This mega snowstorm is sparing major cities like Boston, NYC. Here's why

The snow was flying Monday in the nation's capital, creating traffic headaches but also gorgeous wintry scenes of the monuments coated in a white layer of fluff.

Folks may be wondering: Why isn't this winter storm roaring up the coast, also battering New York City and Boston with heavy snow and wind?

Blame large-scale weather patterns for this storm track, which National Weather Service meteorologist Zack Taylor calls "not totally unusual."

The current pattern is what meteorologists call "zonal," meaning weather systems move generally west-to-east across the country. That's what's happening with this storm, which dumped snow and ice in a nearly perfect 1,100-mile west-to-east swath from the central Plains to the Ohio Valley to the Mid-Atlantic on Sunday and Monday.

In addition to that zonal flow of air, a large storm in Atlantic Canada is also impacting our weather in the U.S., AccuWeather meteorologist Tom Kines told USA TODAY.

"A big storm in eastern Canada is deflecting storms south off the mid-Atlantic coast," he said. "Until that storm starts to move away there's no way a storm can affect New England."

Zonal vs meridional flow

According to meteorologist Jeff Haby, when "upper-level winds are parallel or nearly parallel to the lines of latitude, the wind pattern is termed zonal. When the winds cross the latitude lines at a sharp angle, the wind pattern is termed meridional."

He said storms tend to move faster (west to east) when associated with a zonal flow.

Meridional flow is often associated with stronger storms such as nor'easters. "During periods of meridional flow, surface storms tend to move slowly, often intensifying into major storm systems," according to the textbook Meteorology Today by C. Donald Ahrens.

Not a nor'easter

Monday's snowstorm will not be classified as a classic nor'easter, Taylor said, which are some of the most infamous winter storms for East Coasters.

Nor'easters are large, intense areas of low pressure that typically develop off the East Coast during the late fall, winter and early spring.

The storms are called "nor'easters" because they usually bring strong northeast winds over the East as they move north along the Atlantic Coast. Nor'easters also often bring heavy rain, heavy snow and severe coastal flooding to the big cities of the East Coast, including Boston, New York City, Philadelphia and Washington, D.C.

Many nor'easters can produce blizzard conditions for a time, especially in New England.

This article originally appeared on USA TODAY: Why this winter storm is blasting D.C. but sparing other major cities