Dense Fog — Northern Blue Mountains, Oregon

2023-09-21 · Northern Blue Mountains, Oregon

Event narrative

Around 12:30pm PDT, Oregon State Patrol responded to an multi-vehicle incident involving nearly 30 vehicles near mile post 227 on I-84, with two confirmed semi-trucks having caught fire, several motorists reporting minor injuries, and at least one report of a series injury. Multiple Oregon DOT weather stations between mileposts 219 and 229 reported visibilities a quarter mile or less at times before and after the traffic incident. Due to the incident, I-84 was closed both directions between Pendleton and La Grande for over 8 hours according to media.

Wider weather episode

A cloud layer forming from upslope processes along the Blue Mountain Foothills resulted in ground fog developing between Cabbage Hill and Poverty Flats in the Northern Blue mountains, or between at least mile posts 219 and 229 along I-84. Reductions in visibilities lead to a significant multi-vehicle accident that closed the freeway down for approximately 8 hours.

Source: NOAA Storm Events Database, event_id 1142233. Narrative written by the NWS forecast office that issued the report.