textproduct: La Crosse

KEY MESSAGES

- Numerous showers and thunderstorms are expected Friday afternoon with potential for a strong storm or two with gusty winds and hail.

- Low potential (30%) for moderate rain to impact portions of northeast Iowa and southwest Wisconsin Sunday.

- Additional showers and storms are possible, particularly during the afternoon and evening, on Monday (10%), Tuesday (60%), and Wednesday (30%). Severe storms are not expected.

DISCUSSION

Issued at 1159 PM CDT Thu Jun 18 2026

Showers and thunderstorms Friday afternoon

Strong shortwave currently over Saskatchewan will dive southeast today. While low level moisture is forecast to largely remain steady state given continued winds out of the west, temperature aloft should cool enough due to the approaching wave for convection to blossom this afternoon. Given the robust upper support, have moved PoPs upward from 19.01z NBM 30-60 values toward 60-70s for the majority of the CWA. As for hazards, while instability looks to be limited given total lack of moisture return (only a 10-40% chance to exceed 750 J/kg SBCAPE per 19.00z HREF), strong westerlies aloft should yield sfc-6km bulk shear around 60 knots, albeit with a linear hodograph shape. Therefore, would not be surprised to see some supercellular structures but an overall messy storm mode as storm dynamics would support readily splitting supercells. Primary risk looks to be from wind as downdrafts bring down stronger winds aloft and hail given the potential for additional residence time with rotating storms. That said, overall risk is limited (5%) due to aforementioned issues with instability and the relatively shallow boundary layer limiting top end wind risk.

Potential for moderate rain Sunday

Lee cyclone looks to develop in western Kansas Sunday and quickly move east into central Illinois as IA/MO/IL sit under the right entrance region of an upper jet. With surface ridging in place in the SE CONUS, robust moist advection will occur on the east side of this feature. Depending on the trajectory of the low, wrap-around moisture may advect over NE IA and SW WI and a decent amount of rain would result. That said, 18.12z LREF suggests only a 30% chance to reach 1" of rainfall in these areas, largely driven by the ECENS. Expect a sharp northern cutoff in rain - the same area with a 30% chance to reach 1" also has a 20% chance to end up with zero (0) rainfall. With 19.00z NAM bringing precip to the southern CWA, resisted urge to cut PoPs for now. As for severe storms, traditional ensemble probabilities and post-processing systems both strongly suggest these will remain to our south.

Additional shots and showers, storms into next week

Northwesterly flow aloft slowly returns into the middle of next week. With robust moisture return once again staying away, expect bouts of ordinary convection with any well-timed waves moving downstream during the afternoon. At this time, Tuesday appears to have the relatively higher probability for showers and thunderstorms (60%).

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 600 AM CDT Fri Jun 19 2026

VFR expected for much of the 19.12Z TAF period outside of thunder chances increasing from northwest to southeast through the afternoon and early evening, exiting east by tonight. Current confidence keeps PROB30 at both local TAF sites (KLSE/KRST).

ARX WATCHES/WARNINGS/ADVISORIES

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