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The Northeast Snowfall Impact Scale (NESIS)

National Oceanic and Atmospheric Administration

National Climatic Data Center


24-28 December 2010
24-28 December 2010

Overview

While the Fujita and Saffir-Simpson Scales characterize tornadoes and hurricanes respectively, there is no widely used scale to classify snowstorms. The Northeast Snowfall Impact Scale (NESIS) developed by Paul Kocin and Louis Uccellini of the National Weather Service (Kocin and Uccellini, 2004) characterizes and ranks high-impact Northeast snowstorms. These storms have large areas of 10 inch snowfall accumulations and greater. NESIS has five categories: Extreme, Crippling, Major, Significant, and Notable. The index differs from other meteorological indices in that it uses population information in addition to meteorological measurements. Thus NESIS gives an indication of a storm's societal impacts. This scale was developed because of the impact Northeast snowstorms can have on the rest of the country in terms of transportation and economic impact.

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).

NESIS Calculations

Table 1: NESIS categories, their corresponding NESIS values, and a descriptive adjective:

CategoryNESIS ValueDescription
11—2.499Notable
22.5—3.99Significant
34—5.99Major
46—9.99Crippling
510.0+Extreme

Table 2: Ranks 41 high-impact snowstorms that affected the Northeast urban corridor.

Click on hyperlinked dates for snowfall map. Sort by NESIS rank or storm date.

Rank Dates NESIS Category Description
1 12-14 March 1993 13.20 5 Extreme
2 6-8 January 1996 11.78 5 Extreme
3 2-5 March 1960 8.77 4 Crippling
4 15-18 February 2003 7.50 4 Crippling
5 2-5 February 1961 7.06 4 Crippling
6 11-14 January 1964 6.91 4 Crippling
7 21-24 January 2005 6.80 4 Crippling
8 19-21 January 1978 6.53 4 Crippling
9 25-28 December 1969 6.29 4 Crippling
11 14-17 February 1958 6.25 4 Crippling
10 10-12 February 1983 6.25 4 Crippling
12 29-31 January 1966 5.93 3 Major
13 5-7 February 1978 5.78 3 Major
14 12-15 February 2007 5.63 3 Major
15 23-28 February 2010 5.46 3 Major
16 21-23 January 1987 5.40 3 Major
17 8-12 February 1994 5.39 3 Major
18 24-28 December 2010 (preliminary) 4.92 3 Major
20 18-20 February 1972 4.77 3 Major
19 17-19 February 1979 4.77 3 Major
21 11-13 December 1960 4.53 3 Major
22 4-7 February 2010 4.38 3 Major
23 22-28 February 1969 4.29 3 Major
25 9-11 February 2010 4.10 3 Major
24 12-13 February 2006 4.10 3 Major
26 18-21 January 1961 4.04 3 Major
27 18-21 December 2009 3.99 2 Significant
28 23-25 December 1966 3.81 2 Significant
30 18-21 March 1958 3.51 2 Significant
29 8-10 February 1969 3.51 2 Significant
31 5-8 February 1967 3.50 2 Significant
32 6-7 April 1982 3.35 2 Significant
33 15-18 March 2007 2.54 2 Significant
34 24-26 January 2000 2.52 2 Significant
35 30-31 December 2000 2.37 1 Notable
36 31 March - 1 April 1997 2.29 1 Notable
37 18-19 March 1956 1.87 1 Notable
38 1-3 March 2009 1.59 1 Notable
39 22-23 February 1987 1.46 1 Notable
40 2-4 February 1995 1.43 1 Notable
41 25-26 January 1987 1.19 1 Notable

References:

Kocin, P. J. and L. W. Uccellini, 2004: A Snowfall Impact Scale Derived From Northeast Storm Snowfall Distributions. Bull. Amer. Meteor. Soc., 85, 177-194

Squires, M. F. and J. H. Lawrimore, 2006: Development of an Operational Snowfall Impact Scale. 22nd IIPS, Atlanta, GA.


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