Long Island weather: Nassau flood watch begins at noon; heavy rain, thunderstorms expected

A flood watch was set to begin at noon Thursday in Nassau County and will continue through 11 p.m., with an increased chance of heavy showers and thunderstorms, according to the National Weather Service.

Atmospheric conditions could produce rains heavy enough in a short duration to produce flooding, especially in urban areas or those with poor drainage, the weather service said.

"The concern [for Nassau] is locally heavy rainfall, where maybe one or two storms could briefly produce rainfall rates up to two inches per hour," weather service meteorologist David Stark told Newsday Wednesday evening. "It's kind of the story we've seen off and on all summer."

Areas west of New York City are forecast to see heavier rainfall, Stark added. And "it's possible," he added, "that parts of Suffolk will not see any rain."

Early Thursday, the weather service issued a special alert updating its forecast, saying the threat for severe thunderstorms has increased somewhat, mainly north and west of New York City.

For the areas under the watch, which includes New York City, the lower Hudson Valley and northeastern New Jersey, 1 to 2 inches of rain with locally higher amounts are possible, with scattered instances of flash flooding.

Forecasters say severe thunderstorms accompanied by damaging winds are also a threat Thursday. Wind gusts in excess of 58 mph could damage trees and power lines.

For anyone considering turning Thursday into a beach day, the weather service warned that "life-threatening rip currents are likely for all people entering the surf zone" across the entire South Shore.

High temperatures Thursday will reach the low 80s in Nassau and Suffolk. Evening lows will drop into the upper 60s.

Check back for updates on this developing story.