textproduct: La Crosse

KEY MESSAGES

- Showers move through the region this morning with rainfall amounts generally under a tenth of an inch expected.

- Windy for today with winds gusting as high as 30 to 40 mph through the early evening hours. Wind gusts of around 50 mph cannot be ruled out (~10% chance) with showers this morning, however confidence is low in where/if this will occur.

- Temperatures cool down for the middle of the week with highs in the 60s and 70s. However, highs warm into the upper 70s and 80s by Friday with an increasing risk for showers and storms.

DISCUSSION

Issued at 1054 PM CDT Mon May 11 2026

Today: Windy with Showers This Morning

A fairly well pronounced shortwave will push through the region this morning and throughout the day as it crosses into northern MN/WI. As it pushes into the region, a fairly pronounced surface low with a tight surface pressure gradient will both note an increase in our winds during the morning as well as bring a round of showers into the local area. The main immediate question with these showers around sunrise will be how they interact with a rapidly increasing low-level jet at 850mb with the recent RAP having winds of 50-60 kts in this layer. This coupled with momentum transfer to the surface within any more robust showers may allow these winds to reach the surface. However, given the fairly robust dry layer and nocturnal inversion in place, it is unclear exactly to what extent this would occur. However, given these strong winds off the surface, cannot rule out some wake low potential on the back edge of these showers which could bring strong to locally damaging wind gusts. Overall the recent HREF only has low probabilities (10% chance) for wind gusts over 50 mph where showers occur, emphasizing that these may be more localized but still a tangible threat this morning. All said, while some of the CAMs have signal for these gusts to occur, it is not clear how this would interact with the inversion in place. As far as rainfall amounts are concerned, ensemble guidance is fairly unimpressive in part due to the aforementioned low-level dry layer keep precipitation rates on the lighter side. As a result, the recent HREF only has low to medium (10-50%) for rainfall amounts of 0.05" or greater during the morning hours.

As we head into the remainder of the daytime hours, the lessening of the nocturnal inversion will allow for diurnal mixing to mix down low-level winds of 30 to 40 kts across the area. As a result, expecting wind gusts to increase for much of the day to around 30 to 40 mph. Eventually, a cold front passes through the region later into the day shifting winds from southerly to northwesterly before winds will decrease as the aforementioned surface low begins to push eastward of the local area with the surface pressure gradient lessening overnight.

Wednesday - Thursday: Cooler, Light Shower Chances Late Thursday

As we head into Wednesday, subsidence on the back edge of the troughing regime will allow for surface high pressure to build into the region for the day. Consequently, expecting clearing skies and winds to gradually decrease by the time late afternoon and into the evening rolls around on Wednesday. Given the northwesterly flow regime, highs will be noticeably cooler for the daytime hours with the inter-quartile range in the NBM generally keeping highs in the lower 60s to lower 70s.

Surface high pressure moves directly overhead during the overnight hours on Wednesday. As a result, sky cover and winds will lessen considerably which in turn will allow for optimal radiational cooling. Where winds are more likely to become calm across portions of west-central WI, low temperatures in the 30s combined with these light winds will likely result in frost formation. Upper-level ridging and southerly surface flow on Thursday will allow for a warming trend to begin with highs returning into the 70s on Thursday. However, as some vorticity advection coupled with this warm advection regime moves through the local area on Thursday night, precipitation chances increase accordingly. Overall probabilities for rainfall over 0.1" are respectable (40-70% chance) within the grand ensemble (GEFS/EC/Canadian ensemble), however given the weaker forcing and minimal instability, rainfall amounts greater than this seem unlikely at this point.

Friday - Sunday: Warming Back up with Periods of Showers and Storms

By the time the end of the work week rolls around, warm air advection is in full swing with highs returning into the upper 70s to 80s for the area on Friday and into the weekend. For Friday and Saturday, the synoptic pattern favors a more quasi- zonal flow pattern with periodic shortwave perturbations in the flow. This coupled with southerly return flow will aid in increasing our dewpoints along with more favorable instability, the trouble that remains though is exact timing and exactly how far north the moisture push gets into the region during the weekend. Currently, ML/AI outlooks try to sneak some increasing probabilities for severe weather into the area south of I-90 for Sunday. However, remains fair to early to say how this would manifest as both deterministic and ensemble guidance still struggle to resolve any individual shortwave perturbation well. Regardless, the grand ensemble (GEFS/EC/Canadian ensemble) has high probabilities (70-90% chance) for measurable precipitation heading into Sunday so confidence is high that there will be at least some periods of showers and storms this weekend.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 629 PM CDT Mon May 11 2026

An increasing low-level wind field later this evening will both begin to increase sfc winds as well as increase winds at around 2kft to 45-55 kts across the region. As a result, some LLWS will be possible during the overnight hours tonight. Additionally, showers will move through the region during the 06z to 15z timeframe. While cloud bases with these showers will likely be fairly high (around 10kft) which should minimize the vsby and cig category reduction potential, this could allow for more momentum transfer of stronger winds off the deck to the surface. So it while it is certainly possible for gusts of 40-50 kts to occur underneath these showers, confidence is low exactly where more robust showers will be present to bring this risk. Otherwise, cigs will gradually clear later into the morning on Tuesday with winds remaining elevated at 15 to 25 kts with gusts to 35 kts possible. Winds will shift from southerly to northwesterly throughout the afternoon on Tuesday.

ARX WATCHES/WARNINGS/ADVISORIES

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