The threat of thunderstorms in San Diego County mountains and deserts prompted the National Weather Service to issue a flash flood watch effective until 6 p.m. Wednesday.
Rainfall gauges recorded about a quarter-inch of precipitation in Oak Grove and near Ramona between 6 a.m. and noon, and 0.09 inches fell in Palomar.
A flash flood watch means conditions are favorable for thunderstorms that could produce enough runoff to cause flash flooding, according to weather sevice forecaster Mike Watkins.
The unstable weather should move easterly this afternoon, according to the weather service. Runoff from downpours may turn dry washes, creeks, small streams into raging torrents, especially along desert slopes and valley floors, forecasters said.
Rock and mud slides are possible near steep terrain and in recently burned areas, according to the weather service.
Watkins said mountain and desert residents should keep abreast of conditions and stay away from fast-running water.
“There's a saying we have, ‘turn around, don't drown,’” Watkins said.
“In other words, if you see a lot of water across the road, turn around. Don’t drive through fast-flowing water.”