textproduct: La Crosse

KEY MESSAGES

- Nice, slightly warmer than normal weekend ahead.

- Severe thunderstorms may return Monday. If these occur, all hazards would be in play. However, many uncertainties remain and severe storms remain more probable to our south in eastern IA.

- Colder through next week with slightly below normal temperatures potentially nearing freezing overnight for some by midweek.

DISCUSSION

Issued at 1046 PM CDT Fri Apr 24 2026

Nice weekend

Drier conditions in the wake of Friday morning's front should lead to a nice weekend. Light winds and clear skies tonight may lead to locations around Black River Falls dropping into the mid 30s briefly. Temperatures will be on a slow uptick as southwesterly flow aloft comes to dominate the central CONUS and winds at the surface become southeasterly while heights aloft build. While precipitation is highly unlikely (90% chance to stay dry) a couple disturbances in the southwesterly flow rolling downstream just to our northwest could bring a bit of rain during the day Saturday, mainly to areas north of an Austin MN to Osseo WI line.

Severe storm potential Monday

Northern and southern stream upper jets look to phase leading to large amounts of upper divergence over the central CONUS Monday. Initial lee surface low centered somewhere near western KS looks to rapidly shift to somewhere in MN/IA/MO where right entrance region of a jet over Canada and left exit region of a jet over KS/OK overlap. Substantial southerly moist advection will occur east of this low with 24.12z NAEFS/ECENS southerly 850mb flow above the 99.5th percentile. Given similar data sets have 200/500mb southwesterly winds above the 90th percentile, strong wind shear looks to develop with a 55-85% chance to exceed 40 kts of deep shear per 24.12z LREF. Progged hodographs are long with plenty of turning in the low levels so thinking supercell structures and all hazards would be in play if sufficient instability is present.

All the above said, there remain two important uncertainties - how far north appreciable moisture and instability reach and if WAA lead to recurrent precip through the day, preventing destabilization. On the first point, ensemble guidance seems to point toward mainly our southern forecast area - northeast Iowa and southwest Wisconsin - being in play, particularly with the 24.12z GEFS, where joint probabilities of sufficient CAPE, shear, and low CIN are 40-50% while the 24.12z CMCE probability is lower, around 20-30%, again focused on this area. 24.12z ECENS progged surface lows are clustered farther north, having probabilities to around the I-90 corridor, albeit using MUCAPE rather than surface parcels. Needless to say, while the chance for severe storms is higher to the south of our forecast area, those across the region will need to keep an eye on Monday.

Turning cooler after Monday

Longwave upper trough slowly churns eastward Tuesday into next Friday with this feature over Hudson Bay south to the Great Lakes Friday morning. Turn toward lower heights aloft should lead to highs in the 50s and 60s per 25.01z NBM interquartile ranges. Of concern for impacts, morning lows may drop to or below 36 (frost) or below 32. Wednesday (20-60%), Thursday (30-70%), and Friday (40-80%) have a shot at seeing frost conditions and a smaller chance (5-20%) to drop below freezing.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 510 AM CDT Sat Apr 25 2026

VFR conditions are expected throughout the TAF period with high and mid-level clouds expected. Winds will increase this afternoon and evening to around 5-10 kts being predominantly from the east. Winds will then shift to southeast overnight.

ARX WATCHES/WARNINGS/ADVISORIES

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