Modified arctic air moved into the region followed by a series of moderate to strong upper level storm systems riding on a moist subtropical jet stream. The result was widespread heavy snow and local high winds. Freezing rain and sleet accumulated to between 1/4 and 1/2 inch over the lower elevations.
On January 17 and 18, snowfall amounts reported in inches included Waitsburg (6), 5 miles north northwest of Wiley City (6), 18 miles west northwest of West Richland (5), 8 miles west northwest of Connell (4), 2 miles west of Yakima (5), Toppenish (6), 1 mile southwest of Yakima (5), 5 miles north northwest of Centerville (15), 9 miles northwest of Roslyn (23), 3 miles north northeast of Ellensburg (4), Yakima (4), 7 miles northeast of Goldendale (14.5), 4 miles east northeast of White Salmon (18), 1 mile south southwest of Yakima (4), Cle Elum (7), Dayton (7.5), Ski Bluewood (18), Goldendale (12), 1 mile west northwest of White Salmon (17), Glenwood (10), 1 mile east of Walla Walla (5), 5 miles north of White Salmon (10.2), Mount Adams Ranger Station (17), Snowden (18), Easton (14), Tampico (11), 2 miles east south of West Valley (5.5), 4 miles east northeast of Yakima (4),  Waitsburg (7), Richland (6), 15 miles northeast of Pasco (7.5), 10 miles east of Goldendale (13), 1 mile west of Toppenish (5), Kennewick (7.8), 3 miles northeast of College Place (4), West Richland (7), 5 miles south of Sunnyside (5), 20 miles west of Prescott (7), Selah (5), White Salmon (16), 6 miles east of White Swan (5.5), West Valley (7), Sunnyside 4.5), 10 miles north of Pasco (4), 1 mile southwest of Ellensburg (4), and 2 miles northeast of Husum (10.2).
On January 19-20, another surge of subtropical Pacific moisture moved over the cold air with a widespread mixture of precipitation. The lower elevations received freezing rain mixed at times with sleet and snow.  The higher elevations received heavy snowfall. The storm caused numerous vehicle accidents with injuries, downed tree branches, power outages, and closed roads and schools.
Ice accumulation reported in inches included Kennewick (.5), 1 mile west of Patterson (.25), Dayton (.5), Walla Walla (.5), 3 miles northeast of Dallesport (.38), 1 mile west northwest of White Salmon (.25).
Snowfall amounts reported in inches included 8 miles southeast of Cliffdell (13), 5 miles west southwest of Yakima (4.5), Yakima (4), Connell (4.5), 2 miles northwest of Ellensburg (5.8), Sunnyside (4.1), Glenwood (8), and 7 miles west of Fruitvale (7).

Heavy Snow in BLUE MOUNTAIN FOOTHILLS, WASHINGTON
From 17-JAN-12 22:00:00 to 18-JAN-12 15:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Heavy Snow in EAST COLUMBIA RIVER GORGE, WASHINGTON
From 17-JAN-12 19:00:00 to 18-JAN-12 11:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Heavy Snow in EAST SLOPES OF THE WASHINGTON CASCADES, WASHINGTON
From 16-JAN-12 16:00:00 to 18-JAN-12 06:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Heavy Snow in LOWER COLUMBIA BASIN, WASHINGTON
From 18-JAN-12 01:30:00 to 18-JAN-12 13:30:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Heavy Snow in NORTHWEST BLUE MOUNTAINS, WASHINGTON
From 17-JAN-12 18:00:00 to 18-JAN-12 14:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Heavy Snow in SIMCOE HIGHLANDS, WASHINGTON
From 17-JAN-12 05:30:00 to 18-JAN-12 11:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Winter Storm in BLUE MOUNTAIN FOOTHILLS, WASHINGTON
From 19-JAN-12 04:00:00 to 19-JAN-12 19:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Heavy Snow in YAKIMA VALLEY, WASHINGTON
From 18-JAN-12 02:00:00 to 18-JAN-12 14:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Winter Storm in EAST COLUMBIA RIVER GORGE, WASHINGTON
From 19-JAN-12 01:00:00 to 20-JAN-12 01:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in YAKIMA VALLEY, WASHINGTON
From 19-JAN-12 06:00:00 to 19-JAN-12 17:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Winter Storm in LOWER COLUMBIA BASIN, WASHINGTON
From 19-JAN-12 04:00:00 to 19-JAN-12 18:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement