SAN DIEGO (CNS) - Scattered afternoon and early evening thunderstorms are expected in the mountain and desert areas of San Diego County for the second consecutive day Tuesday, posing a threat of flash flooding.
According to the National Weather Service, summer thunderheads full of subtropical moisture out of Mexico generated about 1,000 cloud-to-ground lightning strikes Monday afternoon. The flashing bolts and thunderclaps were accompanied by heavy showers that submerged several stretches of roadway, but there were no reports of injury, fire or property damage, NWS meteorologist James Thomas said.
"A very moist and unstable air mass will remain over the mountains and deserts of Riverside and San Diego counties through (Tuesday) evening," a Weather Service advisory said.
The agency scheduled a flash flood watch for the mountains and deserts from 11 a.m. to 11 p.m. A flash flood watch means excessive runoff from heavy downpours may cause rapid filling and overflowing of normally dry washes and small creeks.
There is also a threat of rock and mud slides below steep terrain in the mountains and recently burned areas, according to the Weather Service.