Smoke Pushes Into Washington State

Today, there was a dramatic reduction in visibility over much of Washington State as smoke from the large numbers of British Columbia wildfires surged southward.   The smoke was clearly evident in satellite imagery, such as the NASA MODIS image taken at roughly 1 PM (the red dots are fire locations).   Both eastern and western WA turned smoky.

The visible satellite imagery from the new GOES 16 satellite, also show the smoke (at 6:30 PM)

There was a rapid degradation of visibility during the morning as the smoke moved in, something apparent from the Seattle Space Needle Panocam.  Here are two images, one at 6:10AM and the other at noon.  Rainier disappeared.  The sky turned whitish and milky.

Air quality declined rapidly, something noted in the EPA AirNow graphic for the Air Quality Index (AQI).   Red and orange are the worst.

Why did the smoke move southward, while it was happy to stay in BC the last few weeks?

 Because the developing heat wave is producing lower pressure (thermal trough) over Oregon, producing a north-south pressure difference (with lower pressure to the south).  This supported northerly flow.   The forecast sea level pressure map for 2 PM shows you what I mean (solid lines are isobars, lines of constant pressure).

Tomorrow (Wed), we will have both smoke and heat (temperature peaking near 90F around Seattle).
Truly, smoke and brimstone.

from Cliff Mass Weather and Climate Blog http://ift.tt/2u29SkS