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Long Island forecast: Unsettled, chilly weather through mid-May

Heavy rain soaks pedestrians in Jericho on Friday,

Heavy rain soaks pedestrians in Jericho on Friday, May 5, 2017. Credit: Newsday / J. Conrad Williams Jr.

Long Island could be seeing a stretch of unsettled, chilly conditions through the middle of the month, as a jet stream pattern, common in spring, has settled in, literally, forecasters say. Some erratic weather, such as the deluge Friday in New York City, could also be in the picture.

Indeed, the line of rain that sat over the city and that brought heavy rain to parts of the Island, is part of a pattern in which “systems stay stagnant,” said Tim Morrin, National Weather Service meteorologist in Upton.

While the core of the jet stream, a narrow strip of fast-moving air that helps guide weather systems, keeps roaring along at the upper levels of the atmosphere, areas at its edges can stop or slow down, which is what was seen on Friday, Morrin said.

At this time of year, especially, with “an extreme contrast in air masses,” as areas to the south start warming, the jet stream can bend, said Dave Bowers, a senior meteorologist with AccuWeather. Instead of flowing mostly from west to east around four or more miles up, it’s “spending as much time going north and south,” he said.

Morrin described it as “an amplified roller coaster pattern.”

Add to that the stalling element and it’s like driving along a highway at 70 mph and having the car in front put on the breaks. In the jet stream’s case, we end up with “an atmospheric traffic jam,” Bowers said.

The moisture that ended up wreaking some havoc in New York City and areas of Long Island was accompanying the jet stream, which first dove from Canada’s Northwest Territories down to the Gulf of Mexico, then bouncing back up along the East Coast, bringing that gulf moisture with it, Bowers said.

On Friday Central Park registered 3 inches of rain, the weather service said, with Plainview seeing 2.27 inches; Wantagh, 1.66; and Orient, 0.92.

Flash flooding was reported at 2:11 p.m. in Franklin Square by a trained spotter, who described local streets as “nearly impassable,” the weather service said in a storm report.

Weather conditions caused flight delays at Kennedy and LaGuardia airports, the Port Authority said in an alert Friday.

Suffolk County police reported a handful of weather-related incidents, including street flooding on New York Avenue in Huntington, where at least one motorist whose car was disabled needed assistance. There also were reports of a downed tree in Huntington and wires down in Central Islip.

There were no reported injuries, a Suffolk police spokeswoman reported shortly before 3 p.m.

In Nassau, state officials reported a tree down on the Meadowbrook Parkway that temporarily blocked one southbound lane.

Nassau police reported no major weather-related traffic incidents.

More rain may be on the way with showers in the picture for Saturday and Sunday.

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