textproduct: La Crosse

KEY MESSAGES

- Our stretch of cold weather continues through the first half of the new week, with the coldest temperatures coming Monday night as lows crater into the teens. Temperatures rebound back to around normal for Thursday into next weekend.

- A couple passing shots of light rain or snow showers are expected this afternoon and Monday.

- Widespread rain starting Tuesday night and continuing off and on through the end of the week. The general setup doesn't overly favor the excessive rainfall amounts we saw over the last few days, but could still affect river levels.

DISCUSSION

Issued at 151 PM CDT Sun Apr 5 2026

Tonight - Tuesday: Colder with Light Precipitation Chances

A cold front, currently draped across Northern Minnesota is expected to move southeast into the area later this afternoon and evening. As it moves through, the low levels will saturate and allow for some light showers along the boundary. A few snowflakes could mix in across North Central Wisconsin if the profile cools enough but otherwise this precipitation should stay in the form of rain. Totals will be very light as this will be a shallow topped precipitation field. Did add some thunder mentions across Northeast Iowa as a shallow layer of elevated instability develops in this region. While it's only a couple hundred J/kg of CAPE, it's enough that a few rumbles of thunder can't be ruled out.

A much cooler airmass will drop in behind this cold front with temperatures Monday below normal in the mid 30s to lower 40s. As a weak upper level shortwave passes through the northwest flow aloft over the Northern Great Lakes, this will just clip our North Central Wisconsin counties. This looks like a classic northwest flow cold air advection cloud street snow shower type of event tomorrow afternoon as steep low level lapse rates develop at and below the DGZ. Accumulations will be minor and impacts outside of briefly reduced visibilities should be nil. These snow showers should gradually shift east of the area with dry conditions expected overnight. As skies clear and a surface high pressure moves into the region Monday night into Tuesday, a prime radiational cooling night should take shape with lows dropping into the teens to low 20s. 05.00 LREF Grand Ensemble probabilities show a 50-90% chance of low temperatures at or below 20 degrees. There are even some low probabilities (10-20%) of low temperatures in the single digits, though this is mainly confined to West/North Central Wisconsin. It isn't until the high pressure slowly drifts east through the day on Tuesday that we start to see some return flow and warmer air coming back into the region.

Tuesday Night - The Weekend: Multiple Rounds of Precipitation

In the upper levels, a wave is expected to dive southeast out of British Columbia Tuesday and ride the US/Canada border into the Upper Midwest Wednesday into Thursday. A surface low is expected to develop just out ahead of this and trek along a similar path through Thursday. With increasing moisture from the aforementioned return flow and isentropic lift ahead of the approaching wave, some light showers are expected to develop across the region Tuesday night into Wednesday. Current soundings show this starting off as a rain/snow mix before converting completely to rain with low level warm air advection making its presence felt. Then the cold front that trails the surface low to our north and east will move in later on Wednesday and reinforce chances for precipitation with the better focus for lift. This may also be able to tap into some elevated instability and create some chances for thunderstorms. Overall, QPF from the isentropic showers look to remain light at around a tenth of an inch. Slightly better QPF is expected with the line of showers and thunderstorms along the front thanks to more reinforced moisture and invigorated lift.

As the surface low moves northeast back into eastern Canada, the trailing cold front is expected to stall somewhere across the region by late week. Current guidance suggests this will be south of our area which has allowed for decreased PoPs late Thursday into Friday. In fact, a majority of both GFS and EC ensemble members have trended lower in their precip chances and QPF behind the frontal boundary late Wednesday. It isn't until the weekend that precipitation chances start to return en mass as the boundary lifts north and deeper moisture is able to make it's way into the Upper Mississippi Valley. This is because mid/upper level flow becomes more southwesterly, allowing for a northward surge of gulf moisture. There's still plenty of uncertainty regarding QPF as it will depend at least partly on the boundary. NBM 05.13 probabilities of 24 hour QPF greater than 1 inch peak between 30-40% across the region Sunday with precipitation expected to continue into early next week. Though the potential for significantly heavy rainfall from this event does not appear all that high at this time, it will need to be monitored as the forecast evolves for any potential hydrologic concerns.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1252 PM CDT Sun Apr 5 2026

Ongoing VFR expected to mostly hold through the evening into today as a band of increasing precipitation chances progressing northwest to southeast through the evening hours into tonight brings chances for MVFR/VFR ceilings. While main impact will be MVFR- IFR ceilings, may see some visibility reductions as line progresses as well. MVFR-IFR ceilings expected through Monday morning in the wake of the frontal boundary.

HYDROLOGY

Issued at 1252 PM CDT Sun Apr 5 2026

The dry conditions have allowed floodwater to progress downstream and cancellation of upstream Flood Warnings along the Kickapoo River in southwest Wisconsin. Expect similar through the start of the week as floodwater continue downstream.

Precipitation chances tonight expected to have limited impact as overall amounts <0.1" expected. Although, could see slight delay in crests or increase in observed heights temporarily.

Subsequent, widespread precipitation chances Tuesday night will be important to monitor as river levels expected to respond through Wednesday as heavier rainfall persists through midweek. Amount of recovery will be main forecast detail to monitor over the next 48 hours.

ARX WATCHES/WARNINGS/ADVISORIES

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