textproduct: La Crosse

KEY MESSAGES

- Strong to severe storms possible today, primarily for the southeastern half of the forecast area with large hail, damaging winds, a few tornadoes as the primary threats. Heavy rainfall leading to flash flooding remains a secondary threat with overall fast storm motions expected.

- Storm chances continue through Tuesday night and Wednesday, eventually ceasing temporarily through Thursday. Additional strong to severe storm chances return Friday afternoon/evening/night.

DISCUSSION

Issued at 1254 PM CDT Tue Apr 14 2026

Severe Storms Today

If you didn't get a slice of the action yesterday, have no fear because we're in for another round of potentially higher end severe weather again today. The main locations under the gun today will be Northeastern Iowa into SW/Central Wisconsin. An outflow boundary from last night/this mornings convection is expected to lift north as an effective warm front. Current guidance is in good consensus that this will stall out across NE Iowa into Central Wisconsin by mid-afternoon. Satellite imagery is already showing this boundary clearly across Central Iowa where skies have cleared early this afternoon. Convective inhibition will erode through the coming hours with daytime heating and ascent ahead of a shortwave upper trough ejecting into the Upper Midwest will support initiation by mid-afternoon. The airmass will be plenty unstable with 2000-3000 J/kg of MLCAPE present on area soundings once the cap finally erodes. Supercells are expected to go up quickly with steep mid level lapse rates and abundant effective bulk shear across the region (30-50+ kts). All hazards will be in play with these storms but the main threats look to be large to very large hail and a few tornadoes (potentially strong). The parameter space is thermodynamically supportive of large hail. Hodographs show a fairly straight, elongated hodograph with a little bit of low level curvature. Think the best threat for tornadoes will be along and near the boundary where low level helicity can be maximized. The supercells are expected to move quickly off to the east and grow upscale into a more linear feature where damaging winds will take over as the primary threat. Luckily, hydro concerns remain limited as storms are expected to form in areas that didn't see significant rainfall from yesterday's batch of storms. These storms should also be moving at a good clip which will limit the impacts of heavy rainfall in a given area. The environment is certainly favorable for some significant storms this afternoon and early evening with the Day 1 Enhanced Risk in place with significant hail and tornado probabilities in place across southwestern Wisconsin and northeastern Iowa.

Severe Storm Potential Wednesday

The severe threat for Wednesday will hinge a lot upon how much the airmass can recover from this afternoon/evening's storms. The airmass will remain persistently warm and moist as yet another surface low will move into Iowa, likely putting southeastern portions of our area in the warm sector - again. Ongoing showers and storms may inhibit how much we can destabilize by the afternoon. If we can destabilize and get enough diurnal heating, the environment would be supportive of strong to severe storms with around 1000 J/kg of CAPE. Shear profiles this far north don't look particularly impressive but low level helicity near the warm front may be enough to support a low tornado risk. Again, this will depend heavily on lingering convection tonight and into tomorrow morning with hopefully better consensus among models with the 00Z and 06Z suites.

Storms Ramp Back Up Friday

After a brief lull in activity for Thursday, we ramp back up into severe chances for Friday. A deep trough is expected to take shape over the Rockies late in the week. As this slides east, southwesterly flow is expected to increase across the area. At the surface, a bit of a complicated pattern is set to take shape with two semi-weak surface lows, one over the Northern Plains and another over the Central Plains. Out ahead of these lows, a broad warm sector will develop across much of the Mississippi River Valley. With increasing ascent from the upper trough and surface lift from a cold front that moves east, a line of storms is expected to develop sometime Friday west of our area. Steep mid level lapse rates and a strengthening low/mid level jet at 40-60 kts will support initial supercell development before storms form into a QLCS. Thermodynamic profiles show a broad area of 2000-3000 J/kg across our area with slightly curved and elongated hodographs. With all of this coming together, SPC has put our area in a Day 4 Slight Risk with an Enhanced Risk just off to our south and west, where shear and overall forcing looks a bit more robust.

Snow Showers This Weekend?

As the aforementioned surface low(s) move off to the north and east into Ontario by 12Z Saturday, the long draping cold front will have finally made its way through the area. With the low strengthening slightly, the pressure gradient will remain tight enough to allow strong cold air advection into the area early Saturday. While high temperatures Friday will be in the 70s areawide, highs by Saturday will have fallen 20-30 degrees into the low 40s to mid 50s. Model guidance is even indicating some the precipitation on the back side of the low could be a rain/snow mix or just all light snow. Which is a wild thing to think about after a week of 70+ degree temperatures but such is life in the midwest during spring. Any snow should not be impactful with no accumulations expected given that ground temperatures should support melting on contact.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1228 PM CDT Tue Apr 14 2026

IFR and MVFR ceilings will become VFR by mid-afternoon.

Scattered storms will develop along and south of the Interstate 90 by mid-afternoon and then move south by late afternoon. Some of these storms could be strong to severe.

Dense fog will develop tonight and continue into the mid-morning of Wednesday.

HYDROLOGY

Issued at 1254 PM CDT Tue Apr 14 2026

Widespread hydrologic concerns are not expected with this afternoon and evenings activity given the fast expected storm motion and overall impacted location being south of where the heaviest rain for yesterday's event has fallen. Given that SW Wisconsin is under threat, the main basin of concern would be the Kickapoo as it's notoriously flashy and could see rises into Action/Minor with this activity.

Flood watches and warnings continue for locations along the Black and Trempealeau Rivers primarily with other locations impacted including the Yellow River at Necedah and various spots along the Wisconsin River. The larger basins seem more at risk as we move through the rest of the week with continued chances for rain today, tomorrow, and Friday. None of these events look to provide particularly heavy rain but the repeated activity will likely cause river rises along area basins. Flash flooding is not of great concern either but rain rates with the strongest thunderstorms may support local ponding.

ARX WATCHES/WARNINGS/ADVISORIES

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