Updated at 5:40 p.m. and 4:10 p.m. Sunday

A flash flood watch is in effect for Howard County and much of Maryland until 10 p.m. Sunday, according to the National Weather Service (NWS).

During a flash flood watch, creeks and streams may rise above their banks onto roadways.

At 5 p.m., a line of storms from Glenwood to Elkridge was moving north at 25 mph, said the NWS. 

Four inches of rain had fallen through parts of Maryland as of 3:08 p.m. Sunday, the NWS reported, and certain areas could see 2 to 3 more inches before the day's end.

By 2 p.m. Sunday, Roosevelt Boulevard in Elkridge had flooded, the Maryland Department of Transportation reported via its Twitter feed. Officials had cleared the street near Meadowridge Road for traffic by 2:30 p.m.

Citizens should exercise caution near highways, underpasses, streams and other areas that may flood. Drivers should use caution and turn around if they see roadways covered by water, said officials with the NWS.

The Federal Aviation Administration advised that flights out of BWI were delayed Sunday afternoon as a result of the weather.