This paper describes a collaborative effort between NOAA's National Climatic Data Center and Rutgers University to develop regional snowfall indices on an operational basis. In 2004, Kocin and Uccellini developed the Northeast Snowfall Impact Scale (NESIS) to characterize snowstorms in the northeast. The index is based on the spatial extent of the storm, the amount of snowfall, and the juxtaposition of population and snowfall. Including population information ties the index to societal impacts. The NESIS was calculated for approximately 70 historical northeast snowstorms. In 2005, NCDC began calculating NESIS scores operationally for large snowstorms affecting the northeast.

The goal of the current project is to develop NESIS-like indices for other regions of the country. The indices will be calculated in a similar fashion to NESIS, but our experience has led us to propose a change in the methodology. Different techniques are examined and a final algorithm is presented. The new indices require region specific parameters and thresholds for the calculations. The paper discusses the assumptions and applicability of regional snowfall indices and how they may help explain the societal impacts of snowstorms.