Operational ranking of U.S. snowfall events

Regional operational US snowfall indices are being developed through a collaborative effort between NOAA's National Climatic Data Center and Rutgers University. Indices are based on the spatial extent of a storm, the amount of snowfall, and the juxtaposition of population and snowfall. They are being developed and applied within the nine climate regions employed by NCDC, as well as on a nationwide scale. They should prove valuable in assessing the impacts of snow events on public safety, business and commerce. This work extends the previous efforts over the Northeast by Kocin and Uccellini, Squires and Lawrimore and our team. Here we discuss the translation of raw regional indices into 5 categorical values. The breakpoints for the categories are designated such that the top category will include only a few storms, perhaps the top 2-5%. The other categories will become progressively larger and will also be based on percentiles. Examples for storms of various magnitudes will demonstrate the efficacy of the system on regional and national scales.