The third week of January brought very active winter weather to the Inland Northwest as a series of surface low pressures tracked along a stalled arctic air mass boundary laying near or over eastern Washington and north Idaho. Occasional feeds of Pacific moisture directed into this storm track lead to periodic heavy accumulations of snow across the region through the week.  During the whole week of repeated snow storms many northern valley locations received 2 to 3 feet of snow accumulation with mountain ski resorts reporting 4 to 5 feet of fresh powder.
The first surface low pressure system tracked through northern Washington and Idaho on January 11th and 12th. A stationary front followed by a cold front produced a  period of accumulating snow across the region. Only the lowest elevations of the Columbia River and Okanogan River Valleys received minor snow accumulations in the precipitation shadowed lee of the Cascades.
Over the East Slopes of the Cascades a persistent Puget Sound Convergence Zone after the cold front passage became focused on the Stevens Pass area for an extended period of time. Stevens Pass recorded 33 inches of snow during this storm. Highway 2 had to be closed at Stevens Pass due to multiple traffic accidents. The BNSF railway line was closed across the pass due to hundreds of trees toppled by heavy wet snow.
Elsewhere across northeast Washington and north Idaho over 25,000 customers lost power due to snow laden trees toppling into power lines.

Heavy Snow in SPOKANE AREA, WASHINGTON
From 10-JAN-20 10:00:00 to 11-JAN-20 03:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A weather spotter in Chattaroy reported 7.0 inches of new snow accumulation.

Heavy Snow in SPOKANE AREA, WASHINGTON
From 10-JAN-20 10:00:00 to 11-JAN-20 03:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A member of the public in Spokane's South Hill neighborhood reported 6.5 inches of new snow accumulation.

Heavy Snow in SPOKANE AREA, WASHINGTON
From 10-JAN-20 10:00:00 to 11-JAN-20 03:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A weather spotter in Spokane Valley reported 6.0 inches of new snow accumulation.

Heavy Snow in SPOKANE AREA, WASHINGTON
From 10-JAN-20 10:00:00 to 11-JAN-20 03:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A weather spotter 7 miles south of Tum Tum reported 6.3 inches of new snow accumulation.

Heavy Snow in NORTHEAST MOUNTAINS, WASHINGTON
From 10-JAN-20 22:00:00 to 12-JAN-20 04:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A member of the public 4 miles south of Newport reported 5.0 inches of snow accumulation from this storm.

Heavy Snow in NORTHEAST MOUNTAINS, WASHINGTON
From 10-JAN-20 22:00:00 to 12-JAN-20 04:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

A member of the public 5 miles southwest of Kettle Falls reported 5.0 inches of snow accumulation from this storm.

Heavy Snow in OKANOGAN HIGHLANDS, WASHINGTON
From 10-JAN-20 10:00:00 to 11-JAN-20 02:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A member of the public near Malo reported 5.0 inches of new snow accumulation.

Heavy Snow in WASHINGTON PALOUSE, WASHINGTON
From 10-JAN-20 11:00:00 to 11-JAN-20 02:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A weather Spotter in Pullman reported 4.5 inches of new snow accumulation.

Heavy Snow in NORTHEAST MOUNTAINS, WASHINGTON
From 10-JAN-20 22:00:00 to 12-JAN-20 04:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A member of the public in Ford reported 4.5 inches of snow accumulation from this storm.

Heavy Snow in OKANOGAN HIGHLANDS, WASHINGTON
From 10-JAN-20 10:00:00 to 11-JAN-20 02:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A weather spotter 4 miles west of Boyds reported 4.0 inches of new snow accumulation.

Winter Storm in EAST SLOPES NORTHERN CASCADES, WASHINGTON
From 10-JAN-20 21:00:00 to 12-JAN-20 22:00:00 (PST-8)
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Public

The BNSF railroad company reported the rail line across Stevens Pass was closed for two days due to hundreds of trees downed across the railroad due to heavy wet snow.

Heavy Snow in NORTHEAST MOUNTAINS, WASHINGTON
From 10-JAN-20 22:00:00 to 12-JAN-20 04:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A weather spotter 3 miles north of Loon Lake reported 8.0 inches of snow accumulation from this storm.

Heavy Snow in NORTHEAST MOUNTAINS, WASHINGTON
From 10-JAN-20 22:00:00 to 12-JAN-20 04:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Deer Park Fire/Rescue reported reported 10.0 inches of snow accumulation from this storm.

Winter Storm in EAST SLOPES NORTHERN CASCADES, WASHINGTON
From 10-JAN-20 23:00:00 to 12-JAN-20 22:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Highway 2 across Stevens Pass was closed due to heavy snow and freezing rain leading to multiple vehicle collisions during the afternoon and evening of January 12th.

Heavy Snow in SPOKANE AREA, WASHINGTON
From 10-JAN-20 10:00:00 to 11-JAN-20 03:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A member of the public near Dishman reported 8.0 inches of new snow accumulation.

Heavy Snow in NORTHEAST MOUNTAINS, WASHINGTON
From 10-JAN-20 22:00:00 to 12-JAN-20 04:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

An observer in Metaline Falls recorded 6.8 inches of snow accumulation from this storm.

Heavy Snow in NORTHEAST MOUNTAINS, WASHINGTON
From 10-JAN-20 22:00:00 to 12-JAN-20 04:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

The COOP observer at Boundary Dam recorded 11.0 inches of snow accumulation from this storm.

Heavy Snow in SPOKANE AREA, WASHINGTON
From 10-JAN-20 10:00:00 to 11-JAN-20 03:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

The observer at the Spokane International Airport recorded 7.0 inches of new snow accumulation.

Heavy Snow in NORTHEAST MOUNTAINS, WASHINGTON
From 10-JAN-20 22:00:00 to 12-JAN-20 04:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

An observer near Diamond Lake recorded recorded 11.0 inches of snow accumulation from this storm.

Heavy Snow in EAST SLOPES NORTHERN CASCADES, WASHINGTON
From 10-JAN-20 21:00:00 to 11-JAN-20 19:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

An observer 6 miles north of Winthrop recorded 5.5 inches of new snow accumulation.

Heavy Snow in WASHINGTON PALOUSE, WASHINGTON
From 10-JAN-20 11:00:00 to 11-JAN-20 02:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

The observer at Rosalia recorded 4.5 inches of new snow accumulation.

Heavy Snow in NORTHEAST BLUE MOUNTAINS, WASHINGTON
From 10-JAN-20 14:00:00 to 11-JAN-20 23:59:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The Bluewood Ski Resort reported 10 inches of new snow accumulation.

Heavy Snow in EAST SLOPES NORTHERN CASCADES, WASHINGTON
From 10-JAN-20 21:00:00 to 11-JAN-20 19:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

An observer 5 miles south of Peshastin recorded 10.0 inches of new snow accumulation.

Heavy Snow in EAST SLOPES NORTHERN CASCADES, WASHINGTON
From 10-JAN-20 21:00:00 to 11-JAN-20 19:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

An observer in Peshastin recorded 6.5 inches of new snow accumulation.

Heavy Snow in UPPER COLUMBIA BASIN, WASHINGTON
From 10-JAN-20 11:00:00 to 10-JAN-20 22:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

The observer at Odessa recorded 6.5 inches of new snow accumulation.

Heavy Snow in OKANOGAN HIGHLANDS, WASHINGTON
From 10-JAN-20 10:00:00 to 11-JAN-20 02:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

An observer 8 miles north of Republic recorded 5.1 inches of new snow accumulation.

Heavy Snow in EAST SLOPES NORTHERN CASCADES, WASHINGTON
From 10-JAN-20 21:00:00 to 11-JAN-20 19:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

An observer 12 miles north of Leavenworth recorded 7.5 inches of new snow accumulation.

Heavy Snow in EAST SLOPES NORTHERN CASCADES, WASHINGTON
From 10-JAN-20 21:00:00 to 11-JAN-20 19:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

An observer 12 miles northwest of Entiat recorded 4.6 inches of new snow accumulation.

Heavy Snow in SPOKANE AREA, WASHINGTON
From 10-JAN-20 10:00:00 to 11-JAN-20 03:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

The observer at Davenport recorded 6.3 inches of new snow accumulation from this storm.

Heavy Snow in EAST SLOPES NORTHERN CASCADES, WASHINGTON
From 10-JAN-20 21:00:00 to 11-JAN-20 21:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

The observer at Holden Village recorded 8.4 inches of new snow accumulation.

Heavy Snow in UPPER COLUMBIA BASIN, WASHINGTON
From 10-JAN-20 11:00:00 to 10-JAN-20 22:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

An observer at Almira recorded 4.5 inches of new snow accumulation.

Heavy Snow in UPPER COLUMBIA BASIN, WASHINGTON
From 10-JAN-20 11:00:00 to 10-JAN-20 22:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

An observer near Grand Coulee recorded 4.0 inches of new snow accumulation.

Heavy Snow in EAST SLOPES NORTHERN CASCADES, WASHINGTON
From 10-JAN-20 21:00:00 to 11-JAN-20 19:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

The observer at Mazama recorded 7.0 inches of new snow accumulation.

Heavy Snow in EAST SLOPES NORTHERN CASCADES, WASHINGTON
From 10-JAN-20 21:00:00 to 11-JAN-20 19:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

The observer at Plain recorded 7.3 inches of new snow accumulation.

Heavy Snow in EAST SLOPES NORTHERN CASCADES, WASHINGTON
From 10-JAN-20 21:00:00 to 11-JAN-20 19:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

The observer at Stehekin recorded 10.0 inches of new snow accumulation.

Heavy Snow in WASHINGTON PALOUSE, WASHINGTON
From 10-JAN-20 11:00:00 to 11-JAN-20 02:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

The observer at Pullman recorded 4.0 inches of new snow accumulation.

Heavy Snow in NORTHEAST MOUNTAINS, WASHINGTON
From 10-JAN-20 22:00:00 to 12-JAN-20 04:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

The COOP observer at Northport recorded 7.9 inches of snow accumulation from this storm.

Heavy Snow in UPPER COLUMBIA BASIN, WASHINGTON
From 10-JAN-20 11:00:00 to 10-JAN-20 22:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

The observer at Ritzville recorded 4.2 inches of new snow accumulation.

Heavy Snow in SPOKANE AREA, WASHINGTON
From 10-JAN-20 10:00:00 to 11-JAN-20 03:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A member of the public near Colbert reported 8.3 inches of new snow accumulation.

Heavy Snow in SPOKANE AREA, WASHINGTON
From 10-JAN-20 10:00:00 to 11-JAN-20 03:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

A NWS Spokane staff member in northwest Spokane reported 8.0 inches of new snow accumulation.

Heavy Snow in SPOKANE AREA, WASHINGTON
From 10-JAN-20 10:00:00 to 11-JAN-20 03:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A member of the public near Mead reported 7.5 inches of new snow accumulation.

Heavy Snow in NORTHEAST MOUNTAINS, WASHINGTON
From 10-JAN-20 22:00:00 to 12-JAN-20 04:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A member of the public in Deer Park reported 7.0 inches of snow accumulation from this storm.