textproduct: La Crosse

KEY MESSAGES

- Widespread rain moves through the region today, resulting in rainfall totals around 1-3 inches, highest across southeast Minnesota, northeast Iowa, and southwest Wisconsin. Locally higher amounts of 3-5 inches are possible across these areas.

- Rainfall moves east of the region throughout the day Saturday, resulting in dry conditions Saturday night through Monday.

- Showers and storms return to the region late Monday night through Wednesday (30-50%).

DISCUSSION

Issued at 1251 AM CDT Fri Jul 31 2026

Overnight into Tonight

A surface low will track southeast from southwest Minnesota into southeast Iowa today and into northern Illinois tonight. The initial band of rain will be northwest to southeast from southwest Minnesota into southeast Minnesota and northeast Iowa. As low pressure gradually deepens this afternoon and tonight, a deformation band will develop over southern Minnesota and northern Iowa. As this occurs, the band will become more orientated west to east. Where this occurs, the longevity of the rainfall will increase.

Precipitable water values climb into the 1.75 to 2.4 inch range across southeast Minnesota and northeast Iowa, and from 1.2 to 1.75 inches this morning. These values then decrease into the 1.5 to 2 inch range this afternoon and into the 1 to 2 inch range tonight. The highest precipitable water values for this afternoon and evening will be south of Interstate 90.

A mesoscale convective complex currently over western Iowa will continue to move east southeast overnight and this morning. As it does, it will keep most of the instability well south of the forecast area. There might be some 0-1 km mixed-layer CAPES up to 250 J/kg across Fayette and Clayton counties.

The 31.00z HREF has a mean 24-hour rainfall totals of 1 to 3 inches across southeast Minnesota, northeast Iowa, and southwest Wisconsin. The 24-hour localized probability-matched mean has generally a 4 to 10 inch along the Buffalo ridge in Minnesota. There is even a very small area in the 10-15 inch range. This makes sense because you have an overlap of the instability and high precipitable water values (2-2.5 inches) in that area. Further southeast into southeast Minnesota, northeast Iowa, and southwest Wisconsin there is a narrow potential of 3 to 5 inches. The question is where this might occur. With the global models having a tendency of being too far north with their QPF, there is concern that the models might be too far north and this band might be further south closer to the better instability. We have already seen a slight south in the CAMs this evening. Earlier in the evening, they were either along or north of Interstate 90. They are now more south of Interstate 90. Will there be more of southern shift as we progress through the overnight and into Friday morning?

High temperatures today will range from the upper 60s to mid-70s. Low temperatures will be around 60 for tonight.

Saturday

The surface low will slowly move southeast across northern Illinois. There is general consensus in the global models and their ensemble members for a deformation band to orientate itself from northeast to southwest just southeast of the southwest and central Wisconsin. They will likely see some more rain, but it would likely be on the light side (up to a tenth of an inch). High temperatures will range from the mid-70s (southwest and central Wisconsin to around 80 elsewhere.

Saturday Night into Monday

High pressure will keep the area dry from Saturday night into Monday. High temperatures will range from around 80 to the mid-80s. Low temperatures will range from the lower 50s to lower 60s.

Monday Night into Wednesday

A cold front will move into the area on Monday night and then linger across the area into Wednesday. While the 0-1 km mixed- layer CAPES will occasionally climb up to 1000 J/kg at times, both the 0-3 and 0- 6 km shear remains weak. As a result not seeing any organized severe weather at this time. High temperatures will range from the mid-70s to mid-80s. Low temperatures will range from the mid-50s to mid-60s.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 558 AM CDT Fri Jul 31 2026

Showers have made their way into the region this morning. Observations across central Minnesota and northern Iowa suggest MVFR/IFR conditions are present with said showers and are expected to continue through the day as the showers move through the region. There still appears to be some potential for thunderstorms late this morning/this afternoon, primarily south of I-90, where dry-slotting associated with the low pressure center may allow for some clearing/destabilization. That said, thinking TS impacts will likely stay south of the TAF sites so have continued to leave mentions out. Surface winds also increase today in response to a strengthening low level wind field allowing for surface gusts of 15-30KT, strongest west of the Mississippi River.

Rainfall and MVFR/IFR conditions continue into tonight, but begin to improve from west to east towards the end of the TAF period as the rainfall and low pressure continues eastward.

ARX WATCHES/WARNINGS/ADVISORIES

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