FXUS63 KARX 180609 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 109 AM CDT Mon May 18 2026 .KEY MESSAGES... - Severe weather possible between 7 PM and 1 AM tonight. All hazards are possible mainly west of the Mississippi River. - Another round of severe weather possible on Monday night between 9 PM and 4 AM. The main threat will be damaging winds. With isolated threats of hail and maybe a few QLCS tornadoes. && .DISCUSSION... Issued at 1257 PM CDT Sun May 17 2026 This Afternoon The remnant MCV which brought rain mainly south of Interstate 94 will continue to move northeast away from the area this afternoon. As it does, the showers and isolated storms currently along Interstates 90 and 94 will move east northeast away from the area. Additional rainfall amounts will be up to a half inch. As a warm front gradually lifts northward, temperatures along and south of Interstate 94 will warm into the 60s and lower 70s, and into 60s north of this Interstate. This will result in surface-based CAPES climbing into the 1000 to 2500 J/kg along and south of Interstate 90 by 7 pm. Tonight Late this afternoon and evening, 2-3K J/kg CAPES will develop ahead of a squall line moving east across eastern South Dakota, eastern Nebraska, northern Iowa, and southern Minnesota. with 0-6 km shear approaching 40 knots, there could potentially be some supercells located along the line (these would likely stay west of the Upper Mississippi River Vally) and along the warm front near the Minnesota and Iowa boarder. In addition to the deep shear, there is 200-300 EHI along the Minnesota and Iowa boarder and downdraft CAPEs up to 1K J/kg. The discrete supercells ahead of the squall line would be capable of producing wet microbursts, large hail, and isolated tornadoes between 7 PM and 10 PM in southeast Minnesota and northeast Iowa. The threat will then shift to more damaging winds and maybe a few QLCS tornadoes as the squall line moves into southeast Minnesota and northeast Iowa between 10 PM and 11 PM. This line will then gradually weaken as the instability wanes. The severe weather threat will likely wane by 1 AM Monday. Monday night A cold front will move east through the area. There will be 1-2K J/kg CAPES ahead of this front. With much of the deep (0-6 km) shear located post frontal, not anticipating any supercells. As a result, if there is severe weather, it would be located along the cold front as a squall line. The primary threat would be damaging winds with secondary threats as hail and QLCS tornadoes. Timing looks to be rather similar tonight with the squall line moving into northeast Iowa and southeast Minnesota between 9 PM and 10 PM. It will exit the area between 2 AM and 4 AM. By this time, the winds will likely be sub-severe. Friday into Saturday A shortwave trough will move east through the area. This will result in another round of showers and isolated storms. With CAPES less than 250 J/kg and 0-3 km and 0-6 km shear less than 25 knots, not anticipating any organized severe weather at this time. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1242 AM CDT Mon May 18 2026 Line of decaying storms seen shifting east through local forecast area, over Mississippi River Valley at 18.06Z TAF issuance. Strong winds along and behind this line will be main impact besides scattered embedded thunder. Strong winds persist behind this line for the next couple of hours. MVFR-IFR ceilings with MVFR visibilities possible with ongoing early morning rain. VFR expected through the late morning into the early afternoon before thunder chances increase from southwest to northeast again Monday evening and night. Storms quickly progress from southwest to northeast with damaging winds as main severe hazard. Storms exit the area with frontal passage overnight into Tuesday morning. && .HYDROLOGY... Issued at 106 AM CDT Sun May 17 2026 One to two inch totals are still forecast across the area, with areas further west more favored for the 2 inch totals. This will likely not cause river flooding, only within bank rises. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Boyne AVIATION...JAR HYDROLOGY...Baumgardt