textproduct: La Crosse

KEY MESSAGES

- Showers and storms currently over western Minnesota and Iowa move into our area this afternoon and overnight. Some storms could be strong to severe. Rainfall amounts of 0.5 to 1 inch are expected, locally up to 2 inches.

- Temperatures cool to near normal Friday through early next week. Highs in the 60s and lows in the 40s are expected.

- Another round of showers and storms looks likely (70-90%) Sunday night through Monday.

DISCUSSION

Issued at 115 PM CDT Thu Apr 23 2026

Tonight - Friday Morning: Showers and Storms

Showers and storms currently over western Minnesota and Iowa shift eastward through the region this evening and overnight along a cold front. Ahead of the front, isolated storms are possible across our area through the afternoon hours along a ribbon of 850hPa moisture transport. There's some uncertainty whether these storms can develop at all as HRRR/RAP soundings depict warm air in the mid-levels resulting in capping inversion. However, the moisture transport is able to saturate this layer, thunderstorm development is favored. Storms that develop would pose a threat for hail up to 1 inch owing to steep mid-level lapse rates of 7-8C/km and SBCAPE of 1500-2000 J/kg per the 23.13z RAP although storms in this environment will be short lived as 0-6km bulk shear is weak at best, so very little residence time will occur for hail to grow bigger than this.

As the front moves through the region, the ongoing convection is expected to maintain itself owing to forcing from the front as well as MUCAPE of 1000-1500 J/kg. The linear to quasi-linear mode will continue as 0-6km shear remains weak, mostly locked up in the lower levels. Because of this, damaging winds are the primary threat along this line, although if any bowing segments develop and are able to orient perpendicular to the 0-3km shear vector, they run the risk of a weak tornado developing given curvature in the 0-1km layer per model hodographs.

Apart from the strong/severe storm threat, heavy rainfall is expected across the region as the storms move through the region. PWATS of 1.2-1.3 inches continue to be depicted in high- resolution guidance, well above the 90th percentile of climatology. Decent probabilities for rainfall amounts over 1 inch remain in the 23.12z HREF, sitting around 30-60% with some signal for up to 2 inches. Overall expectations are for amounts generally 0.5-1 inches with localized areas up to 2 inches, most favorable over northeast Iowa and north-central Wisconsin per the 23.12z HREF 24hr LPMM. Widespread flooding is not a concern at this point, but ponding is expected in low-lying areas and rises on rivers in smaller basins where the heaviest rainfall occurs.

Overall, all severe hazards are on the table this afternoon and evening through two rounds of storms, although significant severe potential is not expected given the messy storm mode. Severe potential is highest west of the Mississippi River with the initial onset and wanes with eastward extent overnight as instability decreases. The front and showers/storms move east of our area around 3am Friday.

Friday - Sunday: Cooler Temperatures and Dry

Cold air advection behind the front brings temperatures closer to normal for this time of year, with highs in the 60s and lows in the 40s. Lows may be able to fall into the 30s north of I-94 Friday night into Saturday morning given clear skies and drier air shifting southeastward with the 23.13z NBM suggesting an 20- 40% chance to fall below 37F. Given vegetation is beginning to green up across the region, some concern for plant damage from frost exists during this timeframe.

A weak shortwave at 500hPa moves across the eastern Dakotas/western Minnesota early Saturday morning with the CAMs beginning to suggest some precipitation may be observed with the feature. While the shortwave is currently shown to stay west of our area, if it shifts further east, some light precipitation may occur for those west of the Mississippi River, although dry air in the subcloud layer would act to hinder precipitation from reaching the surface. Outside of this outlier precipitation potential Saturday, the coming weekend will largely be characterized by dry weather.

Sunday Night - Monday: Additional Showers and Storms

The next event for showers and storms comes Sunday night into Monday as a 500hPa trough ejects into the central Great Plains, developing a surface low that lifts northward into the Upper Midwest on Monday. Confidence in rainfall is high at this point with the bulk of deterministic and ensemble guidance in agreement with this low moving northward into our area. The 23.00z LREF paints 70-90% probabilities for measurable rainfall in our area Monday and even has a signal for 1 inch or greater at 10-20%. The 23.13z NBM depicts a similar scenario with 70-90% probabilities for measurable precipitation and 30-50% for 1 inch or greater.

The main uncertainly regarding the system is the track of the parent shortwave and surface, which have shifted considerably northward in the last 24 hours. This brings the low more directly overhead the Upper Mississippi River Valley, resulting in the warm sector of the cyclone into our area. As such, instability has increased across our area with MUCAPE now on the order of 1000-1500 J/kg depicted in the deterministic guidance. The new track also brings the attendant 500hPa jet streak overtop of the region as well, acting to increase 0-6km bulk shear, which sits at 30-40kts assuming a surface based parcel, although little shear exists in the 3-6km layer which would lead to difficulty sustaining updrafts, similar to today. This current set-up is favorable for strong to potentially severe storms Monday, although perhaps not ideal. The SPC highlights portions of northeast Iowa and southwest Wisconsin in a 15% probability for severe weather on Day 5 which is also shown in AINWP convective guidance. All this said, while details will be ironed out over the weekend, this will be a period to watch as the new week approaches.

AVIATION /00Z TAFS THROUGH 00Z SATURDAY/

Issued at 633 PM CDT Thu Apr 23 2026

Two lines of thunderstorms are moving through the region this evening. The first is moving from SW to NE through much of Wisconsin as another is moving in from the west across southern Minnesota. The first will be out of the local area as the second line moves through from west to east over the next 6 to 8 hours. IFR vsbys are possible in heavy rain as these storms move through, with brief MVFR ceilings. A dry airmass moves in behind the front, leaving VFR conditions to return after the storms through Friday.

ARX WATCHES/WARNINGS/ADVISORIES

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