textproduct: La Crosse

KEY MESSAGES

- Light rain showers are possible Saturday morning into the early afternoon (10-30%). Confidence in showers is highest north and east of La Crosse and south of I-90.

- Frost is possible again Sunday morning across Wisconsin with more widespread frost/freeze potential Monday morning.

- Higher rain chances develop Tuesday (50-80%), bringing around 1/4 inch of rain to the region. Temperatures then warm through next week.

DISCUSSION

Issued at 129 PM CDT Fri May 8 2026

Tonight - Saturday: Warmer and Mainly Dry

Northwest flow remains situated over the Upper Midwest this afternoon and tonight, allowing several shortwave troughs to meander through the region. The first of which moves through this afternoon and evening. Recent CAMs depict spotty sprinkle/shower development across the region, but overall confidence in this scenario is very low (<15%). While 08.15z RAP/HRRR soundings do depict saturation coinciding with forcing from the wave, they also depict an 8kft deep dry subcloud layer which will be very challenging to have hydrometeors fall through. If saturation ends up a little deeper, similar to what's depicted in the 08.12z NAM soundings, some sprinkles may be able to reach the surface but thinking any precipitation that falls will be realized as virga.

Higher confidence in light rain comes overnight into Saturday morning, primarily for those north and east of La Crosse, WI and south of I-90 as another wave and cold front move into the region. The dry subcloud layer is expected to erode ahead of this wave, with showers developing along the cold front over central Minnesota before moving southeastward into our area. However, forcing decreases as the area of showers moves in, so there is some uncertainty regarding coverage during the morning hours. The cold front continues shifting southeastward through the day Saturday with recent CAM runs developing showers across northeast Iowa into southwest Wisconsin (10-30%) given increasing low level saturation along 850hPa weak moisture transport and a lobe of 700hPa positive vorticity aloft. Outside of the isolated to scattered showers, dry conditions are expected.

Sunday - Monday: Mainly Dry, Morning Frost/Freeze Possible

Cold air advection behind the front that moves through Saturday ushers a cooler, drier airmass into the Upper Mississippi River Valley, resulting in overnight low temperatures falling into the mid to low 30s both Sunday morning and Monday morning. This brings the potential for frost conditions both mornings, although confidence is highest Monday morning. Subsidence associated with low level ridging should lead to clear skies and light winds overnight, resulting in a favorable set-up for efficient radiational cooling and more widespread frost/freeze conditions Sunday night-Monday morning.

Tuesday - Thursday: Rain Returns and Continued Warming

A deepening 500hPa shortwave trough dives into the northern Great Plains Monday, resulting in the development of a surface frontal system. This system translates east Monday night into Tuesday, dragging the cold front through the Upper Midwest. Probabilities for shower development along the cold front are already fairly high, currently sitting around 50-80% in the 08.13z NBM. While some variation exists regarding the placement of the surface low, which could play a part in how much rain is ultimately realized, the 08.13z NBM mean suggests amounts should end up around 0.2-0.3 inches with 10-30% to exceed 0.5 inches. The highest amounts, and highest probabilities for >0.5 inches, are currently expected mainly along and north of I-94. 08.12z GFS soundings also depict a few hundred J/kg of MUCAPE during this period which could lead to some rumbles of thunder, but the unfavorable morning timeframe should reduce any stronger convective development. Various bouts of southerly flow and low-level ridging should then lead to a warming trend as we progress through next week.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1223 PM CDT Fri May 8 2026

VFR conditions are expected through the TAF period although some low potential for light rain exists Saturday (10-30%). Those northeast of KLSE have the highest potential to see light showers Saturday morning while those south of I-90 are favored to see rain during the late morning to early afternoon. Impacts will be minimal, with the main impact being lowering cloud heights falling towards 4kft. Winds will be somewhat variable this afternoon through Saturday morning, but will be predominantly from the west to southwest around 10-15KT with gusts of 20-25KT west of the Mississippi River. Northwest winds then settle in for Saturday after 12z.

ARX WATCHES/WARNINGS/ADVISORIES

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