textproduct: La Crosse

KEY MESSAGES

- Temperatures warm up into early next week with highs in the 60s for Sunday and upper 60s to mid 70s for Monday. Temperatures cool back down into the 50s for midweek.

- Low rain chances (generally between 20 and 40%) for tonight. Another widespread rain chance for Monday afternoon and evening (25 to 50%). Periodic showers for latter half of next week.

DISCUSSION

Issued at 133 PM CDT Sat May 2 2026

Warming into Early Next Week:

A longwave trough will continue to sit over the Upper Midwest through the forecast period. This allows for northwest flow aloft to remain in place. While the upper level pattern is northwest flow, through Monday, the lower levels will have southwest flow. This will bring warmer air further north and help to increase temperatures each day. High temperatures for today are in the upper 50s to low 60s. By Sunday, the highs are in the mid to upper 60s and for Monday they are in the upper 60s to mid 70s. This warm up is short lived as a shortwave comes down from Canada and switches the low level flow back to the northwest, which will decrease temperatures back into the 50s through midweek. More frost and freeze headlines may be needed, especially for Tuesday night and Wednesday night as forecasted lows are in the low to mid 30s with some locations getting down into the 20s along and north of I-94. The most recent LREF supports this possible solution as the probability for less than 34F is between 30 and 70% for areas along and north of I-90 with the higher probabilities in north central Wisconsin.

Precipitation Chances:

Periodic precipitation chances throughout the forecast period. The first is a weak shortwave that moves through this evening and overnight. CAMs are focusing the rain chances closest to the vorticity lobe associated with this wave. While there is a low chance (15 to 30%) for rain showers across the CWA, the vorticity maxima goes through southeast Minnesota, northeast Iowa, and far southwest Wisconsin. Due to this, have raised PoPs to 30 to 45% for these locations. The sub cloud layer is quite dry so even if showers due form, they may struggle to produce much in the way of QPF. Total rain accumulations with this first wave are only a few hundredths with some locations potentially seeing up to 0.1". One thing to point out is that with the vorticity maxima, this could lead to some more moderate rain rather than light rain, which could result in amounts more than 0.1". The HREF does give a 40 to 60% chance for greater than 0.1" across portions of northeast Iowa and far southwest Wisconsin.

The next widespread rain chance (25 to 50%) is Monday afternoon and evening when a cold front sweeps across the Upper Midwest. Theta-e advection builds in with the southwest winds during the afternoon, ahead of the cold front. This lift along with the near 1.0" of PWAT, will help to initiate convection. There looks to be enough instability (between 350 and 700 J/kg of MUCAPE, based on GFS) that thunderstorms will be possible. Other mid range models such as the NAM and RAP also build some instability. Similar to tonight, there is some dry air near the surface so some of the rain may not reach the surface. As the cold front pushes through, mid level winds (around 5 to 8kft) increase to 30 to 40 kts, so while it may not rain at a given location, gusty winds may be possible. Mostly dry conditions expected for Tuesday and Wednesday before more periodic showers are possible for Thursday and Friday.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1222 PM CDT Sat May 2 2026

VFR conditions are expected to prevail at both RST/LSE taf sites through the taf period. A weak system will move across the Upper Mississippi River Valley tonight. This will produce scattered to isolated showers across the area. Due to coverage of the showers...will leave mention of showers out of the taf. Winds are expected to be west to northwest through the taf period at 5 to 15 knots with gust possibly to around 20 knots.

ARX WATCHES/WARNINGS/ADVISORIES

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