The variables measured on the scale include area, amount of snowfall, and the number of people living in the path of the storm. These numbers are calculated into a raw data number ranging from "1" for an insignificant fall to over "10" for a massive snowstorm. Based on these raw numbers, the storm is placed into one of the five categories. The largest NESIS values result from storms producing heavy snowfall over large areas that include major metropolitan areas. Only three historical storms—the 1993 Storm of the Century, the North American blizzard of 1996, and the January 2016 United States blizzard—are in the Category 5, with a NESIS value higher than 10.