Hail in Williamson County, Illinois

Hail to the size of quarters fell in Carterville.

An upper-level disturbance moved northeast through the Mid-Mississippi Valley through the afternoon, as the associated surface low lifted northeast across Michigan. The best instability was slightly elevated (MLCAPE values near 1000J/kg vs MUCAPE values 1500-2000J/kg), and the effective shear was barely 25kts. A subtle surface trough helped to get isolated storms going around 1500CST and they moved east southeast through southern Illinois through around 1900CST. One very strong storm produced hail up to the size of golf balls in Jackson County, and went on to produce hail up to the size of quarters from Carterville to Marion in Williamson County. Other strong storms produced smaller hail over portions of Union, Saline, and Wayne Counties.