Heavy rain, which swept across Long Island, was expected to exit the East End area by late afternoon, forecasters said.

A flood advisory that had been in effect through 2:45 p.m. for eastern Nassau and much of Suffolk counties, indicated that some areas could see up to 1 1⁄2 inches of rain an hour, the National Weather Service said. That meant runoff from poor drainage areas could cause flooding of roads, highways, underpasses and other low lying areas.

Trained spotters measured 1.61 inches of rain in Massapequa and 1.45 inches in Wantagh, with the weather service office in Upton seeing .97 of an inch, said Jay Engle, weather service meteorologist.

Rain should be pushing off the Twin Forks by around 4 to 4:40 p.m., he said.

LaGuardia Airport was seeing arrival delays at midafternoon averaging around 1 3⁄4 hours, and delays were close to an hour for Kennedy arrivals, according to the Federal Aviation Administration website. Some departures were also being impacted, the FAA said.

Temperatures Friday were registering in the upper 60s and low 70s, the weather service said.

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The overnight hours Friday night into Saturday morning bring a chance of showers and thunderstorms, the weather service said. Still, there was some uncertainty as to how much the system might hold together, Engle said.

Saturday afternoon could bring partly sunny skies, with the day’s high temperature heading up to the mid-80s, the weather service said.

Sunday will be sunny with a high in the low 80s, the weather service said.

“We should have a pretty decent weekend,” said Rich Hoffman, News 12 Long Island meteorologist.