SAN DIEGO -- The first storm of the year's rainy season moved into the San Diego area Tuesday, bringing significant showers along with scattered thunder and lightning.
The atmospheric collision of one low-pressure system out of the south and another, colder one making its way along the coast from the north brought widespread precipitation across the county by late afternoon, according to the National Weather Service.
The wet and unsettled conditions will continue through Thursday night, with the heaviest rainfall expected to fall Wednesday, meteorologist Miguel Miller said.
Due to the expected intensity of some of the downpours, the NWS issued a flash-flood watch, effective through late Wednesday night in the local mountains, valleys and coastal areas.
As of 4:15 Tuesday afternoon, according to the weather service, the bands of dark clouds had dropped 2.09 inches of moisture in Valley Center, 1.38 in Rincon Springs, 1.29 in Deer Springs, 1.16 in the Palomar Mountain/Pala area, 0.96 in Escondido, 0.77 in Skyline Ranch, 0.75 in La Jolla and 0.71 at Lake Wohlford.
Other rainfall totals included 0.7 of an inch in Rancho Bernardo, 0.63 in Ramona, 0.5 at Mount Woodson, 0.46 in San Marcos, 0.43 in Elfin Forest, 0.38 in Barona, 0.31 in Poway, 0.28 at Miramar Lake, 0.25 in Flinn Springs, 0.14 in Lakeside, 0.09 in El Cajon, 0.08 in Encinitas, 0.06 in Kearny Mesa, 0.04 in Del Mar and 0.01 in Carlsbad.
By 4 p.m., the NWS had tallied 24 cloud-to-ground lightning strikes in the San Diego region.
Temperatures across the county are expected to drop to 15-20 degrees below average on Wednesday, pushing the snow level down to around 6,000 feet, or about 500 feet lower than the highest local mountaintops, forecasters said.
The storm system will move out of the area over the day Thursday, the weather service advised. There will be a slight chance of showers late Friday into early Saturday, after which mostly dry conditions will prevail into early next week, according to meteorologists.