The Storm Prediction Center has issued a Severe Thunderstorm Watch effective until 4am Sunday morning for the following counties, Cedar, Clinton, Delaware, Dubuque, Jackson, Johnson, Jones, Linn, Louisa, Muscatine, Scott, Washington, and Carroll (IL), Jo Daviess (IL), Mercer (IL), Rock Island (IL), and Whiteside (IL). Thunderstorms have developed across the eastern counties of the state and are tracking to the east and southeast at about 35-40mph. Hail up to the size of quarters or larger will be the main threat with these storms along with cloud to ground lightning and brief heavy rain.