textproduct: La Crosse

KEY MESSAGES

- Likely dry (80%) today, persistent precipitation potential from Tuesday through Thursday across the local forecast area, shunted along southern periphery until Saturday.

- Cooler and drier for the latter half of the week for much of the local forecast area.

DISCUSSION

Issued at 1256 AM CDT Mon Aug 10 2026

Low Confidence, Persistent Precipitation Potential After Tuesday:

A relatively nebulous synoptic pattern leaves much to be desired regarding precipitation and storm confidence through the week. Regardless, a well saturated airmass south of a quasi-stationary boundary near or over the southern half of the local forecast area from northeast Iowa into southwest Wisconsin eventually expected to be shunted along our southern periphery through the latter half of the week. However, initial near term model consensus increases precipitation potential due to increasing low level moisture Tuesday morning and again Tuesday night.

While overall confidence is low, the warm, moist airmass has the potential for enhanced instability (2000+ J/kg, LREF) due to the warm frontal boundary potentially providing sufficient lift towards higher deep layer shear. Most likely storm mode would quasi-linear or broken cellular storms as storms lift east-northeast along the frontal boundary. Medium-range Real-time AI NWP Convective Hazard Forecast models (Pangu, FengWu) paint 5% to 15% probabilities Tuesday 12Z to Thursday 12Z as a result.

Confidence decreases further through midweek as high pressure attempts to drive a back-door cold front across the local forecast area, forcing highest confidence along our southern periphery in northeast Iowa. Given a sharp cutoff in precipitation and storms expected, should this frontal boundary push/sag north/south, local PoPs will require additional adjustment.

Cooler Through End Of Week, Weekend Storm Chances:

Canadian high pressure sagging southeast through the end of the week ushers in a cooler, drier airmass before a passing low advecting precipitation and storm chances through the weekend returns and persists Upper Mississippi River Valley storm/precipitation chances.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 550 AM CDT Mon Aug 10 2026

Fog and low stratus has overspread much of the Upper Mississippi Valley this morning with widespread MVFR to LIFR conditions present across the region. These conditions will continue for the next few hours, gradually dissipating after sunrise. VFR conditions will prevail after that with light winds out of a general easterly direction. An area of rain of showers and storms is expected to move into the area late in the period. There was high enough confidence to include a prevailing group for KRST but not at KLSE just yet as the bulk of the precipitation arrives after the end of the 12Z cutoff. Have included a PROB30 at KLSE for now to cover this activity.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Dense Fog Advisory until 10 AM CDT this morning for WIZ017-029. MN...None. IA...None.