Wednesday, August 28, 2019

Eh? Whats that smoke over the Puget Sound and Yakima?

Around 11AM yesterday the satellites started detecting a large cloud of smoke from a hotspot in the Wenatchee National Forest in Yakima county, just east of Highway 410. This was from a 300-acre prescribed burn authorized by DNR. Smoke was buoyant and lofted over the Cascades courtesy of strong east winds. Here's what the satellite picture looked like at 5PM yesterday.

The fire was smoldering this morning and a further 230 acres were authorized for burning at the same location today. A little bit of the smoke that drifted west appears to have mixed to the surface this morning, with several Puget Sound area monitors recording Moderate air for a few hours. The latest smoke models show this dissipating by afternoon today. However the residual smoke could exacerbate the potential for ozone (smog) formation in the east slopes of the King/ Pierce County Cascades today, so air quality due to the combination of fine particles and ozone is likely to stay in the Moderate to Unhealthy for Sensitive Groups through late this evening. On-shore airflow overnight is likely to restore Good air quality to most of western WA by Thursday.

Since smoke models assume that fires continue to emit all day & night, they're predicting that the Yakima valley will see some smoke impacts today & tomorrow. Given such assumptions, it is hard to determine the amounts of smoke that will actually reach populated areas. Needless to say some smoke is projected to drain into the valley so nearby communities should brace for compromised air over the next day or so.

Models are also showing that smoke from the Cow Fire in Oregon (see above) is likely to brush the far southeastern part of the state by Thursday evening into Friday as the wind shifts. Amount of smoke is unknown at this time.

All this bears watching. We will post an update and a long weekend outlook on Thursday.

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