Smoke from California May Have Arrived in the Mountains

Many people over the past few days have wondered if some of our pollution is from the California fires and up until today, the answer was no.

Smoke from California fires is NOT affecting pollution in Salt Lake. Our pollution is from local sources. We have met the enemy and it is us. Modis imagery below shows smoke from CA fires blowing offshore. pic.twitter.com/CflS1nTKZm

— Jim Steenburgh (@ProfessorPowder) December 9, 2017

If you live in the lowlands along the Wasatch Front, the answer to that question is probably still no.  We are in a soup of locally produced pollution that is quite isolated from changes aloft.

However, in the mountains, the answer might be yes.

I went up to Alta this morning for a quick tour and workout, and was quite surprised to see some dense haze in the canyon.  This haze was especially apparent looking down canyon from the upper Albion lot.

After our climb, the view toward Heber showed some dense haze that appeared to be thicker aloft than right near the surface in the valley.

What was quite strange was how spotty and variable the haze was.  At times, the air looked quite clear in one area, but hazy in another.  One thing that was clear is that there didn't seem to be any spread of pollution from the valley to high elevations, as suggested by the photo below.

Thus, I don't think the mountain haze is from the valley pollution.  Providing further evidence of this, the morning sounding at KSLC showed an incredibly strong inversion, with the temperature within the inversion increasing more than 10ºC.  My experience with such strong inversions is that the air is typically quite clean once you are above them.

I wonder if instead some smoke from the California fires has finally crested the ridge and dropped down into northern Utah. Over the past several days, that smoke has been pushed offshore and at times northward along the Pacific Coast.  Monday's Modis image, for example, shows the smoke offshore, along the coast, and wrapping northward off the Northwest Coast.

Modis Image 11 December 2017.  Source: NASA

Yesterday, however, that smoke had spread inland across much of Washington and Oregon, and possibly across northern Idaho.

Modis Image 11 December 2017.  Source: NASA

 Thus, it is possible that the northwest flow has finally transported that smoke into our area.  As I write this, we haven't gotten a Modis overpass yet, but one will be coming soon and it should be interesting to see what it shows.

Note that this does not mean that the smoke is contributing to our problems in the valley.  The smoke is likely elevated and the inversion that prevents the pollution from entering the valley, also limits the spread of smoke aloft into the cold pool.  The smoke instead simply adds to the misery by reducing the clarity in the mountains.