How Often Does Visibility Go to Zero?


 The air quality situation remains very poor this morning, with the murk heightened by the mixture of fog and low stratus over portions of western Washington.  Red (unhealthy) air over Puget Sound, very unhealthy (purple) air over the coast and eastern Cascade slopes), and hazardous (dark purple) air over the Willamette Valley and southeast Washington.  

The values in the Willamette Valley are frightening—many with an AQI over 400– and the combination with fog has resulted in extraordinarily low visibilities.   Local weather enthusiast, Dr. Peter Benda, brought Eugene, Oregon to my attention, where visibility dropped to ZERO miles (see below).  You don’t see that very often!

There will be only slight improvement during the day today, but tonight the models are emphatic that onshore flow will provide some relief.  The NOAA HRRR-smoke model shows poor air quality over Puget Sound at 11 AM today (see below) and worse over the Willamette Valley and eastern WA and Oregon.

But by 9 PM tonight, the promised relief is on the way, with cleaner air pushing in from the west.  

And by 11 AM on Monday, serious relief will be at hand:

I should say that one encouraging sign is the thinning of the smoke over western Washington that is evident in the latest visible satellite image, with the densest smoke being blown to the east (see below).  You can event see the fog layer.


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