Thunderstorms should pop up over the San Diego County mountains and desert Wednesday afternoon, and some of the storms could spill over into the inland valleys, National Weather Service forecasters say.
“We still have a very moist atmosphere,” forecaster Dan Gregoria said. “There’s a risk of flash-flooding in the mountains, and a lower risk in the desert and eastern valleys.”
The amount of moisture in the atmosphere is 175 to 200 percent of normal for early July, Gregoria said. All that moisture creates the possibility for heavy rainfall rates of as much as a half-inch per hour. Because the storms are expected to move slowly, the risk of flash-flooding increases.
The storms should form around mid to late afternoon. Light winds from the east could push the storms into the valleys, but they are not expected to make it to the coast, Gregoria said. The storms should begin to dissipate after sunset.
Thunderstorms remain a possibility over the mountains on Thursday, but they should be less widespread. The threat of storms continues to diminish over the weekend.
Gregoria said the region can expect warm nights for the next several days, with low temperatures throughout the county about five degrees above normal. Daytime highs should be slightly above average into next week, with the coast mainly in the upper 70s and the valleys in the mid to upper 80s.
“The temperatures stay a little bit above average, but there are no major heat waves like we saw last week,” Gregoria said.