Thursday, September 27, 2012

Air Time: Air quality 'hazardous' again in Wenatchee, Cashmere

Air Quality Program, Air monitoring update

Here's the air quality conditions and weather forecast for Thursday, Sept. 27 ...
Wildfire smoke has poured back into the Wenatchee and Cashmere areas, plunging air quality there back into the “hazardous” category.

Both communities have been hammered by smoke carried by winds from area wildfires. Some afternoon clearing occurs when the inversion breaks and upvalley winds kick in. On Wednesday (Sept. 26), Entiat and Pateros showed air quality as “unhealthy for sensitive groups,” while air was “unhealthy” in Leavenworth. Twisp, Winthrop and Cle Elum (all “moderate”) showed the opposite trend, with increasing fine particle pollution levels recorded when winds during the day pushed smoke toward air quality monitors.

Monitors showed air quality was “unhealthy” in Trout Lake and Ellensburg, “unhealthy for sensitive groups” in Yakima and Toppenish, and “moderate” in White Swan and Goldendale. All of those communities saw an increase in fine particle pollution when the inversion broke. But they experienced some partial clearing later on Wednesday.

Omak and Quincy air monitors are reading “good,” but fine particle monitors elsewhere east of the Cascades are reporting compromised air quality today (Thursday, Sept. 27). Columbia Basin monitoring sites show little change since Wednesday, with a mixture of “moderate” air to “unhealthy for sensitive groups.”

Light east winds have started in Eastern Washington and could still bring some smoke from Idaho wildfires to the Palouse before Friday night. With strong nighttime inversions, above normal daytime temperatures and light winds, the largest smoke impacts are expected near the fires while the Columbia Basin will continue to experience a steady state in which as much smoke enters as leaves.

In general, expect some smoke impacts in the morning and nighttime, with some afternoon clearing in most places. The light east winds could push some smoke farther up the Cascade foothills during the day.

Winds are expected to pick up on Friday evening; models suggest that gradual clearing in most areas is expected to continue through Saturday evening before calm conditions return.

The National Weather Service issued an Air Quality Alert for all of Eastern Washington:

Gov. Chris Gregoire has banned all outdoor burning in Eastern Washington through midnight Sunday. The ban does not apply to tribal lands where the U.S. Environmental Protection Agency has jurisdiction.

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