Flash flood warning in effect for parts of Cook and DuPage counties

The National Weather Service issued a flash flood warning for parts of Cook and DuPage counties until 1:30 p.m. Sunday as rain falls at nearly one inch per hour through Chicago.

Doppler radar showed thunderstorms producing heavy rain of one to two inches across east central Cook County and eastern DuPage County in northeastern Illinois at about 7:30 a.m., weather officials said. They said they expect another one to two inches of rain, and that flash flooding is “ongoing or expected to begin shortly.”

Officials warned of flash flooding in Chicago, Cicero, Bolingbrook, Oak Lawn, the O’Hare International Airport, Austin, South Lawndale and more. They urge people to avoid walking or driving through flood water and to move immediately to higher ground during a flash flood.

“Turn around, don’t drown when encountering flooded roads. Most flood deaths occur in vehicles,” officials cautioned.

The NWS also warned that soaking rain with embedded lightning and pockets of torrential rainfall will continue throughout the Chicago metro area Sunday morning. They recommend that people avoid flooded paths and roadways, and move indoors if they hear thunder.

A special marine warning, including Lake Michigan from Winthrop Harbor to Wilmette Harbor, is in effect until 11 a.m. Officials spotted severe thunderstorms capable of producing waterspouts, which can overturn boats and create locally hazardous seas. People should seek safe harbor, officials said.

Early-morning conditions at the Chicago Midway International Airport are light rain at 60 degrees.

rjohnson@chicagotribune.com