Winter Weather — Upper Columbia Basin, Washington

2013-12-20 · Upper Columbia Basin, Washington

Event narrative

Moderate snow, slick conditions, and excessive speed was responsible for a ten car pile up along Interstate 90 seven miles east of Ritzville at 1246 PST. Eleven people were involved in the crash, four which were injured and one which died on the scene. Eight of the ten cars were totaled. Snowfall totals at the time of the accident were generally around an inch. Roughly an hour later, a car rolled over at mile post 77 along Highway 395, eighteen miles south of Ritzville. The driver of the vehicle suffered serious injuries.

Wider weather episode

A trough of low pressure had become established over the Inland Northwest by the 19th of December as a ridge of high pressure anchored over the Eastern Pacific. Meanwhile, a fetch of subtropical moisture topping the offshore ridge became aimed into the region by late on the 19th and majority of the 20th. Strong isentropic processes ahead of a stalled warm front led to a period of moderate to heavy snow across portions of Eastern Washington and Northern Idaho. Most locations east of a line from Republic to Ritzville picked up between two and four inches. Slightly heavier amounts were observed across the Palouse. Slick conditions led to numerous car accidents across the region with the worst accident occurring at mile post 229 along Interstate 90. Ten cars were involved resulting in several injuries and one fatality. The Washington State Patrol reported to over ninety collisions that afternoon across Spokane, Adams, Whitman, and Stevens Counties.

Source: NOAA Storm Events Database, event_id 481949. Narrative written by the NWS forecast office that issued the report.