A tornado watch has been issued until 1am for the following counties, Bremer, Butler, Cerro Gordo, Franklin, Hancock, Humboldt, Kossuth, Winnebago, Worth, Wright, Allamakee, Chickasaw, Clayton, Fayette, Floyd, Howard, Mitchell and Winneshiek. Thunderstorms are rapidly developing across the northern part of the state. There has been already one storm tornado warned in south central Minnesota north of Albert Lea. Large hail, damaging winds and isolated tornadoes will be possible in and around the watch area through this evening into the overnight.