The Smoke Outlook for the Next Week

Air quality today is far better over the region today that last week, but some smoke is present and will stay present.

Here is the latest surface particulate map from the wonderful  Washington State smoke website : http://wasmoke.blogspot.com/.  Most of the sites are green (good air quality)....but there are problem spots.   Because of the Maple Fire on the Olympic Peninsula and persistent wildfires on northern Vancouver Island, some smoke is getting into western Washington.  That is why a few central Puget Sound sites are reporting moderate levels (but on the low level of moderate).  And the persistent fires on the northeast slopes of the Cascades are producing moderate to unhealthy values there.

This pattern is going to stay in place for the next week, based on on the latest model runs.  Forecasts are for the maintenance of a ridge of high pressure offshore and generally northwesterly flow--no heat wave--but the Vancouver Island smoke can waft into western Washington.  To illustrate, here is the forecast map for upper level (500 hPa) flow at 5 PM Saturday.  No heat wave.  Generally onshore flow.

The entrance of clouds into our region has revealed a problem with the NOAA/NWS HRRR smoke model I have shown in previous blogs.   It bases its fire location on satellite data (like VIRS) and when clouds occur, the fires are not well defined.  The Canadian smoke model seems to do better.

I suspect that we have seen the worst of the smoke for this season here in western Washington, so it is useful to view a trace of air quality at Seattle to get some perspective (see below for June 28th through today).   Particulate levels (PM2.5) were relatively low through approximately August 10th (although there was a small spike on July 4th).    We had two weeks of smoke, with some peaking into the very unhealthy range (above roughly 120).  Now we have settled down into low-moderate level (roughly 15-20)-- some smoke, but far down from the previous peaks.

It is interesting to compare this against recent years.   For 2017, there was a two week period in early August, that was bad, but not quite as bad as this year.

And 2015, a much warmer year that this one-- a summer similar to what we expect during the 2070s, had far less smoke that this year.

Clearly, there are subtleties to the connection between smoke and weather, something I will explore in a future blog.

Finally, for those living in Seattle, a new smoke measurement site has been put on top of my building at the UW, thanks to the US Forest Service (and particularly thanks to Susan O'Neil of the FS that supervised its installation).  This link will get you there (see graph at 8 AM Wednesday below)

from Cliff Mass Weather and Climate Blog https://ift.tt/2PiwmEq