Supercells Looming Southeast Minnesota into Central Wisconsin with Large Hail Threat — SevereWX

SPC Mesoscale Discussion Highlights Emerging Severe Threat

Afternoon visible satellite imagery shows a robust cumulus field building along a plume of rich low-level moisture stretching from near Rochester, MN, into central Wisconsin around Marshfield. SPC's Mesoscale Discussion 1400 flags a conditional risk for severe thunderstorms capable of large hail (1-1.75 inches) and damaging winds (55-70 mph), with supercell structures possible if storms take hold.

High instability fuels the setup: objective analysis reveals MLCAPE of 3500-4500 J/kg and negligible convective inhibition near the surface in this zone. However, a lack of strong lift or sharp boundaries leaves storm initiation uncertain. Vertical shear from the 18Z Green Bay sounding supports supercells as the primary mode, starting with significant hail before potential cold pool mergers ramp up wind threats into evening.

Watch issuance probability sits at 60% for southeast Minnesota into central and northern Wisconsin through around 6 PM CDT. Peak hazards include tornadoes up to 90 mph, but the focus remains on hail and gusts.

This setup ties into broader Northern Plains patterns, with recent Slight Risks evolving across Minnesota. Storms that fire could impact populated areas—monitor radar closely.

Stay prepared: Keep NOAA Weather Radio on, have multiple alert sources, and know your safe spot for large hail or strong winds. Check SPC updates at severeweather.net for the latest.