The first accumulating snowfall of the season is expected this weekend as a potentially “significant winter storm” could bring heavy snow, high winds and coastal flooding to Long Island, according to a hazardous weather outlook issued by the National Weather Service.
Forecasters are watching the development of two low pressure systems that they expect to combine off the coast and move northeast, passing close to or east of the 40/70 benchmark Saturday night.
The “benchmark” — 40N 70W — is typically associated with heavy snow makers for Long Island; winter storms that pass over or near it usually produce significant snowfall across the region.
It’s still too early to predict the exact track of the storm or snowfall totals, forecasters say, but “there is potential for six inches or more.”
If the coastal low travels up the coast on a track west of the benchmark,it will likely bring in warmer temperatures off the warm ocean waters.
“It was an anomalously warm December and so far January is above normal well, which means warmer than normal ocean temperatures,” according to the NWS forecast discussion.
A surface low is expected to form in the midwest Thursday and head northeast, where there will be a polar high pressure system in place, according to the NWS forecast. The polar high will provide the cold air needed for the potential winter storm. A secondary low will then develop over the Southeast near the Gulf Stream, providing moisture that will allow the storm to strengthen as it heads up the East Coast Friday night, forecasters say. The low then passes close to or east of the 40/70 benchmark by Saturday night.
Precipitation will begin as early as Friday afternoon, from southwest to northeast, according to the weather service.