A system bringing heavy rain will linger over Long Island through Saturday morning, bringing scattered showers, stretches of downpours and potential flooding, the National Weather Service said.
"The bulk of the precipitation will be late Friday afternoon and night, and into late morning Saturday," said Lauren Nash, a meteorologist at the service's Upton office.
Nash said the forecast Thursday calls for scattered showers as a warm front approaches and then lifts.
For Thursday afternoon and into the evening, there's a 30 to 40 percent chance of "pop up" showers -- light and "very scattered," Nash said.
Minor coastal flooding is likely Thursday night as southeasterly winds coincide with astronomical tides along Nassau's and western Suffolk's north and south shores, according to a coastal flood statement. Tides could run from half a foot to a foot and a half above astronomical levels, with the higher levels along the South Shore, the statement said.
An incoming cold front extending from the Great Lakes to the Gulf Coast states slowly passes through Friday night and moves out of the area by Saturday.
That means rain, up to about 2 inches, for most of Long Island into Saturday morning. A flash flood watch is in effect from Friday afternoon to late Friday night for Nassau County's north and south shores, the weather service said, with heaviest rainfall expected to coincide with high tide. One to 2 inches of rain is expected, possibly up to 3 inches in localized spots.
Also, patchy fog is expected during the early morning and late evening hours, from Thursday to Saturday, the service said.
The weather was causing arrival delays at LaGuardia Airport of an average of about 90 minutes, and more than an hour at Kennedy Airport, according to the Federal Aviation Administration.
Some departures were also being delayed, according to the FAA, which advised travelers to check with their airlines.
In its hazardous weather outlook, the service also warned of minor coastal flooding, and flooding of roads and low-lying areas because of heavy rain.
The arrival of a warm front sent temperatures Thursday to the low- to mid-70s. Temperatures will be around 70 Friday, when "a dousing of rain" is expected to start in the midafternoon and last through midmorning Saturday, said Tim Morrin, also a meteorologist with the Upton office.
Look for steady rain, at times heavy, with an occasional thunderstorm, he said.
Saturday and Sunday look to be partly to mostly sunny with highs near 70.
But don't look for "a sustained transition to fair weather," Morrin said, as "the atmosphere is a little unsettled" and there's a chance of more showers on Monday.