textproduct: La Crosse

KEY MESSAGES

- Severe storm risk this afternoon remains a lower confidence forecast owing to early morning storms. Pockets of damaging winds and heavy rain would be the main threats, which look to be focusing over south-central MN and north-central IA.

- Additional rounds of storms return to the forecast from early Sunday morning through midweek. There may exist a severe weather threat with these storms, but confidence in such details is low at this time.

- Seasonal temperatures continue for the weekend with a slight cooling trend by midweek as the storm risk pushes south.

DISCUSSION

Issued at 110 PM CDT Fri Aug 7 2026

This Afternoon: Storm Details

Several rounds of storms have developed since sunrise on the nose of a 850-700-mb theta-e ridge that is advancing eastward just ahead of a surface cold front bifurcating Minnesota from SW to NE. As expected, the complex hodographs and linear forcing, coupled with a narrow instability axis in which storms have little residence time, have resulted in transient storm structures and a rapid upscale growth. The southern side of the line has become the dominant feature as of 18Z and is making the southeastward turn as the cold pool becomes established. This trend will continue over the next few hours, with damaging winds being the main threat.

Additional storms may form along the nose the the theta-e ridge, but time is running out for this to occur before the cold front arrives. The cold front may serve as a source for additional convective initiation, but there has been ample anvil shading along the front and any risk for these storms may be displaced further north towards northern Wisconsin.

Sunday Morning: Next Round of Storms, Heavy Rain Threat?

Cooler and more stable air filters southward tonight in the wake of the cold front and persists for much of Saturday as the front stalls and pivots near I-80 in Iowa. Lee cyclogenesis along the Front Range helps push this (now warm) front northward across the region once again late Saturday night into Sunday morning. Aided by a 30-40 kt LLJ, these storms could be more robust in nature and produce heavy rainfall. While confidence is increasing that there will be some sort of MCS across the region, the devil is in the details as to when exactly it will form, which will dictate its track. Aided by increasing Gulf moisture and PWATs of 1.5 to 2 inches, coupled with an increasing line parallel storm motion, this complex could put down efficient rainfall rates in short order and will need to be monitored for any flooding risk.

Early Next Week: Continued Storm Risk

The lower tropospheric front stalls between central Iowa and southern Minnesota for later Sunday through Tuesday, presenting multiple windows of opportunities for convection that could bring heavy rain. However, details of these storms remain very nebulous and will be refined over the coming days.

Mid to Late Week: Drier and Cooler

The medium to longer range solutions are in general agreement that a a polar airmass will build southward through mid to late week as the surface baroclinic zone sags southward. This should result in cooler and drier weather, though with the surface front not far away, it will not take much of a wobble in the forecast to bring this rain back northward.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1200 PM CDT Fri Aug 7 2026

Primary concern over the next 24 hours is the likelihood (60%) for TS to move west to east across the area this afternoon and evening, affecting both LSE/RST. Have maintained previous TAF posture of TS mentions with TEMPO groups of IFR visibility but with timing adjustments. After TS departs to the east, northwesterly winds should be predominant and should (80%) serve to keep stratus/fog concerns confined to the Wisconsin River valley around OVS overnight into Saturday morning.

ARX WATCHES/WARNINGS/ADVISORIES

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