Heavy rains Thursday morning flooded roadways up and down the San Diego County coast, knocked out power in some neighborhoods and led forecasters to issue a flood warning for the San Diego River in Mission Valley. Flooding closed the on-ramp to state Route 78 from El Camino Real in Oceanside, snarle d commutes on Interstate 5 in Del Mar and Sorrento Valley and forced road closures and detours in the Mile of Cars area in National City. Many areas across the county — including downtown San Diego, Mission Valley, Alpine, Poway and Escondido — were drenched with more than 2 inches of rain in just 12 hours, said National Weather Service meteorologist Philip Gonsalves. “Pretty remarkable.” By late morning, the worst of the rain was believed to be over. A widespread flash flood warning issued earlier had expired — but around 10 a.m., the National Weather Service warned of minor flooding of the San Diego River in Fashion Valley. “We had some fairly intense rainfall that was more or less concentrated right in Mission Valley, essentially covering most of the San Diego River basin,” Gonsalves said. “That caused the river to rise rapidly. So right now, it’s above minor flood stage at the Fashion Valley gauge. It’s unlikely to reach major flood stage.” Light showers are expected to move onshore into  the county throughout the day, before the rains move east. But the threat of flash flooding “is pretty much over for the day,” said Gonsalves. Along the coast, the rain is expected to subside — and with it coastal flooding risk — before the last king tides of the season. By mid-morning, roadway flooding had prompted police to warn drivers about I-5 southbound in Del Mar and the Mile of Cars in National City. In Coronado, the Five Points area reopened after being shut down for flooding. Meanwhile, thousands of people lost power around 8 a.m. around the region, including areas of Clairemont, Mission Valley, Tierrasanta, Logan Heights, Mountain View and Lincoln Park, according to San Diego Gas Electric. Some customers in La Mesa and in San Diego’s northernmost neighborhoods were also affected. For the latest on power outages and their causes and when power should be restored, check the utility’s outage map. After the showers taper off later today, forecasters expect drier weather Friday. The weekend will bring more chances of light to moderate showers across the county. ...read more read less