Buildings covered in snow at the Islip Grange in Sayville...

Buildings covered in snow at the Islip Grange in Sayville on Friday, March 10, 2017. Credit: Joseph D. Sullivan

One snowstorm down, a potential nor’easter on the horizon.

The National Weather Service’s Upton office alerted Long Islanders Friday of the “potential for a strong coastal storm producing a significant snowfall, strong winds and possible coastal flooding” Monday night into Tuesday.

Still “the only thing that we can be reasonably sure of is that there will be a coastal storm nearby,” News 12 meteorologist Bill Korbel said. “Whether it will produce heavy snow or snow changing to rain on Long Island is the question we won’t be able to answer for a couple of days.”

At this early stage there is a one in three chance for the system’s “producing warning level heavy snow, high winds, and/or moderate coastal flooding,” according to Gary Conte, weather service meteorologist in Upton.

Two possible options he outlined are:

  • For the intensifying system to stay closer to the Atlantic coast, passing over the Island and leading snow Monday night to switch to rain on Tuesday, meaning snowfall accumulations of less than 6 inches.
  • For the storm to move farther offshore, passing south and east of the Island, which could mean “heavy snow well in excess of 6 inches.”

It’s too soon to make calls as to whether this would in fact be a nor’easter, as storms tracking closer to the coast don’t necessarily bring winds from that direction, hence the term “coastal storm,” said John Murray, also a weather service meteorologist in Upton.

The picture involves “one system handing off its energy to another,” and much is riding on where that occurs, said Paul Walker, a senior meteorologist with

The first system would be moving across the Ohio Valley, en route to a rendezvous along the Eastern Seaboard with another developing system.

If that connection is made over land, or right at the shore, the enhanced system would head north, pulling warmer air from the south up on its eastern side, Walker said. For Long Island, that would mean more of a rain or rain/snow mix.

A meetup offshore and we’re talking snow, he said, with winds coming out of the east or northeast — making it a potential nor’easter.

Of course, an energy handoff well out to sea would mean a miss, which can’t be ruled out, he said, but as of Friday computer models were not showing much enthusiasm for that option.

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As for Friday’s storm, it was a record breaker — at least for March 10. The 4 inches recorded at Long Island MacArthur Airport broke the old daily record of 2 inches set in 1993, according to the weather service.

The storm arrived later than expected Friday morning, enabling schools to stay open and commuters to get to work without too much trouble.

Perhaps of more significance is the arctic air rushing in after the snow, dropping temperatures an average 15 to 20 degrees below normal Saturday through early Monday.

It’s this cold air that opens up the window for Tuesday’s possible snow.