Flash flood watches were issued throughout central Maine Monday evening, according to the National Weather Service. The warnings were set to expire Tuesday morning.

Thunderstorms and rain were expected to be heavy overnight, and “may result in flash flooding washing out roads and causing rapid rises on area rivers and streams,” the service stated at 6:06 p.m.

Flooding was possible throughout Kennebec and Franklin counties, in southern Somerset county, interior Waldo County, and in Knox, Lincoln and Sagadahoc counties, the service said.

The Kennebec River in Skowhegan was expected to exceed flood flow rates at about 9 a.m. Tuesday and remain in a flood state until about 8 p.m. Wednesday, according to the service.

The river was expected to be at flood stage in Augusta by 8 p.m. Tuesday, and subside around 3 p.m. Wednesday, the service reported.