Canadian Smoke Followed by Cooling

 The Canadian smoke, produced by fires in the boreal forests of the sub-arctic, is above us now.

You can this tell by the slightly milky shading of the sky, or by viewing the visible satellite imagery this morning (see below).

Puget Sound Clean Air Agency (PSCAA) has a device (a ceilometer) that measures smoke aloft.  The image around noon clearly showed the most intense smoke layer around 3000 - 4000 meter above the surface, with lesser smoke below (time increases to the right)

The air quality across the region was good (green) to moderate (yellow) this afternoon, so I suspect that few are having problems with poor air quality at this point.    The situation will deteriorate tonight as the major fireworks displays get going and folks go crazy with their home displays.

Temperatures rose to the mid to upper 80s over western Washington and were only a bit warmer across the Columbia Basin.   Winds were relatively light in the Columbia Gorge, which is very helpful for restraining the Tunnel Fire.

Tomorrow and Thursday will be similar to today, but then the cooling begins on Friday.    And the changed circulation with the cooling will push the Canadian smoke to the east.

The key change is a shift from having an upper-level ridge of high pressure over the eastern Pacific for today (see plot below)  to having a trough of low pressure over the northeast Pacific something illustrated by the forecast map for Sunday at 8 PM (second map)

The predicted change should bring precipitation back to the area and particularly to British Columbia.  The forecast accumulated precipitation through Tuesday is shown below.  Rather heavy precipitation is predicted over southern BC.   This is excellent news for Northwest residents since it will both reduce the wildfire threat over BC (and we can experience some of their smoke) and put water into the Columbia.

At this point, it appears that the region should enjoy a week of near-perfect weather starting Friday, with highs staying in the 70s over western Washington, no Canadian smoke,  and a lack of lightning or strong winds that could ignite wildfires.  Probably the best weather in the nation.