The National Weather Service office in Upton issued a flash flood warning for Suffolk County, including the East End, on Tuesday night.
The warning is in effect until 11:15 p.m.
According to the bulletin, at approximately 9:42 p.m., National Weather Service doppler rader indicated flash flooding from thunderstorms along a line extending from nine miles north of Rocky Point to 31 miles south of Oceanside, and along a line extending from 10 miles northeast of Port Jefferson to 20 miles east of Asbury Park.
Mike Layer, NWS meteorologist, said at approximately 10:20 p.m. the line of storms was moving through central Suffolk County, had just passed Nichols Road, and was heading east.
"The line is pretty solid," Layer said. "It will rain hard pretty much everywhere" on the East End. "Lower lying roads with poor drainage areas are the places that have to worry more about the flooding," he added.
The storms are moving eastward and northeast at 35 miles per hour, Layer adde.
Officials say most flood deaths occur in automobiles. Residents are advised never to drive vehicles in areas where the water covers the roadway. Flood waters are usually deeper than they appear; just one foot of flowing water is powerful enough to sweep vehicles off the road, authorities say.
The NWS advises residents when encountering flooded roads, they should "make the smart choice" and turn away, and to "turn around; don't drown."
A flash flood warning means that flooding is imminent or occurring. Residents in the warning areas should move to higher ground immediately; residents living along streams and creeks should take immediate precautions to protect life and property. Individuals are advised not to attempt to cross swiftly flowing waters of unknown depth by foot or automobile.
NWS officials say the heavy rains are expected to begin to move out by midnight.