Wildfire — Tacoma Area, Washington

2020-09-07 to 2020-09-13 · Tacoma Area, Washington

Event narrative

Anomalous upper level high pressure over the Northwest US in combination with surface low pressure along the WA Coast and high pressure east of the WA Cascades led to the development of favorable wildfire conditions. This particular set up led to the development of strong east winds through the Cascades gaps amidst dry antecedent conditions. In Graham, WA several brushfires were initially reported as windy conditions knocked over power lines. These brushfires later combined to form a larger wildfire that led to evacuations of local residents, and eventually structural damage to local homes and buildings. The fire burned 275 acres before becoming contained on Sept 13.

Wider weather episode

Around Labor Day and through the first full week of September, an anomalous upper level ridge set up over the Northwest US, with a thermal trough developing along the Pacific Northwest Coast with high pressure east of the Cascades at the surface. This setup was responsible for the development of strong easterly winds and high wildfire/fire spread threat. The generation of numerous wildfires then led to a prolonged period of poor air quality.

Source: NOAA Storm Events Database, event_id 922441. Narrative written by the NWS forecast office that issued the report.