Mt. Lacrosse Snow Report

538 FXUS63 KARX 240538 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 1238 AM CDT Thu Sep 24 2026 .KEY MESSAGES... - The potential for rain later this afternoon and tonight has increased rapidly from previous forecasts--now up to a 40-70% chance--though rainfall amounts look to be light with only a 10-20% chance of >0.25" west of the Mississippi River. - The potential for rain lingers into Friday and Saturday west of the Mississippi River (20-50% chance). Amounts look light as well and the showers more scattered in nature. - The end of the weekend and start of next week is shaping up to be dry before another stretch of wetter weather pushes through Tuesday into midweek. - Little change in temperatures into next week with readings running slightly below seasonal norms. && .DISCUSSION... Issued at 1200 AM CDT Thu Sep 24 2026 This Afternoon - Tonight: Rapidly Increasing Rainfall Potential The one big change to the near-term forecast has been a rapid increase in the probabilities for light to moderate rainfall spreading eastward from central MN after noon, reaching the Mississippi River towards sunset and lingering for many locales through the night into Friday. A small eastward wobble of the lower tropospheric ridge axis is all it took for the eastward extent of the rain shield to shift from the I-35 corridor to now western and central WI. The signal in the short and medium range ensembles (LREF/EPS/GEFS/HREF) is nearly unanimous in there being rain west of the Mississippi River, with the number of dry members increasing as one heads further east. While the rainfall probabilities are quite high, the intrusion of dry air from 850-700-mb will limit rainfall amounts with the probabilities for >0.25" west of the Mississippi River only 10-20% and less than 10% elsewhere. Friday - Saturday Weak 290K isentropic ascent and broad lower tropospheric confluence look to keep the risk for showers going west of the Mississippi River through Friday--again with minimal rainfall amounts. How the rain on Saturday unfolds is of somewhat lesser confidence with there likely being a sharp cutoff in the eastward extent of the rain between I-35 and the Mississippi River--exactly where is to be determined. Once again, in the absence of deep moisture or lift, rainfall amounts should be minimal with a 20-50% chance of >0.25" and 10-20% chance of >0.50" west of the Mississippi River. Upper tropospheric ridging builds to the west for Sunday and Monday, bringing a reprieve from the light rain to start the new week. Tuesday - Wednesday: Next Widespread Rain Risk A longwave trough will move east through the Mid- and Upper Mississippi River Valley. This will bring rain into the region. There are some models that bring tropical moisture northward into the region. Meanwhile, other models show that this plume of tropical moisture will be southeast of the area. High temperatures will be in the mid- to upper 60s. Low temperatures will range from the mid-40s to mid-50s. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1236 AM CDT Thu Sep 24 2026 Patchy mist/fog is anticipated across central into north- central Wisconsin where skies are favored to remain on the clearer side as we head into the early morning hours, bringing periods of MVFR/IFR visibilities through 13z-14z. Confidence has decreased in mist/fog impacts at KLSE given the increasing cloud coverage and shallow light wind layer, but will remain something to monitor overnight. Beyond this morning, showers move in from the west through the afternoon and evening, primarily impacting those west of the Mississippi River (50-60%). However, any precipitation is expected to be light with VFR ceilings and visibilities prevailing. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Boyne/Skow AVIATION...Falkinham