textproduct: La Crosse

KEY MESSAGES

- Rain exits throughout the overnight hours and into Saturday morning. Highest additional rainfall amounts will be near and south of I-90 where 1 to 2 inches of rain are likely (50-90% chance). - Drier conditions expected for the weekend with highs in the upper 70s to lower 80s.

- Shower and storm chances (20-40%) return Tuesday into Wednesday.

DISCUSSION

Issued at 129 PM CDT Fri Jul 31 2026

Rest of Today - Tonight: Rain Continues this Afternoon and Evening, Exits to the East Overnight

Rain will continue to pivot through the region throughout the afternoon and into the evening hours. Early this afternoon the surface cyclone responsible for our precipitation is currently centered over portions of southwest MN and northwest IA with the dry slot associated with it pushing into portions of northeast IA and southeast MN. As we continue through the afternoon, this system is expected to move generally to the southeast through Iowa which will then allow for the deformation band associated with this surface low to move overhead. Within this regime, sloping frontogenesis as a result of a TROWAL region will pivot over the region and reinvigorate shower development through the remainder of the afternoon and evening, particularly near and south of I-90. The main question that remains is if any instability can push northward into the local area as this stronger forcing regime moves overhead. There is some indication in the recent RAP that we could build in 100-250 J/kg of MUCAPE in portions of southwest WI and northeast IA later this afternoon and into the evening. Consequently, have noted that some of the CAMs are a bit more aggressive with developing robust convection in these respective areas.

Overall, expected additional rainfall amounts will be greatest near and south of I-90 where this aforementioned forcing regime is present this afternoon and evening. Consequently, the 31.12z HREF has an inter-quartile range of anywhere from 1 to 2 inches of rainfall where this forcing is present. The 90th percentile members of the HREF suggest some pockets of 3-4+" may be possible, most likely with any areas that see convection repeat over the same locations. However, seeing this higher amounts are yet again contingent on if we can manage to get any instability northward into the region to promote convection. In these localized cases, cannot rule out some isolated flooding, however this would be relatively sparse in nature. Eventually, as we head into the overnight and daybreak on Saturday, the broader surface low and associated upper-level trough will continue to push east of the local area, which in turn will note a west to east progression of the broader precipitation shield, likely exiting much of the local area by late morning.

This Weekend: Drier & Slightly Cooler Than Normal

As the aforementioned surface low pressure center pushes east of the area, upper-level ridging will build in behind it for the weekend with attending surface high pressure pushing into the region later Saturday and into Sunday. Consequently, expecting skies to clear throughout the day on Saturday with no chances for precipitation after the morning hours. Additionally, with flow switching to northerly over the weekend, expecting temperatures to remain slightly cooler than normal with the inter-quartile range in the NBM keeping high temperatures across the area in the middle 70s to lower 80s.

Early Next Week: Precipitation Chances Return Tuesday & Wednesday

By the time the beginning of the upcoming work week rolls around, the previously mentioned upper-level ridging and attending surface high pressure remains in place for Monday. However, low-level flow eventually switches to southerly which will allow for a warmer airmass to push into the region. Consequently, temperatures will likely nudge upwards a few degrees on Monday with highs in the lower to middle 80s for most. Going into Tuesday, a pronounced upper-level trough pushes through the Dakotas with an associated boundary pushing southeast towards the local area. Consequently, the grand ensemble (GEFS/EC/Canadian ensemble) has increased probabilities (30-70%) for measurable rainfall Tuesday evening through Wednesday morning as it progresses through the region. Overall, probabilities for severe weather with this wave appear relatively low as the grand ensemble (GEFS/EC/Canadian ensemble) only has around 5-10% chance for ample instability and bulk shear to be present over the region for severe weather.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 630 PM CDT Fri Jul 31 2026

Rain continues to overspread the Upper Mississippi Valley this evening as a surface low pressure system pivots to the southeast over NE Iowa. IFR/MVFR CIGs and visibilities will continue at the terminals through the evening hours with rain gradually ending from northwest to southeast through the overnight hours. Both CIGs and visibilities should improve at the terminals beyond 12Z as some low clouds and mist/fog may linger even as the bulk of the rain has moved out late overnight. VFR conditions will prevail for tomorrow with skies clearing by the afternoon. Gusty east/northeasterly winds will pivot to a more northerly direction as the low pressure system slides southeast tonight with gusts tapering off around midnight.

ARX WATCHES/WARNINGS/ADVISORIES

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