An eastward-moving upper level trough and associated area of surface low pressure moved across northwest Oregon and southwest Washington September 17-18, resulting in fairly widespread showers and thunderstorms beginning late in the afternoon of the 17th through most of the day on the 18th.  One severe thunderstorm developed southeast of Salem, OR during the overnight hours of Sept. 17-18, and moved northward across the eastern Willamette Valley and Cascade Foothills before eventually weakening over northeast sections of the Portland metro area. This storm produced hail to near 1 inch in diameter, wind damage, and locally heavy rain with minor street flooding. Other thunderstorms developed over southwest Washington during the afternoon and evening of the 18th, producing heavy rainfall and some local flooding.

Heavy Rain in LANE, OREGON
From 17-SEP-20 23:00:00 to 18-SEP-20 23:00:00 (PST-8)
Location: DANEBO
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

This is a 24 hour precipitation total.

Heavy Rain in LANE, OREGON
From 17-SEP-20 00:54:00 to 18-SEP-20 00:54:00 (PST-8)
Location: (EUG)EUGENE SWEET AR
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

This is the Eugene Airport ASOS report.

Heavy Rain in LINN, OREGON
From 17-SEP-20 16:30:00 to 18-SEP-20 16:30:00 (PST-8)
Location: SODAVILLE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

This is the 16 hour rain total.

Hail in MARION, OREGON
From 18-SEP-20 01:15:00 to 18-SEP-20 01:18:00 (PST-8)
Location: SUBLIMITY
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail up to the size of pennies accumulated up to 2 inches deep on the ground.

Hail in LINN, OREGON
From 18-SEP-20 00:50:00 to 18-SEP-20 00:55:00 (PST-8)
Location: SCIO
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Penny to nickel size hail accumulated on the ground.  Report from social media.

Thunderstorm Wind in MARION, OREGON
From 17-SEP-20 00:15:00 to 18-SEP-20 00:15:00 (PST-8)
Location: (SLE)MCNARY FLD SALE
Magnitude: 45.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Social Media

A 6-8 inch diameter tree branches blown down.

Flood in LINN, OREGON
From 17-SEP-20 00:55:00 to 18-SEP-20 00:55:00 (PST-8)
Location: LEBANON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

A video of street flooding was posted on social media.

Thunderstorm Wind in MARION, OREGON
From 18-SEP-20 00:15:00 to 18-SEP-20 00:15:00 (PST-8)
Location: ST PAUL
Magnitude: 45.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Public

Report of several small to medium size tree branches blown down.

Thunderstorm Wind in LINN, OREGON
From 18-SEP-20 00:36:00 to 18-SEP-20 00:36:00 (PST-8)
Location: LEBANON
Magnitude: 50.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Social Media

Photos of a 4-8 inch diameter tree limbs blown down and an uprooted tree.

Thunderstorm Wind in LINN, OREGON
From 18-SEP-20 00:37:00 to 18-SEP-20 00:37:00 (PST-8)
Location: WHITAKER
Magnitude: 50.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Social Media

An empty tractor trailer was blown over.

Thunderstorm Wind in LINN, OREGON
From 18-SEP-20 00:45:00 to 18-SEP-20 00:45:00 (PST-8)
Location: GRIGGS
Magnitude: 50.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Multiple trees snapped about 15-20 feet above the surface. Multiple power lines down and a metal shed severely damaged.

Heavy Rain in CLACKAMAS, OREGON
From 17-SEP-20 02:20:00 to 18-SEP-20 02:20:00 (PST-8)
Location: MACKSBURG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Rainfall total of 1.67 inches. Also measured a peak wind gust of 47 mph.

Heavy Rain in POLK, OREGON
From 17-SEP-20 01:15:00 to 18-SEP-20 01:15:00 (PST-8)
Location: PINCKNEY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Station EW7604 in Salem.

Heavy Rain in MARION, OREGON
From 17-SEP-20 01:05:00 to 18-SEP-20 01:05:00 (PST-8)
Location: JEFFERSON
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Lots of precipitation.

Heavy Rain in MARION, OREGON
From 17-SEP-20 01:15:00 to 18-SEP-20 01:15:00 (PST-8)
Location: SUBLIMITY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Lots of rain fall from the public.

Heavy Rain in MARION, OREGON
From 17-SEP-20 01:50:00 to 18-SEP-20 01:50:00 (PST-8)
Location: SILVER FALLS CITY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

A CoCoRaHS report of significant rainfall.

Heavy Rain in MARION, OREGON
From 17-SEP-20 06:00:00 to 18-SEP-20 06:00:00 (PST-8)
Location: QUINABY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

This is an 8 hour rainfall total.

Heavy Rain in POLK, OREGON
From 17-SEP-20 01:30:00 to 18-SEP-20 01:30:00 (PST-8)
Location: MC COY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Station 2711D 4 miles WSW of Wheatland.

Heavy Rain in CLACKAMAS, OREGON
From 17-SEP-20 03:30:00 to 18-SEP-20 03:30:00 (PST-8)
Location: BATTIN
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Rainfall amounts of 1.86 inches.

Heavy Rain in MARION, OREGON
From 17-SEP-20 01:36:00 to 18-SEP-20 01:36:00 (PST-8)
Location: ROBERTS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Station AU762 in Salem.

Heavy Rain in POLK, OREGON
From 17-SEP-20 01:20:00 to 18-SEP-20 01:20:00 (PST-8)
Location: PINCKNEY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Station FW8313 in Salem.

Heavy Rain in POLK, OREGON
From 17-SEP-20 07:04:00 to 18-SEP-20 07:04:00 (PST-8)
Location: PINCKNEY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Pea sized hail and rain reported.