Flash flood watch, heavy rain expected on Long Island Sunday morning

Heavy rain will pour across Long Island Sunday, bringing isolated thunderstorms and potential flooding to the region.

"We're looking at a soaker through the midday," Newsday TV meteorologist Geoff Bansen said Saturday evening.

Pockets of heavy rain will push across the Island starting early Sunday and last into the afternoon, according to the National Weather Service. Generally, 1½ to 3 inches of rain are expected, though the weather service cautioned that stronger storms could produce higher rainfall totals of 5 to 7 inches in some areas.

Bansen said it's difficult to predict what areas of Long Island will experience the heaviest rainfall.

"They're going to be localized, and they're virtually impossible to pin down," Bansen said. "If you have a basement or a yard that floods easily during heavy rain events, take the evening to prepare and shore that up."

On Long Island, a flood watch is in effect from 5 a.m. to 2 p.m. Sunday.

There are "marginal" to "slight" risks of flash flooding during that time frame. Flash floods are less likely on the East End, according to the NWS bulletin issued at 6 p.m. Saturday.

NWS meteorologist Jay Engle said a flood watch does not mean flooding will happen.

"A flood watch is just the potential, like the ingredients are there for some flooding to occur," he said. "When we issue a flood watch, we look for like a 50% chance and then when we issue warnings it's like 80%."

Rumbles of thunder are also possible, though storms are not expected to be severe. Bansen said the "most torrential rain" will come from the thunderstorms.

Temperatures are expected to remain in the upper 70s on Sunday. The rainfall is expected to ease after 2 p.m. and conditions will improve.

"The sun will be coming out across the Island from west to east" after 2 p.m., Bansen said.

Monday will be mostly cloudy through mid-morning with a high temperature in the mid-70s. Engle said there's a "slight chance" of showers but that any potential rainfall Monday is "not a big deal."

The forecast calls for largely sunny conditions and temperatures in the low-to-mid 70s throughout the workweek, Engle said.