The National Weather Service in Des Moines has issued a Flash Flood Watch in effect until 6am Tuesday morning for the following counties: Black Hawk, Bremer, Butler, Calhoun, Cerro Gordo, Emmet, Franklin, Grundy, Hamilton, Hancock, Hardin, Humboldt, Kossuth, Palo Alto, Pocahontas, Sac, Webster, Winnebago, Worth, Wright