textproduct: La Crosse

KEY MESSAGES

- Slightly below normal temperatures through the end of the week with daytime highs in the 60s an overnight lows from the 40s to low 50s.

- Remaining mostly dry through the week with highest precipitation chances (40-80%) decreasing as they shift east Saturday night through Sunday.

DISCUSSION

Issued at 1229 AM CDT Wed Sep 23 2026

Cooler & Mostly Dry Through Friday:

An area of cyclonic upper level flow and an accompanying shortwave trough is seen progressing east through the southern Great Lakes on GOES water vapor imagery loops, elongated between two synoptic areas of anticyclonic upper level flow. East low level winds associated with the anticyclonic flow over Canada will cause a persistently cool and mostly dry forecast into the weekend. Sufficient forcing to remove the back door cold front's influence may not reach the local forecast area until mid next week.

Sprinkles will be possible late this afternoon and early evening from enhancement of accompanying low level cold air advection primarily east of the Mississippi River Valley locally in southwest Wisconsin.

Weakening Precipitation Chances Approaching Forecast Area Thurs & This Weekend:

As the upper level cyclonic flow exits through the end of the week, unification of the upper level heights causes temporary amplification of the upper level ridge over the forecast area. Resultant degradation of incoming mid-upper level waves and accompanying positive vorticity advection reduces precipitation chances from west to east as they approach the local forecast area. Initial, low (10-15%), probabilities Thursday morning graze western peripheral counties in southeast Minnesota increase Friday night into Saturday (50-90%) only to quickly decrease whilst advecting east through the local forecast area (30-60%) on Saturday.

Low Confidence Longer Term Forecast:

Long term global models differ on location of a Nor'easter and synoptic upper level troughing sufficient to overcome and cause anticyclolysis over the Great Lakes, responsible for the persistent low level east winds, through the start of the new week. Expect further details in timing and exact location of synoptic ingredients to increase in confidence as forecast hour nears, increasing local confidence in precipitation chances through early next week.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1229 AM CDT Wed Sep 23 2026

Low potential (10-20%) for patchy mist/fog exists across portions of northeast Iowa and southeast Minnesota overnight, but the greatest visibility impacts should largely remain to our west. Slightly increased low level winds are expected to hinder any valley fog impacts at KLSE although some valley fog/low level stratus may make an appearance in the Wisconsin River Valley as we head towards daybreak. Outside of limited mist/fog, VFR conditions are expected over the next 24 hours with light east winds prevailing and diurnal cumulus around 3-4kft developing this afternoon.

ARX WATCHES/WARNINGS/ADVISORIES

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