The Storm Prediction Center has issued a Severe Thunderstorm Watch effective until 6am Monday morning for the following counties, Benton, Cedar, Clinton, Des Moines, Henry, Iowa, Jefferson, Johnson, Keokuk, Lee, Linn, Louisa, Muscatine, Scott, Van Buren and Washington. Thunderstorms over southern Iowa will move slowly northward along and ahead of a advancing warm front. The main threats with these storms will likely be large hail and some isolated strong gusty winds. Heavy rainfall is also possible. There will be more rounds of severe weather later on Monday.