We've entered the peak time of year for major Northeast winter storms

The Northeast Snowfall Impact Scale is used to rate the impact of Northeast snowstorms on a 1-to-5 scale

Winter storms can dump heavy snow across the Northeast at any time during the colder months, but there is a distinct peak in the frequency of these major snowstorms beginning in the back half of January.

According to data from NOAA's National Centers for Environmental Information, nearly three-quarters of all Northeast snowstorms rated Category 3 or higher on the Northeast Snowfall Impact Scale, or NESIS, between 1956 and 2021 occurred from late January through February.

There were 35 such storms during that 65-year period, of which 26 happened between Jan. 16 and Feb. 29. An even more pronounced peak was observed in the first 14 days of February, comprising one dozen of the Category 3 or higher winter storms.

WINTER STORMS AREN'T NAMED, BUT THEY ARE RATED ON A 1-TO-5 SCALE

Most recently, a snowstorm that hit the Northeast from Jan. 30 to Feb. 3, 2021, received a Category 3 NESIS rating. Central Park recorded 17.4 inches of snow, and much of the New York City tri-state area picked up more than a foot.

The NESIS scale, developed in 2004 by National Weather Service meteorologist Paul Kocin and former NWS director Dr. Louis Uccellini, is used to rank the impact of Northeast snowstorms based on snowfall amounts, the area affected by the storm and the population living in its path.

A widespread, heavy-snow event over a highly populated area such as the Boston-to-Washington Interstate 95 corridor will yield a high ranking on the NESIS scale. A Category 1 winter storm is considered "notable," while a Category 5 snowstorm is classified as "extreme."

WHAT MAKES A STORM A NOR'EASTER?

For many cities along the Interstate 95 corridor, the late-January-through-February peak in major Northeast winter storms is highly evident in their average snowfall during that time period.

New York City, Philadelphia and Washington each typically receive more of their seasonal snow between Jan. 16 and Feb. 29 than over the rest of the winter combined. 

HOW ONE POINT ON A MAP CAN MAKE OR BREAK A NORTHEAST SNOWSTORM FORECAST

The average snowfall in Central Park over the entire winter is 29.8 inches, but in an average year, more than half of that falls from late January through February. This holds true in Philly and the nation's capital as well.

There have been only two Category 5 winter storms on the NESIS scale since 1956. The first was the "Storm of the Century" in March 1993, and that was followed by the "Blizzard of '96" just three years later in January 1996.

You can read more about those two storms, as well as five other memorable Northeast snowstorms, at this link.

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