Thunderstorm Wind — Washington, Oregon

2009-06-04 · near Sherwood, Washington, Oregon

Event narrative

Outside of Chapters Books and Coffee in Newberg, a tree with estimated diameter 10 to 12 inches was snapped in half. Also, numerous spotter reports just to the north and with similar conditions were reported.

Wider weather episode

A fairly vigorous upper level low pressure system had been blocked offshore and was finally allowed to progress onshore on June 4th. An upper level disturbance rotated around upper level low pressure system, enhancing divergence aloft and turning upper level flow easterly across much of western Oregon. This overall pattern resulted in enhanced vertical wind shear for the Willamette Valley, with southerly winds near the surface backing to easterly flow aloft. The June 4, 2009 was a significant thunderstorm outbreak by Northwestern Oregon standards, with several areas taking damage from strong thunderstorm wind gusts, minor urban area flooding, and rotation in a few storms resulted in one weak tornado.

View location on OpenStreetMap → (45.3005, -122.9725)

Source: NOAA Storm Events Database, event_id 183910. Narrative written by the NWS forecast office that issued the report.