textproduct: La Crosse

KEY MESSAGES

- Wintry impacts are expected Wednesday night and Thursday, especially near and north of I-94. Confidence is increasing there, with snow and sleet (1-3 inches), and ice up to one- quarter inch in the forecast. Further south some minor icing accumulations could occur to I-90, but warmer temperatures have pushed ice accumulations north. Rainfall of 1-2" is expected with river rises. Some severe storms may be possible Thursday afternoon as the area warms.

- Late week, another system is moving through the area bringing additional rainfall and more wintry weather possibly. Some wintry precipitation could occur in the northern areas. Rivers will be on the rise and this system could cause further rises, increasing flooding threats.

DISCUSSION

Issued at 150 PM CDT Tue Mar 31 2026

Midweek System Brings Most Impacts North of I-94

A complex storm moves into the area later Wednesday afternoon lasting into Thursday. This brings wintry weather on the front end, transitioning to rain, and severe thunderstorm potential by Thursday afternoon for some. Since yesterday, the storm has trended further northwest with the track, placing the area in a warmer temperature regime. The ECMWF ensembles for the past few runs have become more clustered in a low track near or west of La Crosse and more tightly clustered than the GEFS. The 31.06Z GEFS low pressure centers track (mostly) near or east of La Crosse which is a colder solution. The probabilities for icing have likewise shifted north of the I-90 corridor, with rain falling under warmer temperatures.

The forecast problem for icing is really about surface temperatures as the warm layer aloft is rather large with a MaxT of 5-10C. Wet- bulb temperature becomes a key ingredient to ice accumulation and with the surface ridge building in overnight and easterly flow Wednesday, north-central WI has the lowest dewpoints and wetbulb temperatures (in the 20s) at freezing rain onset. Thus, the main threat area for icing is still more apparent and of higher confidence northeast of I-94. The 31.00Z GEFS and GEPS probabilities for 1/4 inch plus of ice are in the 40-50% range there, increasing eastward. These are also about a county north since yesterday. The ECMWF ens has a substantial period of freezing rain dominant in the membership as well Wed night through about noon Thu. That area will see some front end snow/sleet (1-2" in the latest forecast) before transitioning to freezing rain after Thu 12 am. During that period, model mean liquid equivalent precipitation is around 1 inch. Thus, a Winter Storm Watch for Clark and Taylor counties has been issued for the potential of 0.25" of ice. Sometimes in April, ground warmth can cause greater damage to trees - limbs away from that warm source.

Further south of Clark and Taylor counties, roughly to about the I- 90 corridor, temperatures near the surface are forecast to be right near or above freezing. River valleys should have little to no ice accumulation with above freezing temperatures. But, some light ice accumulation could occur Wednesday night prior to the warming especially heading north away from I-90 and on higher terrain (where it is colder). By noon Thursday, even areas north of I-94 convert to rain. This will lessen the overall impacts of prolonged ice...any icing from Wed night and Thu morning should melt Thursday.

Overall, the Grand Ensemble has shifted the max precip band northwest from central and southwest WI to now through the center of the local area: Waterloo IA to Wausau WI, with 30-40% probabilities of over 1.50" totals in the max band. This incoming air mass is impressive with near climatology maxes for the precipitable water inflow. Strong forcing signals are seen in this negatively tiled system with moderately strong 850 mb moisture transport convergence surges Wed night and Thursday. Many of the river basins should be able to tolerate 2" of rain. See the Hydrology section for more.

The warm sector surge into northeast IA through central WI and south Thursday afternoon seems to indicate, per model soundings, the potential for possibly severe thunderstorms southwest though east of La Crosse. ML CAPE is on the order of 500-1000 J/Kg in the warm sector in a small region feeding into the low center approximately near La Crosse 4 pm Thursday. These storms could be surface-based and would have ample wind shear. However, the low-level curvature is in question as it seems once parcels become surface-based, some surface wind backing occurs creating more of a straight-line hodograph. Will have to continue to monitor this tricky lower CAPE, higher wind shear situation for possible discrete, rotating storms in the warm sector.

There is still some uncertainty seen in the ensembles on the track, but overall we feel this is stabilizing a bit.

Weekend Storm Could Bring More Impacts

Closed upper level low tracks across the Northern Plains and Great Lakes Region mainly Friday evening into the weekend. Much of the area will see rain...with a few storms Friday evening. With cooler temps over the area Friday night...the northern parts of the forecast area could see a wintry mix. Some snow could also mix in for the rest of the area on Saturday as colder air filters in on the backside of the upper level closed low. Total precipitation amounts at this time look to be up to an inch in a few locations with this system. Another possibility (20-30 percent) of rain or snow is expected early next week as a weak shortwave embedded in the northwesterly flow aloft moves over the Great Lakes region. Temperatures will be near or slightly below normal through the forecast period.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 627 PM CDT Tue Mar 31 2026

Mainly high clouds are expected through Wednesday morning and then the clouds will lower as a low pressure system approaches the region from the Central Plains. In addition to the clouds lowering, a wintry mix will move into the region during the afternoon.

HYDROLOGY

Issued at 150 PM CDT Tue Mar 31 2026

Probabilities indicate much of the area will see 1-2 inches of rain with the Wed night and Thu system. Many of the river basins should be able to tolerate 2" of rain with within bank rises per the River Forecast Center river ensemble output. However, should more than 2 inches of rainfall (15-25% chance), minor flood stage could be reached on multiple river systems including the Kickapoo, Trempealeau, and Yellow. 3 inch rain totals would bring flooding to the Turkey river...but these 3 inch probabilities are near 0%.

The second storm on Friday night and Saturday could bring more flooding however with rising river levels after the first storm. We dont have details but that far yet, but will be able to get a better handle on the flooding potential for the weekend on Thursday.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Winter Storm Watch from late Wednesday night through Thursday morning for WIZ017-029. MN...None. IA...None.