The flood watch will remain in effect until 10 p.m. Friday.
National Weather Service observation stations showed that more than 2 inches of rain fell in parts of Lake County on Thursday.
Heavy rain fell late Thursday night in areas including the Northshore.
Another inch and a half of rain could fall through Sunday night, the forecast said, and still more rain is predicted through next weekend.
Windy conditions also are in the forecast through Sunday, with gusts of up to 30 miles per hour.
Daytime conditions this week see temperatures topping out in the low 50s, with nighttime temperatures into the high 30s.
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