Lakes in the afternoon and evening hours, with low stratus likely cutting across mainly Wisconsin into Wednesday morning. The surface ridge slides through Wednesday evening/night, setting the stage for possibly our last cool night for some time. Lows fall into the lower 30s towards central Wisconsin and will probably require a frost advisory for favored locales.

Friday - Sunday: Warming Up, Periodic Storms

Warm air advection starts in earnest Thursday and continues into Friday. Highs on Friday will be driven by the degree of showers that develop within the warm air advection regime ahead of a highly modified cold front that passes through later in the day. Warmer and muggier air surge northward through the weekend and set the stage for more rounds of storms Saturday or Sunday, but differences creep into the synoptic guidance by this time and make pinning down any specifics more difficult. While the 6-hourly PoP forecast has mentionable precip values for nearly every period of the weekend, the deterministic models show that the precip will be more targeted with drier periods, it is just a question of when these drier periods occur.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1233 PM CDT Mon May 11 2026

Primary concern over the next 24 hours centers around a 45-55 knot southwesterly low level jet that looks to develop overnight. This will lead to low level wind shear in the sfc to 1000 foot layer across much of the region. Light showers also look to sweep through the area at this time and these may (25%) bring down the stronger winds, leading to gusts up to 45 knots at the surface. While confidence was not high enough for explicit inclusion of these strong surface gusts in the TAFs, may need to include this in subsequent cycles. Otherwise, expect mainly mid-level cloud bases around 10 kft with winds, initially out of the southeast, becoming out of the west by the end of the period.

ARX WATCHES/WARNINGS/ADVISORIES

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