Thursday, July 27, 2017

Northern WA and Lewis Clark Valley smoke forecast

Several areas in north central and north eastern Washington saw periods of Moderate air over the last 2 days. While smoke from the Diamond Creek fire north of Mazama has been hitting the Methow valley,  the Noisy Creek and Bissell fires caused smoke in the northeast. Clarkston got hit by smoke from the Craig Mountain Complex fire as the nighttime inversion broke this morning.

East winds are unlikely in the coming days, and since the Craig Mountain Complex fire is now almost fully contained, mostly Good air quality is likely in the Lewis- Clark valley.

If the Diamond Creek fire continues to produce smoke, winds are very likely to keep the Methow Valley somewhat smoky. Here's a snapshot of what we call 'ensemble forward trajectories': it shows how air masses at different heights are likely to travel forward from a certain location. Starting at 11PM tonight, air upto about 1500 feet is likely to drain via the Methow valley over the next 12 hours, bringing smoke from the fire down to ground level. The "ensemble" part refers to how different forecast models characterize the same scenario. The colored lines represent the means of all such models for each release height.

Good consensus that the Methow lies downwind of the fire tonight. Expect Moderate air at night and mostly Good as the day progresses. If smoke is released above 1500 ft, it is possible that some could circle around and mix down when the temperature inversion breaks in the morning. This could lead to Moderate air around Omak and Okanogan, with gradual improvement during the day.

Weekend and beyond are shaping up to be hot with light winds. Here's a snapshot of an ultra-cool animation of temperatures and winds at 2500 ft on Sunday afternoon (not much different to Saturday).

Smoke impacts over the weekend will depend on fire activity. If the status quo persists, the above forecast should be good through Monday.

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