Looking at the first table in the “snowfall over 30 inches” column, the February 1969 storm had an area 4.5 times larger than the March 1993 storm (16,192 vs. Well, those totals are all very impressive, but how did the “100-Hour Snowstorm” get a higher RSI score than the “Storm of the Century”? The tables below, which contain RSI scores as well as area and population information for the top 5 storms, give us the answer. Hence this storm is sometimes known as the “100-Hour Snowstorm of February 1969.” One-two punch: area and population Most of the accumulating snow in Massachusetts, New Hampshire, and Maine fell on the four days from 24 through 27 February. The primary reason for the high snowfall totals was that the storm causing all of this havoc was very slow moving, allowing snow to accumulate to these record and near-record amounts. The map shows the widespread area of snowfall in excess of 30.” Pinkham Notch had 77,” Boston 26.3,” Portland, ME, 26.9,” and Concord, NH had 28.0” of snowfall. That contributed to the February 1969 monthly total of 172.8 inches (over 14 feet), which is still their monthly record. Washington had over 4 feet of snow: 49.3 inches, which is still the one-day record. ![]() ![]() Washington in New Hampshire had over 8 feet of snow during the storm. Normally, snowfall in this country is measured in inches. The 1969 storm has some impressive snowfall totals. Map by NOAA, based on data provided by Mike Squires, NCEI. Snowfall amounts for the "100-Hour Snowstorm of 1969, which put down more than 30 inches of snow across a large part of the Northeast. It is obvious that there is a wide range of population density across the six regions where RSI is calculated. The population density in the 6 eastern regions used by the RSI is shown in the map below. So, for example, in the Northeast RSI uses thresholds of 4”, 10”, 20”, and 30.” In the Southeast the thresholds are 2”, 5”, 10”, and 15.” That way, the index takes into consideration that different parts of the country have different expectations of what is considered heavy snow. The RSI value for a specific region is based on snowfall and population information from within that region. By including population, we are taking into account how the event affected people’s lives. Scientists at NCEI and Rutgers University developed RSI which is based on the area of snowfall accumulation, the amount of snowfall, and-critically-population. There are many plausible ways one could measure societal impacts from a storm, so when it comes to rankings, the most important thing is that you come up with a reasonable method and then use it consistently. For example, a small but poorly forecast storm that strikes at rush hour has much more impact than a large well-forecast storm that strikes during a weekend. The impacts of a storm are often complicated and hard to quantify. Because of the many and varied ways snowstorms disrupt people’s lives, this is a difficult challenge. NOAA’s National Centers for Environmental Information (NCEI) has received numerous requests to provide an index that objectively ranks snowstorms within different regions of the country. To answer that question, we need to give a brief description of the RSI and how it ranks snowstorms. No way! How can that be? Trying to be objective about snow Yet when we look at the ranking of all historical Northeast snowstorms, the “Storm of the Century” only finishes in second place. Using our Regional Snowfall Index (RSI), the March 12-15, 1993, event had a raw score of 22.12, making it a Category 5 storm. ![]() Snowfall amounts for the "Storm of the Century," which walloped the East Coast between March 12-15, 1993.
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