A SEVERE THUNDERSTORM WARNING has been issued for northeast Rock County and northwest Walworth County in southeast Wisconsin until 8:45pm. A severe storm located over Whitewater, WI was moving east at 10mph. This storm is capable of producing quarter sized hail. Quarter sized hail was reported in Whitwater, WI. In addition to the storm moving into Walworth County, an outflow boundary has developed and is currently moving south through central Walworth County. This could be the focal point for a few additional thunderstorms to develop along within the next hour or two. Most of the storm activity will be moving to the east and southeast, impacting areas primarily east of Rockford, but could come close to eastern Boone and McHenry Counties after 10pm.
Since the storms are slow moving – given the weaker winds aloft – very heavy rainfall will also be a threat. A Flood Advisory has been issued for northeast Rock County until 11pm Friday as storms just north of the area have produced rainfall amounts between one to two inches.