BC wildfire smoke affecting northern WA

Smoke from a fire near Princeton, BC has been affecting parts of Okanogan, Ferry and Stevens counties over the last few mornings. This afternoon's satellite picture shows smoke from the (circled) fire.

The fine particle pollution monitor in Omak bears out the evidence most prominently. Notice how levels spiked over the last 3 mornings.

This happens when (1) northwest flows overnight transport smoke into the area via the Okan(a)ogan river valley, followed by (2) the inversion layer breaking up as the morning sun heats the ground, and (3) smoke aloft mixes to the surface. But daytime winds switch to the southwest and help dissipate smoke- albeit slowly. 

Expect another round of the same smoke behavior in the north central counties from Sunday to Tuesday. Periods of Moderate and USG air are likely during the overnight and morning hours. Unhealthy air in communities such as Oroville and Tonasket cannot be ruled out.

And finally, be prepared for more fire concerns on Sunday, followed by a progressively hotter work week.