Saturday, August 16, 2014

Twisp vs Winthrop

On this gorgeous, clear day with no smoke, let's take a look at the differences between two air quality monitors located less than 9 miles apart in the same Methow Valley.  The blue graphs indicate 1-hr average concentrations of PM2.5 while the red data points are 24-hr averages. Note that while the 24-hr values trended rather similar for the two sites (expected as they are spatially close) the peak 1-hr values differed greatly!

Why would this be? As you can see in the graphic below (orange ovals depict drainage valleys below the fires), smoke from the Upper Falls Creek Fire drains directly into Winthrop prior to reaching Twisp. So when that fire has been active, Winthrop will experience higher smoke concentrations.

On the other hand, the Little Bridge Creek Fire drains directly into Twisp, bypassing Winthop almost completely! So if one fire is more active than the other, the two communities, while close, may experience greatly different air quality.  And that is the what's been going on...  Note that today, both areas are fine places to be!

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