An upper level disturbance moving north on the back side of an upper level ridge combined with a very moist atmosphere to produce local severe thunderstorms and flooding.

Hail in JEFFERSON, OREGON
From 23-APR-12 17:26:00 to 23-APR-12 17:26:00 (PST-8)
Location: ASHWOOD
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in WASCO, OREGON
From 23-APR-12 18:00:00 to 23-APR-12 18:00:00 (PST-8)
Location: CLARNO
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Heavy Rain in MORROW, OREGON
From 23-APR-12 19:05:00 to 23-APR-12 19:40:00 (PST-8)
Location: HEPPNER
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Three quarters of an inch of rainfall fell in a 35 minute period.

Thunderstorm Wind in UMATILLA, OREGON
From 23-APR-12 20:04:00 to 23-APR-12 20:04:00 (PST-8)
Location: ECHO COONS ARPT
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Thunderstorm Wind in UMATILLA, OREGON
From 23-APR-12 20:05:00 to 23-APR-12 20:05:00 (PST-8)
Location: HERMISTON
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Rocky Heights Elementary School had roofing material, metal flashing, and insulation peeled back on the roof on the south side of the gymnasium by thunderstorm winds.  Heavy rainfall caused interior water damage.

Thunderstorm Wind in UMATILLA, OREGON
From 23-APR-12 20:42:00 to 23-APR-12 20:42:00 (PST-8)
Location: UMATILLA
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Flash Flood in GILLIAM, OREGON
From 23-APR-12 20:00:00 to 23-APR-12 20:00:00 (PST-8)
Location: MAYVILLE
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Public

Flash flood washed out Armstrong Road and Thirty mile road and moved large amounts of debris including large boulders.  A fiber optic communications line was cut which caused phone outage for hundreds of customers.  A cow and calf were swept away in the flash flood.

Thunderstorm Wind in UMATILLA, OREGON
From 23-APR-12 20:15:00 to 23-APR-12 20:15:00 (PST-8)
Location: HERMISTON
Magnitude: 52.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Newspaper

Thunderstorm winds downed a large elm tree onto a house and deck.

Flash Flood in MORROW, OREGON
From 23-APR-12 19:30:00 to 23-APR-12 21:00:00 (PST-8)
Location: HEPPNER
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Newspaper

Heavy rainfall caused flash flooding in several areas of Heppner, including residences, the elementary school, sewage treatment plant, city shop, a bank, and the newspaper office. Roadways were also flooded and debris cleanup had to ensue in 10 spots.

Heavy Rain in MORROW, OREGON
From 23-APR-12 18:55:00 to 23-APR-12 19:55:00 (PST-8)
Location: HEPPNER
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Rainfall of 1.23 inches was reported in a 1 hour period.

Hail in JEFFERSON, OREGON
From 23-APR-12 16:44:00 to 23-APR-12 16:44:00 (PST-8)
Location: CULVER CHINOOK ARPT
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in UMATILLA, OREGON
From 23-APR-12 20:01:00 to 23-APR-12 20:01:00 (PST-8)
Location: HERMISTON ARPT
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

The strong wind was accompanied by 0.86 inches of rainfall in 50 minutes.

Hail in WHEELER, OREGON
From 23-APR-12 17:30:00 to 23-APR-12 17:30:00 (PST-8)
Location: FOSSIL
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Observer also reported minor flooding on Butte Creek.  The hail caused damage to an RV.