Widespread Storm Clusters Bring Destructive Winds and Local Flash Flood Risk

Overview

• Over the weekend convective clusters and long‑lived MCSs produced verified severe gusts including 70–80 mph reports and prompted SPC warnings that 80–100 mph gusts were possible in parts of South Dakota.
• The Storm Prediction Center and Weather Prediction Center issued multiple mesoscale discussions and watches as clusters grew upscale into bowing lines and MCSs that have produced destructive straight‑line winds and large hail.
• Forecasters highlighted an ongoing localized flash‑flood threat across parts of central Illinois, Indiana and Kentucky where extremely high instability (MLCAPE locally 4,500–6,000 J/kg) and moisture (PWATs over 2 inches) can yield efficient rates near 3 inches per hour and quick 2–4 inch totals.
• Meteorologists say the main drivers are very moist low levels, steep midlevel lapse rates, and 30–50 kt effective shear that let hail‑producing supercells rapidly evolve into cold‑pool‑driven MCSs that generate violent downbursts and training heavy rain.
• Communities in the threatened corridors should follow local NWS offices for warnings, prepare for power outages and flooded roads, and expect the risk to persist into Monday with additional watch issuances possible.