The National Weather Service extended a flash flood warning for parts of Cook and Lake counties until 5 p.m. Sunday as heavy rain fell throughout the Chicago area.

       Doppler radar and rain gauges showed thunderstorms producing 3 to 6 inches of rain across southeastern Cook County in northeastern Illinois and northwestern Lake County in northwestern Indiana at about 2:15 p.m., weather officials said. They said they expect another 1 to 2 inches of rain, and that flash flooding is “ongoing or expected to begin shortly.”

       Officials warned of flash flooding on the Far South Side of Chicago, Hammond, Dolton, Tinley Park, Oak Forest and more. Ongoing flooding was being reported in Calumet City, officials said, filling streets and leaving some vehicles stranded.

       Vehicles sit in water at the corner of Saginaw and Stewart Avenues in Calumet City, Sept. 17, 2023, after heavy rain drenched the area (Eileen T. Meslar/Chicago Tribune)

       They urged people to avoid walking or driving through flood water and to move immediately to higher ground during a flash flood.

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       “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 afternoon. They recommended that people avoid flooded paths and roadways, and move indoors if they hear thunder.

       Weather officials also warned of dangerous currents at Lake Michigan beaches with waves of 3 to 6 feet through Monday morning in Lake, northern Cook and central Cook counties. They said swimming conditions are life-threatening, especially for inexperienced swimmers, and advised people to stay out of the water.

       A small craft advisory, from Winthrop Harbor to Calumet Harbor, is also in effect until 7 a.m. Monday. Conditions are unsafe for inexperienced mariners, especially those operating smaller vessels, officials cautioned.

       Late-afternoon conditions at Chicago Midway International Airport were mostly cloudy at 67 degrees.

       rjohnson@chicagotribune.com

       Originally Published: Sep 17, 2023 at 9:13 am