Evaluating the February 2013 Blizzard with the Regional Snowfall Index

Feb 7-10, 2013 Regional Snowfall Index Map

A massive blizzard hit the Northeast February 9–11, 2013 bringing more than 2.5 feet of snow to some areas, which left thousands of people without power and stranded countless airline passengers. This blizzard rated 3 out of 5 on the Regional Snowfall Index (RSI) scale according to preliminary observations through 7:00 AM Sunday, February 10. (We will continue to update these statistics as more station data become available.) While the area impacted by this storm was less than many other major storms, the heaviest snowfall landed in more densely populated areas, making it a “major “storm in the RSI categories. Over 49,000 people across 192 square miles saw 30 inches of snow or more as a result of this storm.

NCDC produces the RSI for significant snowstorms that impact the eastern two-thirds of the United States. The RSI uses the area and amount of snowfall from land-based stations combined with the population in the affected area to rank snowstorm impacts on a scale from 1 to 5, similar to the Fujita scale for tornadoes or the Saffir-Simpson scale for hurricanes.

NCDC has analyzed and assigned RSI values to over 560 storms as far back as 1900, and new storms are added as they occur. This range of values allows the RSI to put the regional impacts of snowstorms into a century-scale historical perspective. The index is useful for the media, emergency managers, the public, and others who wish to compare regional impacts between different snowstorms.

The RSI and Societal Impacts Section provides the regional RSI values for particular storms as well as the area and population of snowfall for those storms. The area and population are cumulative values above thresholds specific to the snowfall climatology of each region. For example, the thresholds for the Southeast are 2, 5, 10, and 15 inches of snowfall while the thresholds for the Northeast are 4, 10, 20, and 30 inches of snowfall.