Snowstorm traffic

Nor’easters are coastal storms that typically bring heavy snow and gusty winds to interior regions of the mid-Atlantic and Northeast. They can cause severe economic, transportation and human disruption and, in some cases, disastrous coastal flooding.

The snowstorm approaching the region Wednesday qualifies as a nor’easter, according to the definition used by government forecasters and private weather services like AccuWeather.com and Weather.com, the website of the Weather Channel.

The National Weather Service describes a nor’easter as a storm along the U.S. East Coast with winds typically from the northeast. Typically, these are winter snowstorms, though they can develop at any time of the year. But they are encountered most frequently from October through March.

The word “nor’easter” usually conjures up images of streets blanketed in heaps of snow and power lines defeated by intense winds.

But, according to meteorologist Rich Otto of the National Weather Service’s Weather Prediction Center, “it’s sort of a loose term; there’s no strict definition.”

Impacts include heavy snow, typically a foot or more, but depending on temperatures, ice storm effects can include freezing rain and sleet. Wind speeds in a nor’easter can reach hurricane force, though gale force winds of 40 to 75 mph are typical.

Along the coast, rough seas and, occasionally, coastal flooding, are a given. Inland, blowing and drifting snow is common. Power blackouts caused by fallen trees and utility lines also are frequent in New England.

Well-known nor’easters include the notorious Blizzard of 1888, the “Ash Wednesday” storm of March 1962, the New England Blizzard of February 1978, the March 1993 “Superstorm” and the coastal snowstorms of January and February 2015.

The March 1993 storm, also dubbed the “Storm of the Century,” produced as much as 4 feet of snow in some areas.

In the past, nor’easters have been responsible for billions of dollars in damage, severe economic, transportation and human disruption, and in some cases, disastrous coastal flooding, the government forecast service states. Damage from the worst storms can exceed a billion dollars.

Nor’easters usually develop between Georgia and New Jersey, within 100 miles east or west of the East Coast. These storms progress generally northeastward and typically attain maximum intensity near New England, usually off Cape Cod and the Islands, and then move into the Maritime Provinces of Canada, most often Nova Scotia and Newfoundland.

Although interior New England and upstate New York often see either fringe or direct impacts from nor’easters, the densely populated region between Washington D.C., Philadelphia, New York and Boston, also known as the “I-95 Corridor,” is especially impacted.

The U.S. East Coast provides an ideal breeding ground for nor’easters. During winter, the polar jet stream transports cold Arctic air southward across the plains of Canada and the U.S., then eastward toward the Atlantic Ocean where warm air from the Gulf of Mexico and the Atlantic tries to move northward.

The warm waters of the Gulf Stream help keep the coastal waters relatively mild during the winter, which in turn helps warm the cold winter air over the water. This difference in temperature between the warm air over the water and cold Arctic air over the land is the fuel that feeds nor’easters, sometimes referred to as winter hurricanes.

There’s another kind of nor’easter, too.

The nor’easter cocktail is a mix of bourbon, maple syrup, ginger beer and lime juice.

Sources: National Weather Service at www.weather.gov/safety and The New York Times.