They have the equipment to plow the field before the game starts. The field has to be ready 1.5 hours before kick off so teams can go out and do warm ups.
And I googled it as well and found 16" fell during the Colts game.
https://www.skysports.com/nfl/news/12040/12749482/buffalo-braced-for-historic-snowfall-but-bills-game-against-cleveland-browns-expected-to-still-go-ahead#:~:text=Latest NFL standings&text=The Bills were involved in,game 13-7 in overtime.
https://en.wikipedia.org/wiki/Snow_Bowl_(2017)