textproduct: La Crosse

KEY MESSAGES

- Low confidence (20-40%) in storms through Independence Day causing heavy rain slightly increases (30-50%) through the nighttime.

- Low confidence (20-40%) in temperatures and precipitation chances through start of the week.

DISCUSSION

Issued at 120 PM CDT Fri Jul 3 2026

Precipitation Chances Through Saturday Morning:

Little to no confidence in pattern and subsequent precipitation potential through tonight as the moist airmass (PWs 1.75") remains over the Upper Mississippi River Valley with a disheveled multi-level pattern over much of the CONUS. A split in initial storm probabilities north and south of the forecast area early this afternoon due to meager upper level diffluence and weak perturbations is driving storms through northern IL and western MN. While the line through western MN has been initiating storms on the southeastern flank through the early afternoon, it remains well to the west of the local forecast area and the accompanying upper level perturbation likely will experience ageostrophic descent to the east-southeast.

The surface frontal boundary along our southern peripheral counties in northeast Iowa and southwest Wisconsin will be the main concern as recent heavy rain has caused flooding impacts and therefore have higher PoPs in these areas through tonight.

Precipitation & Storms Tonight:

Inter/intra high resolution model disagreement in local storms remains high tonight through Saturday as members display a wide variety of simulated reflectivity solutions without a clear lack of widespread lift while the increased moisture and mid- upper level instability support storm formation. Given surface temperatures struggling to recover through the morning hours and the lack of overall forcing, have decreased PoPs from NBM using a multi-faceted blend of high resolution disagreeing models today and slightly decreased Saturday to better match confidence.

Saturday Night Storm Potential:

Precipitation potential and confidence /slightly/ increases Saturday night as a surface low pressure takes shape near the forecast area towards the Great Lakes. Respondent northwest low level winds may be sufficient to drive storm chances depending on diurnal timing. A later progression and formation of the low would abate higher storm chances to our east through Sunday morning while an earlier timing would align to our west, progressing east through the area while weakening overnight Saturday into Sunday morning.

Through The Start of The Week:

This weak low continues to affect confidence over the Upper Mississippi River Valley through the start of the week, influencing relatively drier and colder east winds bifurcating the forecast area as upper level heights drive return flow around the local forecast area. Therefore, warmer and more moist air infiltrating the surrounding areas will drive higher storm confidence until the synoptic wave breaks southeast through midweek.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 632 PM CDT Fri Jul 3 2026

VFR conditions currently present at the terminals. Showers and storms this evening are expected to stay well to the south across far Southwest Wisconsin. These will move out of the area over the coming hours with generally low chances for precipitation overnight. Another chance for mist and fog will be possible given the low level saturation so have once again gone with MVFR CIGs and visibilities at both terminals for the late overnight period. This should clear out around sunrise with VFR conditions returning at the terminals. Chances for showers and thunderstorms will return for tomorrow afternoon, especially for the LSE terminal with higher PoPs along and east of the river. Winds through the period will be light and variable.

HYDROLOGY

Issued at 120 PM CDT Fri Jul 3 2026

A lack of local precipitation through the early afternoon has allowed rivers to recover some as runoff from recent heavy rains caused flash/river flooding. Highest accumulations were recorded in far southeast Minnesota with 6" to 10" of rainfall. Have continued Flood Watch for southern peripheral counties in northeast Iowa and southwest Wisconsin where the frontal boundary may cause storms through this evening into tonight.

The moist airmass (1.75" PWATs) remains parked over the forecast area through Saturday night, persisting heavy rain concerns where storms form. A lack of widespread, strong atmospheric forcing limits any confidence in storm formation locally until Saturday night when low level winds may provide sufficient lift to cause storms progressing southeast. However, should daytime heating reach convective temperatures, could see some slow moving, heavy rain producers causing flash flooding especially where heavy rain has already fallen.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Flood Watch through Saturday morning for WIZ061. MN...None. IA...Flood Watch through Saturday morning for IAZ029-030.