Thunderstorms are expected in the Chicago and surrounding Illinois area during the day and into the evening Wednesday, according to the National Weather Service. | Graphic via NWS

The National Weather Service says gusty thunderstorms could produce downpours and damaging winds Wednesday evening in Lake and McHenry counties.

The National Weather Service (NWS) on Wednesday afternoon issued a hazardous weather outlook for Lake, McHenry, Boone, Winnebago, Cook, DuPage, Kane, Will, Ogle, Lee, DeKalb, LaSalle, Kendall, Grundy, Kankakee, Livingston, Iroquois and Ford counties.

The outlook said scattered storms will continue across the area during the afternoon.

A separate area of thunderstorms near the Mississippi River will move eastward into the area Wednesday evening through 8 p.m.

A few of the storms could possibly be strong to severe, the NWS said.

The storms may produce damaging hail and winds and frequent lightning, the outlook said.

They may also produce heavy downpours that could cause ponding on roads and parking lots.

A special marine warning is also in effect for nearshore waters on Lake Michigan from Winthrop Harbor to Calumet Harbor and for open waters from Winthrop Harbor to Michigan City.

[Suggested Article]  Man hospitalized after being wounded in reported shooting in store parking lot in Waukegan

The main hazard includes wind gusts to 40 knots. Small craft could be damaged in high winds and suddenly higher waves, the warning said.

Warm and humid conditions will continue to lead to heat index values between 95 and 100 degrees.

Lingering spotty showers are possible into Thursday morning.