Entering Yosemite on September 17, smoke veiled the Yosemite high country, but by late afternoon it has partially cleared, and that resulted in the images posted a few days ago, from Tenaya Canyon.
On September 18, a monstrous black smoke plume enveloped the Eastern Sierra from Lone Pine to Lee Vining, so thick that it completely obscured the entire range from view. AQI went from near zero (crystal clear) to extremely unhealthy in a matter of a few hours, inducing burning eyes and a headache as just some of the obvious problems.
Below, I drove south towards Big Pine and thence into the Inyo range near Eureke Dunes in order to try to escape the rapidly advancing smoke plume which sent AQI from crustal clear to extremely unhealthy within an hour.
I drove towards Eureka Dunes to escape it, and camped overnight with clean air, but by morning the yuck surrounded me and the entire White Mountains area and I spent the next day and night sealed up in my van with nowhere to escape the smoke.
Below, by early morning there was no escape even east of the White Mountains into northern Death Valley.
On September 19, a northwest front blew away the thick choking smoke from the Eastern Sierra, resulting in the cleanest air in years that I can recall—stunningly crisp views to even far-away peaks, totally free of haze. That lasted all day and part of September 20, when smoke breached the Tuolumne Meadows area.
By the morning of September 21, another massive smoke plume enveloped the Eastern Sierra. Peaks began disappearing from view and the acrid choking smoke was out of the question. So I drove east into Nevada for clean air, which as I write this is still clean, but half the sky eastwards to the Sierra is a massive grayish-white mess. Supposedly it might clear out tomorrow.
Below, the temporarily stratified smoke plume rapidly would fill all the air within a few hours with dense choking smoke. I could see it fill Glacier Canyon (near Mt Dana) and other nearby areas, so I left in haste.