Oregon Smoke over Washington. Ends Monday.

 The visible satellite image this morning shows a plume of smoke over Washington, smoke that mainly originated over eastern Oregon.

The effects of the smoke were pretty obvious over western Washington, with an attenuated, red sun rising to the east this morning:

The smoke is thick enough that the intensity of solar radiation has decreased noticeably (see measurements at Seattle below for the last three days below).   That means we will be cooler today as a result. 

Air quality is good on the coast, moderate over the western lowlands and the Columbia Basis, and poor over sections of eastern Oregon

The laser ceilometers run by the Puget Sound Clean Air Agency clearly show the smoke moving in aloft.  Here is an example from the instrument at  Beacon Hill, Seattle. The time is on the x-axis (increasing to the right) and the y-axis is height in meters (3000 meters is about 10,000 ft).  Quite a deep layer of smoke is moving through overhead.

.   

Nearly all the smoke is coming from extensive fires in grass, bushes, and scattered trees in eastern Oregon (see current fire areas below).  Numerous lightning and human-ignited fires have occurred in the rangeland of eastern Oregon, with other fires over the southern Oregon Cascades.   The extensive, lush flammable invasive grasses (like Cheatgrass) are a real problem.

For most of the summer, the smoke from the fires did not influence western Oregon or Washington because winds generally move from west to east in our region.

But during the last few days, easterly winds have prevailed, associated with a thermal trough extending into western Oregon.     To illustrate, here is the forecast weather map at 850 hPa (about 5000 ft) this morning.  The solid lines are like pressure and you can see the wind symbols.  Easterly winds over northern Oregon and southern Washington.

Below are  the air motions at the same level (5000 ft) ....something called streamlines.   You can see why the eastern Oregon smoke is approaching us.

Fortunately, the situation is going to change during the next 36-48 hours.

Here are the streamlines showing airflow at 5 PM Sunday.  The wind direction has radically changed...now out of the Northwest.  That will blow the smoke away.

To show the improved smoke situation, let me display the smoke forecast (total in a vertical column) from the highly skillful HRRR smoke prediction model.  

This morning at 8 AM. Lots of smoke.

Tomorrow morning at 7AM, still smoky.

But by 5 AM Monday morning, the switch to northwesterly flow was doing its magic, with western Washington nearly clear of smoke.   Tuesday will be even better.

Relief is on the way!