textproduct: La Crosse

KEY MESSAGES

- One last night of widespread near to below freezing temperatures before a warming trend sets in.

- A passing front Tuesday morning brings with it the next chance of showers to the area, but impacts and rainfall amounts look to be low.

- Warmer for the middle to end of the week with low 80s for highs possible for the weekend.

DISCUSSION

Issued at 100 PM CDT Sun May 10 2026

Tonight: Frost/Freeze Details

Surface high pressure and clear skies build southeastward from the Red River Valley of the North into Wisconsin between this afternoon and Monday morning. Coupled with a dry polar airmass featuring dewpoints in the low to mid-20s, the stage is set for yet another night of near to below freezing temperatures. Lows in the low to mid-20s are expected in favored low-lying and bog locations in west-central Wisconsin--similar to last night--with lows in the low to mid-30s throughout the rest of the forecast area. With ground temperatures having warmed up into the 40s to low 50s, impacts from these colder temperatures may be more acutely felt on trees versus plants at the ground level in areas where temperatures are closer to the freezing mark.

After today, we will have one last round of potential frost concerns to contend with Wednesday night towards central Wisconsin before the pattern shifts. Wednesday night notwithstanding for some locales, this might be the last widespread frost/freeze risk for the season if the medium to longer range solutions pan out.

Tuesday: Passing Band of Light Showers, Warmer

A compact shortwave/katafrontal setup arrives for late Monday night/Tuesday morning with the risk for showers confined to a relatively narrow corridor of lower tropospheric isentropic ascent ahead of the cold front. Moisture quality is questionable and weak at best and appears to be driving the differences between the GEFS/CMC and EPS models with respect to rainfall coverage and amounts, with the former pair of ensembles much drier than the EPS.

Given the modest upglide and 60-kt LLJ present and how any increase in 800-700-mb moisture would foster an increase in upright instability in the currently dry solutions, have kept 40-70% PoPs with the frontal passage--highest north of I-90. Either way one slices the forecast, given the progressive nature of the system and lack of available moisture, QPF amounts are shaping up to be around a tenth of an inch or less with the LREF probabilities of seeing over that amount less than 20-30%. Some diurnal showers may affect parts of central Wisconsin in the early to mid afternoon before drier air infiltrates the region through the afternoon.

The 925-700-mb thermal ridge does not pass through until mid to late morning, allowing for a rapid rise in temperatures during the morning before readings level off or even fall slightly in the afternoon. Given the narrow window for this to occur, there is naturally some uncertainty with the exact high temperature values for the day. This issue is most notable with some of the Mississippi River valley sites that have as much as a 10 degree difference between the NBM MaxT and hourly T grids owing to the effects of downsloping as winds switch to the west. Did force the NBM diurnal temps to match the MaxT for the day, but this aspect of the forecast may need refining.

Rest of the Week: Warming and Mostly Dry

The effects of the cold front passage on Tuesday afternoon will be short-lived. Highs in the mid-60s on Wednesday give way to the mid-70s on Thursday and then the low 80s on Friday as the synoptic pattern shifts and southwesterly flow ensues with the passage of a longwave ridge axis. The longwave pattern evolution becomes less certain for the weekend as several shortwaves flatten the ridge, with the potential for more robust storms possibly driving the warm sector southward for times during the weekend. The NBM interquartile high temperature spread by the weekend is 10-15 degrees with a 30 degree spread between the max and min members, reflective of the wider range of potential temperature outcomes.

As alluded to in the previous paragraph, dry weather prevails for Wednesday and Thursday as surface ridging translates through the region. Multiple rounds of storms then creep into the forecast for Friday into the weekend. The severe weather threat looks low at this time given the northward displacement of the polar jet, but the lack of steering flow could result in heavier rainfall with any of these storms. Exact rainfall amounts and timing will be hammered out as we go through the week.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1225 PM CDT Sun May 10 2026

VFR conditions are expected over the next 24 hours. Field of cumulus in the 5-10 kft range is present at issuance and will continue over the next several hours. Next disruptions look to occur around 06z to 12z Tuesday when SHRA and perhaps TS may occur.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Frost Advisory from midnight tonight to 8 AM CDT Monday for WIZ032-041-053>055-061. Freeze Warning from midnight tonight to 8 AM CDT Monday for WIZ017-029-033-034-042>044. MN...Frost Advisory from midnight tonight to 8 AM CDT Monday for MNZ079-086>088-094>096. IA...Frost Advisory from midnight tonight to 8 AM CDT Monday for IAZ008>011-018-019-029-030.