This Scientific Equation Shows NYC Blizzards Are Worse Than Midwestern Ones

​New York City and the southern part of New York state is currently under a blizzard warning, issued by the National Weather Service, as up to two feet of snow heads to the area over the next 24 hours. Mayor Bill de Blasio warne​d New Yorkers to "prepare for something worse than we have seen before," and Governor Andrew M. Cuomo forewarned of multiple transportation closures by the time the storm is at full force.

At times like this, New Yorkers can face mockery from those ​who hail from snowier climes. Midwesterners and, I hate to admit it, my fellow Canadians ​occasionally like to act as though the storms that wallop Manhattan are little more than an average January squall back home.

But a look at the data on blizzards across the country shows the storms that have paralyzed Gotham are just as bad as any that shut down other areas of the country. In fact, given the dense population of New York, a scientific scale developed by the National Oceanic and Atmospheric Administration would categorize the storms as much worse.

Taking a look at snowfall alone, NYC is no stranger to hefty hits of the white stuff. The biggest was in 20​06, when the city was dumped with 26.9 inches of snow in just 16 hours. That's pretty close to the worst Mich​igan has ever seen (28 inches) and much higher than 23 inches in Chicago (the most single daily s​nowfall). Even Iowa, the state that invented the term bli​zzard, barely beat NYC with its record of 27 inches.

In Canada, there have been some higher accumulations. One of the worst in Toronto's history was in 1999, when the city was coated in 46 inc​hes of snow during a two-week storm. But the nearly four feet of snow crippled the city—the mayor had to call in the army to help dig them out—while New York's 2006 blizzard was dealt with in a matter of days as 2,500 city workers ran 12-hour shifts to clear the streets. The subways were still running, though delayed, and nobody was injured or killed.

Other Canadian cities have seen more snow—the most in a single day was 47 inches—but it's hardly a common occurre​nce.

Of course, snowfall isn't the only gauge for how mild or wicked a winter storm is. There's temperature, wind, ice, snow drifts, and how well a city is equipped to deal with the storm (a bit of freezing ​rain in Florida can sometimes cause more havoc than heavy snowfall in New York). There's also the number of people it affects, which led the NOAA's National Climatic Data Center to create a sc​ale to scientifically calculate how severe a winter storm is: the Regional Snowfall Index. They take into account the size of the area affected, the amount of snowfall, and the population, run it through an equation based on the region of the country where the storm hit and then rank the storms from 1 to 5.

When you take into account population in this way, a smaller amount of snow can have a bigger impact in a population-dense area like Manhattan, said Michael Squires, a meteorologist at the NCDC who developed the scale.

The NCDC has been tinkering with the calculation for a few years, but it's now confident in its ability to quantify the severity of storms past and present. The center published a peer-reviewed paper on the Regional Snowfall Index in the upcoming issue of the Bulletin of the American Meteorological Society.

Squires, who co-authored the paper, told me there are factors that are left out of their equation, like temperature and windspeed, that can affect how severe a storm seems. He said the equation also doesn't account for the time of day—a storm at midnight on Saturday is more manageable than one at 5 PM on Tuesday—and ho​w well the storm has been forecast. Still, he said it's a useful tool for gauging the severity of winter storms and comparing them to the storms of the past. And if you're still unconvinced of the legitimacy of New York's blizzards, Squires had one truism of winter weather to share:

"You could live in an area that gets a lot of snow but it's not a big storm in terms of area and that might not have a large RSI score at all," he told me.

"But if you get 15 inches of snow, that's a lot of snow. It doesn't matter where you live."