The phenomenon occurs when specific atmospheric conditions align perfectly. In this case, a combination of factors contributed to the formation of the cloud waterfall : ...

The 270-foot cascading Snoqualmie Falls in the mountains outside Seattle as seen in 2009. The falls were roaring this week after an atmospheric river.

Here's a before and after shot of the waterfall, taken on Oct. 22 and again on Monday. Before and after views of Yosemite Falls spanning Friday (top) to Monday (bottom) in Yosemite National Park, CA.