Flash flood alerts issued for LI

A flash flood watch will remain in effect for Nassau County through Friday night, the National Weather Service said Thursday.

In Suffolk, the watch extends until late Thursday, the agency said. Radar showed "flash flooding from thunderstorms over the warned area," the agency said.

"Any thunderstorms that develop in this environment will be capable of producing torrential rain, resulting in areas of flash flooding," the weather service said. New York City, the lower Hudson Valley and northeast New Jersey may also see flooding, the agency said.

Storms also were possible Friday morning, with fog before 10 a.m., the weather service said. Friday was to be mostly cloudy with a high near 81.

Saturday was to be partly sunny, with a high near 80. There will be a chance of showers and thunderstorms after noon and areas of fog before 9 a.m.

Sunday is expected to be mostly sunny with a high near 82, forecasters said.

Because of the heavy rainfall, Suffolk County Health Commissioner James L. Tomarken issued an advisory Thursday against bathing at 22 beaches. Heavy rain can cause high bacteria levels in water at the beaches, Tomarken said.

To find out which beaches are on the list, call the county Bathing Beach hotline at 631-852-5822, contact the Health Department's Office of Ecology at 631-852-5760 or visit suffolkcountyny.gov/health and click on the Beach Advisories and Closures link.

Affected beaches are located in areas that are heavily affected by stormwater runoff from the surrounding watersheds and tributaries. These beaches are not flushed by the tides because they are enclosed.

The Health Department recommends that people do not swim until at least 24 hours after the rain has stopped.