textproduct: La Crosse

KEY MESSAGES

- Slightly above normal temperatures expected today cease by midweek with cooler, below normal temperatures returning. Frost potential for some Monday through Thursday nights.

- Precipitation/meager storm chances Monday afternoon/evening with low rain chances returning by Thursday afternoon. Otherwise generally dry conditions areawide

DISCUSSION

Issued at 154 PM CDT Sun May 3 2026

Tonight - Monday: Fire Weather and Storm Potential

Winds have started to shift to the northwest across the region behind a weak cold front earlier this morning that brought a few light showers. Northwest winds will continue through the afternoon, bringing in some slightly drier air to the low levels. This will allow afternoon RHs to fall to between 25-35 percent across the region. Winds quickly shift back to the south overnight tonight ahead of a surface low just north of the US/Canada border with a trailing cold front. This front is expected to sag south through the local area tomorrow afternoon. Just how quickly it does so will play a factor into if we see any storms across our southern/southeastern counties. If this front is a bit slower like the 03.12 NAM solutions, we could see a few storms pop up along and south of the boundary tomorrow afternoon given some elevated CAPE in the 250-750 J/kg range and cooling temperatures aloft with steep mid level lapse rates. Any storms would be elevated in nature given that the southerly pre-frontal flow will likely not be able to wholly overcome the dry airmass already in place (forecast LCLs should be at or above 5000 ft based on model soundings). However, if the front is more progressive like the 03.12 HRRR, then our local area is not likely to see much in the way of convection with the front effectively wiping out the minimal moisture and instability in place. In any case, storms are not expected to be overly potent with a Day 2 Marginal Risk in place for portions of NE Iowa and SW Wisconsin.

Areas behind the front (SE Minnesota and WC Wisconsin) could see some elevated fire weather concerns as northwesterly winds ramp up by mid afternoon. RHs will again be in the 25-35% range but would not be surprised if these dropped a little lower given the potential for efficient mixing post-front. Given how wet of an April we had, fuels are not particularly primed for fire concerns at this point but it will be something to keep an eye on for tomorrow.

Tuesday - Next Weekend: Cool with Low Rain Chances

An unsettled but relatively benign pattern looks to take hold for much of the week with a strong upper low rotates around Ontario and the Hudson Bay. This will allow some shortwave troughs to sweep across the west/northwest flow aloft but surface high pressure and overall weak moisture return will prevent any large scale rain chances. Some afternoon diurnal showers/storms will be possible later in the week (Thursday and Friday) as we lose the influence of the surface high but currently not expecting much out of this activity. The persistent northwest flow will also keep temperatures from warming too quickly with highs generally in the 50s and 60s through the end of the week. Temperatures don't start flirting with the 70 degree mark again until next Saturday. Low temperatures and light winds Tuesday through Thursday morning could lead to some frost potential but current forecast temperatures do not support any additional hard freezes over the coming week.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 643 PM CDT Sun May 3 2026

Other than addition of LLWS to KLSE TAF site early Monday morning, similar ongoing VFR conditions expected through the 04.00Z TAF period. Previous night's observations and expectations of enhancement to nocturnal low level jet with light valley winds raises confidence in reaching threshold for a short time before daytime mixing through daybreak Monday.

Winds strengthen through Monday morning, initially southwest returning to northwest through the afternoon. Low (<25%) probability in light precipitation through the late afternoon into early evening for southeastern 2/3 of the forecast area, grazing KLSE TAF site, primarily affecting smaller airports from northeast Iowa into southwest Wisconsin. Accompanying aviation impacts appear minimal at the current forecast hour however MVFR ceilings or visibilities may be realized where precipitation occurs.

ARX WATCHES/WARNINGS/ADVISORIES

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