Northeast Snowfall Impact Scale: Ranking winter storms

The 1983 snowstorm ranked #10 on record with a NESIS of 4 out of 5.

Scales already exist to categorize severe weather making it easier to document and explain to the public.  The (Enhanced) Fujita Scale classifies tornadoes, while the Saffir-Simpson realtes to hurricanes.  In 2004, the snow gurus Paul Kocin (formerly on The Weather Channel), and Louis Uccellini developed a system for documenting snow storms with widespread impacts.  The Northeast Snowfall Impact Scale (NESIS) have large regions with 10 inches of snow or more and are broken down by five categories: Extreme, Crippling, Major, Significant, and Notable. This does include not only the storm itself, but how widespread the impact.  So large storms for Baltimore did not necessarily impact the rest of the northeast.  Since New York City's population is much higher than ours, a smaller storm could have a wider impact for travel and commerce.

See the slide show below for the maps of the top 20 storms.   Click here for the top 21-37

According to NOAA:

NESIS scores are a function of the area affected by the snowstorm, the amount of snow, and the number of people living in the path of the storm. The diagram below illustrates how NESIS values are calculated within a geographical information system (GIS). The aerial distribution of snowfall and population information are combined in an equation that calculates a NESIS score which varies from around one for smaller storms to over ten for extreme storms. The raw score is then converted into one of the five NESIS categories. The largest NESIS values result from storms producing heavy snowfall over large areas that include major metropolitan centers. For details on how NESIS scores are calculated at the National Climatic Data Center, see Squires and Lawrimore (2006).

For more info: