textproduct: La Crosse

KEY MESSAGES

- Isolated showers possible (15-25% chance) this afternoon and evening.

- Near to slightly below normal temperatures this weekend into early next week with highs in the upper 70s to lower 80s.

- Shower and storm chances (30-60%) return Tuesday into Wednesday.

DISCUSSION

Issued at 1205 PM CDT Sat Aug 1 2026

Rest of Today - Sunday: Isolated Showers this Afternoon and Evening

Cooling temperatures aloft with northerly flow in place will allow for some instability (around 500-750 J/kg of MUCAPE) to be present across the region this afternoon and evening allowing for the development of some isolated showers during this timeframe as hinted at in some of the CAMs. Overall, given the fairly skinny instability profiles and lack of deep-layer shear, would think that robust convective development is very unlikely. In any case, cannot rule out (15-25% chance) some isolated showers late this afternoon and into the evening.

Otherwise, upper-level ridging with accompanying surface high pressure will move into the region overnight and into Sunday resulting in clearing skies and light winds near the surface. Consequently, cannot fully rule out some fog formation in river valleys, however the stronger winds persisting off the surface will likely mitigate this. Temperatures will likely remain seasonable with northeasterly surface flow keeping temperatures slightly cooler than normal with highs generally in the upper 70s to around 80 degrees for Sunday.

Monday - Wednesday: Increasing Rain Chances Tuesday/Wednesday

Fairly dry conditions are expected to begin the work week with the aforementioned upper-level ridging and surface high pressure in place for Monday. Consequently, a relatively persistence forecast is expected for Monday with highs generally in the upper 70s to lower 80s with minimal sky cover. However, the pattern changes as we head into Tuesday as a shortwave trough pushes through the Dakotas by Tuesday morning, switching our flow aloft to more zonal. As this occurs, a weak surface boundary associated with the aforementioned shortwave trough pushes through the area late Tuesday afternoon through Wednesday with the grand ensemble (GEFS/EC/Canadian ensemble) having increased probabilities (50-80%) for measurable precipitation during this period. Overall, not overly impressed with instability and shear profiles in the deterministic GFS during this period as a fairly substantial low-level EML keeps sounding profiles fairly capped. This limited potential for severe weather is highlighted in the joint probabilities for SBCAPE and bulk shear in the grand ensemble (GEFS/EC/Canadian ensemble) having extremely low (under 5%) for having favored shear and instability during this period. Consequently, thinking that while this is our next period for widespread rain across the area, the probability for organized severe weather is very low at this time.

Thursday - Friday: Seasonable, Small Chances for Showers and Storms

As we head into the later half of next week, continued zonal to northwesterly mid-level flow will perpetuate the risk for any showers and storms if any shortwave perturbations can sneak their way into the area. There are some probabilities (20-40%) in the grand ensemble (GEFS/EC/Canadian) for favorable instability (over 1000 J/kg of SBCAPE) and bulk shear (over 30 kts) for severe weather across the area during this period. However, confidence across deterministic and ensemble guidance is fairly low with how these features would be resolved so thinking the small precipitation chances in the NBM (15-25%) are appropriate at this time. Additionally, with continued zonal to northwesterly flow, thinking temperatures will remain relatively seasonable with the NBM keeping the inter-decile range for high temperatures in the middle 70s to upper 80s through Friday.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 605 PM CDT Sat Aug 1 2026

VFR conditions expected at the terminals for the next 24 hours with light north/northeast winds at less than 12 kts. With the recent rainfall and generally light winds overnight, low stratus is likely to develop across much of Southwest Wisconsin overnight but current guidance keeps this out of the KLSE terminal so have continued with this heading. Some patchy fog is also possible across the Upper Mississippi Valley overnight but confidence is a bit too low to include a mention with this package.

ARX WATCHES/WARNINGS/ADVISORIES

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