Polar vortex bringing cold and snow to Northeast this weekend

The polar vortex will be paying the eastern U.S. an extremely rare May visit this weekend. Over 100 record low temperatures are in jeopardy, with a freak snowstorm — from a bomb cyclone, no less — also likely for the Northeast.

The polar vortex is a massive whirlwind of frigid air that typically circulates around the Arctic Circle. It tends to sink down into the U.S. a few times each winter. But this past winter it did not — instead the vortex was unusually strong and stationary, keeping cold air locked far north. 

Now, in May of all times, the cold core will swing down from Canada, bringing historic cold to the eastern U.S. from Friday night through Sunday. So, if you already put your winter clothes away for the season, you may want to fetch a sweater and coat for the weekend.

Freeze warnings and frost advisories have already been issued for the Midwest, Great Lakes and Ohio Valley, with more sure to follow into the Northeast. Sub-freezing temperatures are possible as far south as Tennessee and the hills of western North Carolina.

Fortunately, this time of year the polar vortex is not nearly as frigid because the strong spring sun has had time to moderate the air mass. So instead of temperatures below zero, we will experience we will experience 20s and 30s.

Still, this is a major concern for some farmers and home gardeners whose plants are already in bloom. If manageable, cover sensitive plants or take them inside to avoid the frost.

Many all-time record low temperatures for the month of May will be challenged. The current record lows, just to name a few, include: Pittsburgh, 26 degrees Fahrenheit; Indianapolis, 28; Louisville, 31; Boston, 31; Nashville, 34; New York City, 32; and Washington, D.C., 33. All of these records may well be approached, tied or broken on Saturday morning.

To add insult to injury, an intense storm will develop near New York City Friday night, moving up through New England on Saturday. The storm may develop into a bomb cyclone as it moves up through the Gulf of Maine, bringing 40-60 mph wind gusts over the Northeast. 

A bomb cyclone is defined as a storm in which the barometric pressure drops 24 millibars in 24 hours. This storm may very well meet that criteria.

While the exact track of the storm is not set in stone, it does appear a swath of accumulating snow is likely for parts of the Northeast from the Poconos, Catskills and Berkshires into Vermont, New Hampshire and Maine. 

Totals will range from a couple of inches in the Poconos to perhaps a foot in Maine. Along with the bombing storm, winds will gust 40-60 mph on Saturday. While snow is not unheard of in New England in May, this looks to be a once-in-a-generation event for some areas, and a few all-time record snow totals for May are possible.

In northern New England the wet snow, combined with gusty winds, may be enough to weigh down power lines and cause some sporadic power outages.

While accumulating snow is likely to miss the big cities, snow showers do seem plausible for New York City and Boston, with a coating of wet snow not out of the question. The largest May snowfall on record in New York City is just a trace, and the record in Boston is 0.9 inches. It’s conceivable these records may be matched.

With gusty winds and low temperatures forecast to be in the 20s and 30s across the Northeast, wind chills in the morning will fall deep into the teens for interior sections, and in the 20s for the big cities of Washington, D.C., Philadelphia, New York City and Boston. Wind chills will stay in the 30s most of the day.

It will turn briefly milder later Sunday and Monday, but another record-breaking cold shot will follow for the East on Tuesday.

This article has been updated to correct a temperature forecast.