WINTHROP - The National Weather Service has put a flash flood warning in effect for Sept. 4-6 in Okanogan County.
Thunderstorms with heavy rainfall are possible along the east slopes of the Cascade Mountains and could cause rapid runoff and flash flooding, the National Weather Service said.
Debris flows are also possible in and below areas burned in 2012 and 2013 wildfires.
Affected areas include Winthrop, Twisp, Methow, Conconully and Mazama.
Floods and debris flows can be very dangerous, the National Weather Service said.