Frequency Distributions of Heavy Snowfall from Snowstorms in the United States

The frequency distributions and record heaviest snowfalls from snowstorms across the nation are defined. Data for 1948–2001 from 204 first-order weather stations identified major snowstorms in the United States, and these storm values were analyzed to determine the 5- and $10\text{-}\text{year}$ return interval values, plus the record highest value at each station. These values, which are important in design and operational issues relating to heavy snow, have been used to develop nationwide patterns of these extreme events. A latitudinal distribution of low (south) to high values (north) exists in the central United States, but the mountain ranges of the west and east have higher extreme values associated with higher elevations. Maximum snowfalls exceed $140\mathrm{cm}$ in the highest elevation locales in the Cascade Mountains. The Great Lakes also enhance storm snowfall frequencies by 20–50% on their downwind sides.