This is the 10879th most frequent Russian word.
выпал
"Выпал" means "fell out" or "dropped out."
Here, 'выпал' describes the falling of snow, emphasizing the resultant state of the city covered in snow.
Снег выпал на город за ночь.
The snow fell on the city overnight.
In this context, 'выпал' is used to denote a person inadvertently falling out of a window.
Он выпал из окна и испугал прохожих.
He fell out of the window, terrifying the passersby.
The word 'выпал' metaphorically signifies the sudden appearance of something, akin to it 'falling out' onto the screen.