textproduct: La Crosse

KEY MESSAGES

- Heavy rain and storms progress northeast through northeast Iowa, southwest Wisconsin, and central Wisconsin through the daytime hours. Highest rainfall amounts expected along southern peripheral counties where 1"+ of rainfall is possible.

- Low confidence in limited precipitation chances through start of new week, eventually increasing Tuesday, lasting through Wednesday.

DISCUSSION

Issued at 209 PM CDT Fri Jul 11 2025

Tonight: Strong Storms and Heavy Rain Possible

Elevated convection behind a warm front/baroclinic boundary is starting to pop up across portions of northeastern Iowa early this afternoon. Many of these storms are meager at best with better instability residing much further south into central and southern Iowa where SBCAPE is greater than 1500 J/kg. A surface low is currently located across far southeastern Nebraska with a convectively reinforced upper level shortwave present across Iowa in 18Z 500 mb analysis. As we are north of the warm front and quasi baroclinic boundary, the severe threat overall looks pretty marginal but there is a minor threat for large hail with these initial storms, becoming more of a damaging wind threat later on (especially across far southwestern Wisconsin with DCAPEs greater than 500 J/kg) as they will likely grow upscale into more of a MCS/QLCS type feature with time. Vertical shear overall is marginal at 20-30 kts with some pockets of 35 kts across our far southern counties, being aided/enhanced by the shortwave trough. The severe threat will continue through the afternoon and into the evening, likely waining after 00Z.

While the severe threat isn't looking overly impressive for our area, the threat for heavy rain looks much better. Areal pWats sit at 1.5-1.8 inches and warm cloud depths are approaching 3 kft. Any storms will likely be efficient rainfall producers so if we see any training activity, this could lead to signficiant ponding or localized flooding. 11.12Z HREF mean precip totals look to be in the .5 to 1.25 inch range for Northeastern Iowa and Southwestern Wisconsin with lower totals to the north. Due to the convective nature of the storms, there remains some pretty significant differences in the 75th-25th percentiles with the 75th around 1.5-2 inches and the 25th percentile less than .25 inches. Unless we start to see some excessive training, the mean HREF totals look reasonable. Recent (last 24 hours) rainfall across Grant/Clayton counties were generally less than 1.25 inches with the heaviest rains staying south of our area more towards Dubuque, Delaware, and Buchanan counties. Soils and rivers across the area should be able to handle the rain, keeping widespread flooding concerns at bay for the time being. A "cold front" associated with a surface low across Western Ontario will push unto our area later tonight which could bring some additional low end rain chances through the overnight hours before exiting our area through the day Saturday. Rain chances should generally be over by 12Z for areas west of the Mississippi with low chances (20-30%) lingering into the afternoon before moving off to the east.

Sunday - Monday: Likely Dry, Warming Temperatures

A weak surface high is expected to build into the Mid-Mississippi River Valley behind the cold front, likely keeping conditions dry for Sunday into Monday. We'll see more abundant sunshine across the area, which will allow for temperatures to start climbing back into the mid to upper 80s by Monday with a few places maybe even reaching the 90 degree threshold. With a broad upper level ridge building across the southern CONUS, our area will be in northwest to weakly zonal flow through the start of next week. A stray shower cannot be ruled out Sunday night, especially across north-central Wisconsin, but the general trend should remain dry.

Tuesday and Beyond: Wet Mid-week with Cooler Temperatures

WPC cluster analysis and mid range models are hinting at a weak trough axis developing across the Northern Rockies and subsequently moving east into our area Tuesday into Wednesday. These features are not well resolved in the mid/long range models but moisture will be reinforced by then with south to southwesterly surface flow helping to deepen areal moisture. As the cold front moves through, PoPs increase to likely (50-70%), especially during the day on Wednesday. How the upper level pattern evolves beyond mid-next week is still uncertain but will leave the slight chance PoPs of the NBM for the late week timeframe. Temperatures will be much more pleasant behind the cold front Wednesday into the weekend with highs in the 70s to low 80s.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 1255 AM CDT Sat Jul 12 2025

Scattered showers continue to be possible overnight. During the early afternoon, rain chances (20 to 30%) remain for central Wisconsin. Some patchy fog with visibilities and CIGS dropping into the MVFR/IFR range during the overnight. If enough low- level saturation takes place, in conjunction with the light surface winds, the fog may become more dense and result in LIFR visibilities and CIGS. Any fog and low-level clouds are expected to diminish or leave the area by mid-morning. With northwest flow aloft, some hazy skies will be possible Saturday evening as smoke from Canadian wildfires pushes down into the region.

ARX WATCHES/WARNINGS/ADVISORIES

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