textproduct: La Crosse

KEY MESSAGES

- Storm chances increase Tuesday night from west to east. Local severe threat remains low (<5%) given evening to nighttime forecast expectation.

- Near normal temperatures expected through end of the week with precipitation chances increasing this weekend.

DISCUSSION

Issued at 1235 AM CDT Tue Aug 25 2026

Increasing Precipitation Chances Tuesday:

Low level return flow through the Upper Missouri River Valley Monday night is advecting increased moisture upstream of the local forecast area through Minnesota with PWATs (RAOB/GOES- derived) above 1.5" through the Dakotas into western Minnesota. Upper level water vapor imagery loops show a stout upper level trough topping broad ridging across the western CONUS phasing east overnight into Tuesday morning, ushering in local precipitation and storm chances through much of Tuesday.

Storm Potential Tuesday:

Local severe storm threat remains low (<10%) due to main instability axis of 1000+ J/kg MLCAPE traversing the local forecast area from the evening into the nighttime hours. While accompanying shear values remain high in the lowest levels (0-1km: 25kts, 0-3km: 20- 35kts), lack of coincidental timing with peak diurnal heating lacks overall confidence for accessing the strongest, near surface values. Therefore, a marginal risk for the Storm Prediction Center persists for much of the forecast area.

Weekend Precipitation Chances:

The synoptic trough advects low level cold air advection through the Upper Mississippi River Valley Wednesday, keeping apparent temperatures mostly in the 70s to low 80s for much of the local forecast area. Subsequent precipitation chances increase through the weekend.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 552 AM CDT Tue Aug 25 2026

VFR conditions should prevail over much of the period. IFR/LIFR fog, ongoing once again in the Wisconsin River valley, may return after 06z Wednesday but, with winds across the area becoming northwesterly at that time, am doubtful it spreads to river valleys elsewhere. Other thing to watch is potential (20-50%) for TS east of the Mississippi from 22z to 08z. At this time, think this should (80% chance for no TS) remain east of LSE, so have kept the TAF free of even a PROB30 with this update.

ARX WATCHES/WARNINGS/ADVISORIES

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