Hail in Mason County, Illinois

As a deep area of low pressure tracked slowly northeastward across the Upper Midwest, a warm front surged northward through central Illinois on February 8th. Thanks to strong southerly flow in the wake of the front, near record high temperatures in the lower to middle 60s were observed. With modest instability in place and increasing deep-layer wind shear ahead of an approaching upper wave, scattered supercell thunderstorms developed across the Illinois River Valley during the late afternoon and evening. One of the cells produced an EF-1 tornado in northern Marshall County near Henry that tracked northeastward into Putnam County. Other storms dropped hail as large as quarters.