A heavy batch of rain moved into the region Tuesday evening, with some parts of New London County getting more than 6 inches of rainfall, and heavier rain predicted for overnight.

As of 10 p.m., Groton had picked up 1½ inch of rain at the airport, while Willimantic had 4.5 inches and Lebanon reported 6.79 inches, the highest in New London County, according to Ryan Hanrahan, chief meteorologist at NBC Connecticut. While it rained during the day on Tuesday, the heaviest rain began falling about 7 p.m.

In the eastern part of the state, the National Weather Service issued a flash flood warning for the following areas until 11:15 p.m. Tuesday: Jewett City, Norwich, Colchester, East Hampton, Salem, Waterford, East Lyme, Ledyard, Griswold, East Haddam, Lebanon, Preston, Lisbon, Sprague and Bozrah. People in flood-prone areas along streams and creeks were urged to take precautions to protect their lives and property and were advised to move to higher ground.

"Turn around, don't drown when encountering flooded roads," the weather service warned. "Most flood deaths occur in vehicles." It also warned drivers to be especially cautious at night, when it is harder to see and recognize flooding dangers.

Meteorologists were monitoring late Tuesday the Yantic River in Norwich to figure out how high it would likely rise, as smaller brooks and rivers flooded and ran into the river.

"We're watching the gauge on the river to figure out how high it's going to get," Hanrahan said. "That could cause some problems in Norwich later tonight or tomorrow morning."

Incidents were reported in Franklin and Lebanon of roads undermined and cars trapped in flood waters, as many rivers and brooks started to overflow their banks, Hanrahan said.

There was a mudslide in East Haddam near the Goodspeed Opera House, according to state police. It occurred about 8:30 p.m. and prompted the shutdown of Route 149 in the area.

Utility Eversource's website showed scattered power outages all across Connecticut Tuesday night.

In the southwestern part of the state earlier Tuesday, downpours caused flooding around Norwalk, The Hour reported there, closing several roadways, including Interstate 95. Retail areas flooded, causing several vehicles to get stuck. Police Lt. Terry Blake told The Hour that numerous smaller secondary roads were impassable.

Ana Lara of East Norwalk was driving when her Honda Pilot got stuck in a flooded section of road. “I was driving and the visibility was not good,” she told The Hour. “I took a right and then I was in the middle of the water and my car wasn’t working.” Lara said even though she was stuck, two other cars tried to pass, and they also got stuck.

Police and firefighters were dashing around to numerous incidents just like that one and were advising people to stay off the roads because flooding was occurring “everywhere.” Norwalk police also advised people not to not attempt to drive through the puddles, tweeting “turn around, don’t drown,” on Twitter.

Parts of Interstate 95 were closed, including near Exit 16. Metro-North service also was impacted, with the 4:13 p.m. train from South Norwalk to Danbury delayed because of high water conditions, The Hour reported. 

The hazardous weather might not be over yet. The Storm Prediction Center placed New London County under a slight risk for severe thunderstorms on Wednesday, saying the storms could bring strong, damaging winds.

The heaviest rain was predicted to move into New London County overnight but the flooding was expected to recede by Wednesday morning, Hanrahan said. A couple of storms were expected for Wednesday morning but it should clear out for the day on Wednesday, with the possibility of a thunderstorm at night, he said.

k.drelich@theday.com