A Flash Flood Watch is in effect for Thursday and Friday in Montgomery County, and Montgomery County Fire and Rescue Services are hoping to avoid a repeat of events on April 30.

About four inches of steady rain dumped on the area led to more than 30 water-related calls and 10 rescues of drivers stranded in flooded roadways.

In case the nearing storm produces similar results, MCFRS is warning motorists to be cautious around Connecticut Avenue at Rock Creek, River Road at Cabin John Creek and along Beach Drive in Rock Creek Park.

It was there that Rock Creek flooded over the Cedar Lane roadway bridge, stranding or incapacitating at least four cars in the matter of minutes on April 30.

“Flash floods more often occur in mountain streams, hilly areas or low-lying areas. But they do happen in urban and suburban areas like Montgomery County, as well,” according to an MCFRS notice put out on Thursday. “Flash floods can occur even though it’s not raining where you are.  It may be raining hard farther upstream and raining so hard that the water can not be absorbed into the ground.”

It can take just six inches of water to reach the bottom of most passenger cars, which could mean a loss of control and stalling.

The long duration of the April 30 rain led to flooding on roadways not particularly close to streams or creeks. One motorist got stranded in a flash flood on Democracy Boulevard.

“Never drive through a flooded road or bridge. Turn Around – Don’t Drown and try an alternate route,” MCFRS said. ”In many cases, it takes far less than a foot of water to incapacitate a vehicle.”