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.

Wildfire in TACOMA AREA, WASHINGTON
From 07-SEP-20 00:00:00 to 19-SEP-20 00:00:00 (PST-8)
Reported by: Social Media

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.

Wildfire in TACOMA AREA, WASHINGTON
From 07-SEP-20 00:00:00 to 13-SEP-20 00:00:00 (PST-8)
Reported by: Social Media

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.

Wildfire in CASCADES OF PIERCE AND LEWIS COUNTIES, WASHINGTON
From 07-SEP-20 00:00:00 to 15-SEP-20 00:00:00 (PST-8)
Reported by: Department of Highways

Anomalous upper level high pressure over the Northwest US combined with surface low pressure along the WA Coast and high pressure east of the WA Cascades led to favorable wildfire conditions. Strong easterly winds through the Cascade gaps led to the development of a wildfire around Enumclaw on September 8. The wildfire burned 132 acres and caused the closure of SR 410 for several weeks from Enumclaw to Greenwater WA as crews had to remove trees to continue firefighting operations. After the containment, crews had to conduct rock scaling and begin guardrail repair.

Strong Wind in HOOD CANAL AREA, WASHINGTON
From 07-SEP-20 05:00:00 to 07-SEP-20 11:00:00 (PST-8)
Magnitude: 43.00 EG
Property damage: 40.00K
Crop damage: 0.00K
Reported by: Park/Forest Service

During a period of strong easterly winds, three vessels moored on the outside breakwater at Seabeck marina in Hood Canal. The wind and wave action caused them to impact the dock. The damage included severe denting of hull and upper deck, one of the vessels was holed and took on water,  and one vessel has its engines moved about 3/4 in causing misalignment of prop shafts. All vessels had damage to the Starboard side.

Strong Wind in SEATTLE AND VICINITY, WASHINGTON
From 07-SEP-20 14:00:00 to 08-SEP-20 12:00:00 (PST-8)
Magnitude: 30.00 ES
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Utility Company

Strong easterly winds resulted in widespread power outages in the Seattle metro area as tree limbs fell onto power lines. The town of Burien reported tree branches falling on wires, resulting in a power outage affecting 5300 customers. Seattle City Light reported a power outage near Beacon Hill affecting 5000 customers.
Several brush fires were also reported during this period of strong wind.

Strong Wind in TACOMA AREA, WASHINGTON
From 07-SEP-20 14:00:00 to 08-SEP-20 12:00:00 (PST-8)
Magnitude: 30.00 ES
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Utility Company

Strong easterly winds resulted in an estimated 2500 customers without power by the early morning hours of September 8. During the afternoon of the 7th, tree limbs fell on power lines in the Fife and Browns Point areas, with around 5000 customers losing power.
Several brush fires were reported during this period of strong winds: a brush fire closed SR 512 at I-5, a brush fire closed S 56th St, a brush fire closed the I-5 offramp to Martin Way in Olympia, a brush fire blocked several lanes of I-5 near Federal Way.