High Wind in Grand Ronde Valley, Oregon

A combination of a strong thermal gradient between the lower Treasure Valley and the Columbia Basin and significant momentum transfer of strong winds aloft created localized areas of significant damaging winds in the foothills of the Blue Mountains and Grande Ronde Valley. Interstate 84 was closed for several hours between Pendleton and La Grande after a tractor trailer was blown over coming off the Blue Mountains toward Pendleton. A mesonet station in close proximity to this blow over reported a gust of 78 knots (90 mph) around the time of the accident. Portions of Highway 11 between Pendleton and Milton-Freewater were also closed briefly as a precaution with crosswind gusts estimated at 61 knots (70 mph). Winds decreased rapidly away from the foot of the mountains.