Wildfire in Tacoma Area, Washington

Anomalous upper level high pressure combined with surface low pressure near the WA Coast and high pressure east of the WA Cascades led to the favorable set up for wildfires across the area. With the development of strong Cascade gap winds from the east, the Sumner Grade fire was ignited as strong winds downed trees onto power lines. The fire burned 800 acres before becoming contained. The fire causes structural damage, school closings, power outages, and evacuations.

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.