A snow storm in the United States occurs when a cold air mass meets moisture and lift, producing significant snowfall, low visibility, strong winds, and hazardous travel conditions. Snow storms vary by region, lake-effect snow in the Great Lakes, nor’easters along the East Coast, and mountain snowstorms in the Rockies. NOAA defines snowstorms based on snowfall rate, accumulation, and visibility impacts.
Official guidance is available here:
https://www.weather.gov/fgz/WinterStorms
