Development of an operational northeast snowfall impact scale

While the Fujita and Saffir-Simpson Scales characterize tornadoes and hurricanes, for decades there has been no widely used scale to classify snowstorms. The Northeast Snowfall Impact Scale (NESIS) was developed by Paul Kocin and Louis Uccellini to characterize and rank the severity of snowstorms based on snowfall amount and population of the affected area. In a cooperative effort to create an operational version of the NESIS that can be used in NOAA's climate monitoring activities, NOAA's National Climatic Data Center developed a reproducible GIS-based method for calculating the NESIS during future snowfall seasons. Some of the GIS computational issues encountered while calculating NESIS include quality control, development of a robust population density grid, and selection of an appropriate spatial interpolation scheme. This paper describes the different methodologies used to calculate NESIS, examines the uncertainty inherent in the estimated value, and recommends procedures for calculating NESIS operationally beginning with the 2005-06 winter season.