Snowfall map of the Great Blizzard of 1978, the highest-ranking storm on the Regional Snowfall Index, outlining the six regions assessed with the scale.

The Regional Snowfall Index (RSI) is a system used by NOAA to assess the societal impact of winter storms in the United States. The system is a replacement for the Northeast Snowfall Impact Scale (NESIS) system. Since its initiation, the NCDC has retroactively assigned RSI values to over 500 historical storms since 1900.

Storms are ranked from category zero ("Nuisance") to five ("Extreme") on the scale. The impact of the storms is assessed in six different regions of the United States: Northeast, Northern Rockies & Plains, Ohio Valley, South, Southeast, and Upper Midwest.[1] A category five Extreme ranking is indicated by a numerical score of 18 or higher on the scale.

Out of the over 500 historical storms assessed since 1900, only 26 storms have been given a category five ranking. The highest ranking storm on the list is the Great Blizzard of 1978, which scored a value of 39.07. The most recent storm to receive a category five ranking is the January 2016 United States blizzard, which scored a value of 20.14. The following list orders the storms chronologically.[1][2][3]

List of Category 5 events

Year Date Max. RSI Region Ref(s)
1920 April 14–18 20.84 Northern Rockies and Plains [4]
1921 February 17–21 31.89 South [4]
1922 January 25–29 18.53 Southeast [4]
1927 February 26 – March 2 24.42 Southeast [4]
1927 April 4–10 34.20 Northern Rockies and Plains [4]
1929 December 18–23 21.13 South [4]
1940 January 20–23 18.14 Southeast [4]
1943 January 18–25 21.14 Northern Rockies and Plains [4]
1950 November 11–21 34.69 Ohio Valley [4]
1966 February 27 – March 5 20.38 Northern Rockies and Plains [4]
1967 January 24–28 18.13 Ohio Valley [4]
1969 February 21–27 34.03 Northeast [4]
1971 February 18–23 19.36 South [4]
1978 January 22–27 39.07 Upper Midwest, Ohio Valley [4]
1978 February 5–7 18.42 Northeast [4]
1984 April 24–27 25.95 Northern Rockies and Plains [4]
1985 February 6–14 27.06 Upper Midwest [4]
1985 November 27 – December 1 22.19 Upper Midwest [4]
1988 January 4–8 22.64 South [4]
1991 October 30 – November 3 30.18 Upper Midwest [4]
1993 March 11–14 24.63 Northeast, Ohio Valley, Southeast [4]
1993 November 20–28 22.00 Northern Rockies and Plains [4]
1996 January 5–8 26.37 Northeast, Southeast [4]
2009 December 21–28 19.62 Northern Rockies and Plains [4]
2011 January 31 – February 2 21.99 Ohio Valley [4]
2016 January 19 – January 29 20.14 Northeast [4]

Listed by month

See also

References

  1. ^ a b "Regional Snowfall Index (RSI)". NOAA: National Centers for Environmental Information. Retrieved 16 February 2016.
  2. ^ "Regional Snowfall Index and Societal Impacts". Retrieved 2014-11-18.
  3. ^ "NOAA Product Highlight: Regional Snowfall Index". Archived from the original on 2014-11-29. Retrieved 2014-11-18.
  4. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa Squires, Michael; Lawrinmore, Jay; Heim, Richard; Robinson, David; Gerbush, Mathieu; Estilow, Thomas. "The Regional Snowfall Index" (PDF). American Meteorological Society. Retrieved 22 July 2017.
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