This happened during a fucking El Nino and those are the death of snow usually. El Ninos bring death ridges and/or split flow hell which is usually an 🤮🤮🤮 pattern spelling the end of winter before it even starts. Some El Nino's like 2002 will have a mini cold spell at the beginning to fool you like October 2002 or 2019-2020.
My lowest low for Oregon is still October's 2019's low of 21F I've yet to exceed lower then that. I wonder if I ever will?
Here's a special article about the 69 snowstorm: http://special.registerguard.com/csp/cms/sites/web/news/5675242-35/story.csp
The Big Snow It came without warning and left the city under a record-setting blanket of white
I do not mean it like you think.
As soon as humans observed that, say, a volcanic eruption could change the weather due to the smoke it emits, and noticed that they could light huge fires and also make a fuck ton of smoke, they realized that weather modification is possible.
This was likely in the neolithic era. Since then, technology has increased effect and efficiency significantly.