If the people you’re talking to understand “snowing to beat hell,” no reason you can’t say it. But there isn’t a local go-to that’s quite the equivalent of a “raining cats and dogs.” “Dumping” is a pretty close snow equivalent of “pouring” or “pouring rain.” I’ve always lived in snowy climates (here and in Canada) and mostly just use phrases like “snowing hard,” “coming down fast,” “piling up out there.”