As if on schedule, heavy rain began falling across Nassau and Suffolk on Thursday night, with more forecast through Friday morning, along with possible flooding and thunderstorms.
Between one and two inches of rain is expected, with more possible in some places. It had been forecast to begin sometime around 10 p.m.
By 10:30 p.m., satellite radar showed a thick band of rain stretching from one side of Long Island to nearly the other, slowly moving northeast across Nassau into Suffolk. Heavy rain, thunderstorms and gusts as high as 38 mph are forecast through the overnight, with a "marginal risk" of "strong to severe" thunderstorms moving through northern Suffolk.
The National Weather Service issued a flood advisory at 10:34 p.m. that will continue through 1:30 a.m. Friday for poor drainage areas in Nassau and western Suffolk. The weather service earlier issued a flash flood watch for Nassau and other points west through 8 a.m. Friday.
Flight delays were reported at Kennedy and La Guardia airports, according to both airports Twitter feeds at about 11 p.m. Thursday.
The storms could bring potentially damaging winds, the weather service said. Late Wednesday, PSEG Long Island's online outage map was reporting 13 outages affecting 212 customers.
An isolated tornado is also possible, forecasters said.
There is also a high risk of rip currents on the South Shore through Friday night, the weather service said.
Showers will clear out for delightful weekend weather, courtesy of a rain-clearing high pressure system that should also deliver a pleasant Monday, before the rain may return on Tuesday and clear off by Wednesday.
With Joan Gralla and Keldy Ortiz