textproduct: La Crosse

KEY MESSAGES

- While the local severe weather threat is decreasing, still cannot fully rule out an isolated severe storm before 8pm this afternoon. The tornado threat is quite conditional but still non-zero.

- Cooler and drier for the remainder of the work week with highs in the 50s and lows in the 30s. Warming up next weekend.

DISCUSSION

Issued at 1247 PM CDT Mon Apr 27 2026

This Afternoon: Convective Evolution Details

A 998-mb quasi-barbell surface low structure was noted along a cold front advancing through southwestern MN and northwestern IA early this afternoon, with broad east to southeast flow ahead of these low centroids and veering flow on the south side of these lows behind a warm front. A corridor of clearing developed within the dry slot ahead of the cold front, allowing for some airmass recovery in the wake of our morning convection. While only a few degrees, this insolation was enough to trigger convective initiation along the front shortly before midday in northwestern Iowa. With the 850-mb jet already displaced to the east and surface flow veered to the SSW ahead of the front, the storms are encountering a vertical wind profile unfavorable for sustained updraft longevity, featuring compressed and complex hodographs per HRRR/RAP profiles.

An additional line of convergence along the de-facto warm front lifting into northeastern Iowa could also spark showers and storms over the next few hours. While these storms will develop in a more favorable wind profile featuring looped and elongated hodographs, the lack of daytime heating ahead of the line will result in struggling updrafts if any do manage to get going at all. Thus is the story of our current weather setup--two potential areas of convective development, but neither has both the favorable thermodynamic and kinematic profiles in place to support an organized severe weather threat.

While a very low probability (< 10%) given the relatively progressive nature of the low/front, should sufficient clearing take place ahead of the front, there could be enough 0-3-km MLCAPE and surface vorticity pooled along the front to generate landspout tornadoes with any convection rooted along the boundary. However, the degree of recovery ahead of the front will be key and the window of opportunity for such a setup will be only an hour or two at any given location.

The threat for severe weather departs once the cold front passes, which looks to be between 3pm and 8pm tonight.

Rest of the Week: Cooler and Drier

Broad longwave troughing with multiple embedded shortwaves resides over the north-central U.S. through the remainder of the week, keeping a continued fetch of polar air in place and temperatures roughly 10 degrees below normal. Several of these aforementioned undulations bring periods of clouds and possibly light showers from Tuesday through Thursday, but the probabilities for measurable precipitation is quite low and impacts should be minimal. Lows will be dictated by cloud cover and winds with the surface high pressure centroid remaining upstream, but the need for Frost/Freeze headlines will increase from Tuesday through Friday nights. The pattern shifts for next weekend as ridging builds in, allowing for more seasonal temperatures to creep northward.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1156 PM CDT Mon Apr 27 2026

MVFR cigs overnight will improve to VFR by mid-morning as sky cover becomes bkn to sct. Winds will remain elevated at around 12-18 kt with gusts up to 30 kts during the morning, but will gradually diminish during the afternoon and into the evening while remaining northwesterly.

ARX WATCHES/WARNINGS/ADVISORIES

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