I'm still looking for the source(s) of this smoke. GOES satellite imagery has been inconclusive and I'm still waiting on a MODIS image. There are, however, 10 current large wildfire incidents in Utah, Nevada, and Idaho.
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| Source: USFS/NIFC |
These range in size from 700 to 40,000 acres, the largest being the Big Hill Fire (#4). With a weak trough passage late yesterday, we had a brief period overnight with northwesterly flow that could have brought in smoke from the Big Hill and other fires in southern Idaho.
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| NAM surface wind analysis at 0600 UTC 16 Aug 2011. |
Given their size, the southern Idaho fires seem to be the most likely potential source for such dense, widespread smoke. The West Sahara Fire in Utah (#10) is only 700 acres and the Stockade Fire (#9) in eastern Nevada is only 390 acres.
The impact of this smoke on air quality is quite evident in PM2.5 observations from Salt Lake City. In particular, we climbed dramatically after midnight to a peak of over 30 ug/m3.
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| Source: Utah Division of Air Quality |
I agree, that is pretty clearly where our smoke came from. The southwestern part of Idaho is quite dry in the summer and typically has some very large range fires in August. All it takes is a weak cold frontal passage with fire activity in the Snake River Basin, and we end usually up with a lot of the smoke. I can recall at least several major smoke episodes here in late summer that were tied directly to fires in that area.
ReplyDeleteWas supposed to read *usually end up with*.. apparently I am dyslexic or something.
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