Flash Flood in Ferry County, Washington

Firefighters on the Williams Flats Wildfire reported numerous roads washed out due to heavy rain from a series of thunderstorms passing over the burn area. An estimated 2 inches of rain from persistent thunderstorms impacted the active fire site. Sixty four firefighters were stranded overnight when their access road was washed out by a flash flood during the evening of the 10th. They were successfully extracted the next morning using an alternate route.

The weather pattern on August 10th featured a very moist and unstable air mass with a passing upper level low pressure. These elements promoted widespread thunderstorms with heavy rain which produced Flash Flooding over potions of eastern Washington. Local observations indicated some of these slow moving storms produced from 1 to locally in excess of 5 inches of rain. Particularly hard hit was the Wenatchee area where flash flooding was reported in gulches and canyons emptying into the city. These floods produced severe damage to at least three mobile homes in Wenatchee.

Elsewhere heavy rains flooded sections of Highway 2 on the Waterville Plateau and the area around Elk and Chatteroy north of Spokane received up to 5 inches of rain from a stationary thunderstorm which produced scattered flooding of streets and driveways, water in basements and washouts on hillsides. There were also isolated reports of hail with diameters of up to 1 inch with some of these storms.