A strong low pressure system moved up from the southwest and overran an existing cold, deep airmass.  Surface temperatures as precipitation started were just above freezing, but with heavy showers, precipitation quickly turned over to snow during the early evening hours. Embedded thunderstorms enhanced snowfall rates around the Portland Metro area for a crippling snowstorm Tuesday evening.  Snow continued to fall through Wednesday morning.

Heavy Snow in UPPER HOOD RIVER VALLEY, OREGON
From 10-JAN-17 13:30:00 to 11-JAN-17 11:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Hood River and Parkdale reported 8 to 12 inches of snow. Heavy packed snow led to leaking roofs, broken pies and gutters on homes across the area.  Hood River also required additional emergency snow plowing. I-84 was closed for around 15 hours due to hazardous road conditions.

Heavy Snow in WESTERN COLUMBIA RIVER GORGE, OREGON
From 10-JAN-17 13:30:00 to 11-JAN-17 11:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

A local TV meteorologist reported 4 inches in Corbett, and there was another report of 4 inches of snow in Gresham. Further east in the Gorge, 8-12 inches fell.  Seems likely with 8-12+ inches east and west of this zone that somewhere near Cascade Locks got at least 4-6 inches of snow. I 84 was closed for 15 hours due to hazardous road conditions.

Heavy Snow in CENTRAL WILLAMETTE VALLEY, OREGON
From 10-JAN-17 11:30:00 to 11-JAN-17 05:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Snowfall of 1 to 2 inches were reported in the Salem area and up to 11 inches at Chehalem Mountain near Newberg.

Heavy Snow in COAST RANGE OF NW OREGON, OREGON
From 10-JAN-17 13:00:00 to 11-JAN-17 11:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Storm spotter in Banks reported 12 inches of snow.

Heavy Snow in LOWER COLUMBIA, OREGON
From 10-JAN-17 16:00:00 to 11-JAN-17 11:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

There were reports of 4 to 8 inches of snow around Kelso and Longview across the river.

Heavy Snow in GREATER  PORTLAND METRO AREA, OREGON
From 10-JAN-17 13:30:00 to 11-JAN-17 11:00:00 (PST-8)
Property damage: 280.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

A high-impact snowstorm for the Portland Metro area, which caused hazardous travel, power outages and other challenges.   Many cars were stuck on the road during the evening rush hour. Widespread downed or broken trees due to snow loading, leading to multiple power outages. There was one report on social media of a car smashed by a downed tree which was loaded with snow. Snow amounted to 5 to 15.5 inches across the Portland Metro, with highest amounts in the West Hills.  Heavy snow caused the roof of a warehouse to collapse in Hillsboro.

Heavy Snow in CENTRAL COLUMBIA RIVER GORGE, OREGON
From 10-JAN-17 13:30:00 to 11-JAN-17 11:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Hood River and Parkdale reported 8 to 12 inches of snow. Heavy packed snow led to leaking roofs, broken pies and gutters on homes across the area. Hood River also required additional emergency snow plowing. I-84 was closed for around 15 hours due to hazardous road conditions.