A nearly stationary upper level low pressure area parked near Brookings, Oregon brought abundant moisture across eastern Washington. This combined with daytime heating to produce a few severe thunderstorms and locally heavy rainfall.  The heavy rainfall caused flash flooding and landslides in several areas. The upper level low moved north away from the area late on July 20.

Debris Flow in LOWER COLUMBIA BASIN, WASHINGTON
From 16-JUL-12 06:10:00 to 16-JUL-12 06:10:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Hail in BENTON, WASHINGTON
From 20-JUL-12 12:00:00 to 20-JUL-12 12:00:00 (PST-8)
Location: FINLEY
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Radio operator reported hail damaged 3 vehicles and broke 2 house windows.

Flash Flood in YAKIMA, WASHINGTON
From 20-JUL-12 11:40:00 to 20-JUL-12 11:40:00 (PST-8)
Location: SUNNYSIDE BROADVIEW
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Newspaper

Unoccupied mobile home washed away. Six mile stretch of Highway 241 closed until 7 pm.

Hail in YAKIMA, WASHINGTON
From 20-JUL-12 11:35:00 to 20-JUL-12 11:35:00 (PST-8)
Location: SUNNYSIDE
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in WALLA WALLA, WASHINGTON
From 20-JUL-12 13:03:00 to 20-JUL-12 13:08:00 (PST-8)
Location: KOOSKOOSKIE
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Radio operator was at the Table Rock Fire Lookout.

Hail in COLUMBIA, WASHINGTON
From 20-JUL-12 13:30:00 to 20-JUL-12 13:30:00 (PST-8)
Location: MIDWAY
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

At Camp Wooten State Park, hail ranged from quarter sized up to ping pong ball and was accompanied by heavy rainfall.

Debris Flow in KITTITAS VALLEY, WASHINGTON
From 17-JUL-12 17:00:00 to 17-JUL-12 17:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

A mudslide about 100 feet long and 15 feet deep was reported on Highway 821, which is the Yakima River Canyon Highway between Ellensburg and Selah.

Heavy Rain in KITTITAS, WASHINGTON
From 17-JUL-12 18:10:00 to 17-JUL-12 19:10:00 (PST-8)
Location: ELLENSBURG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

One inch of rainfall observed in 1 hour.

Hail in YAKIMA, WASHINGTON
From 20-JUL-12 11:35:00 to 20-JUL-12 11:35:00 (PST-8)
Location: SUNNYSIDE
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Hail accompanied by heavy rainfall.

Hail in FRANKLIN, WASHINGTON
From 20-JUL-12 12:00:00 to 20-JUL-12 12:10:00 (PST-8)
Location: LEVEY
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Flash Flood in WALLA WALLA, WASHINGTON
From 16-JUL-12 00:00:00 to 16-JUL-12 06:00:00 (PST-8)
Location: TOUCHET
Flood cause: Heavy Rain
Property damage: 1.25M
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorms training from south southwest to north northeast over the narrow path produced an estimated 1 to 2 inches of rainfall and caused flash flooding and mud slides.  A parked pickup truck was completely submerged.  Over a dozen county roads were damaged.

Hail in YAKIMA, WASHINGTON
From 20-JUL-12 11:40:00 to 20-JUL-12 11:40:00 (PST-8)
Location: SUNNYSIDE BROADVIEW
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement