A child separated from his mother on his way to school and swept away in the raging stormwater has been identified.
As of yet, rescuers have so far been unable to find Kyle Doan, 5, after he vanished in the deadly storm that is battering California.
Kyle and his mother were stranded in a truck in rising waters near the city of Paso Robles.
A long and strenuous search has so far only turned up one of the kid's Nike shoes.
Police said in a statement on Tuesday that the search "remains a top priority while weather conditions permit".
At least 17 people have died from storms that began late last month. Rockfalls and landslides shut down roads, and gushing runoff turned sections of freeways into waterways.
Governor Gavin Newsom visited the scenic town of Capitola on the Santa Cruz coast which was hard hit by high surf and flooding creek waters last week.
The deaths included a pickup truck driver and motorcyclist killed Tuesday morning when a eucalyptus tree fell on them on Highway 99 in the San Joaquin Valley near Visalia, the California Highway Patrol said.
Newsom said: "We’ve had less people die in the last two years of major wildfires in California than have died since New Year’s Day related to this weather. These conditions are serious and they’re deadly."
The storm that began Monday dumped more than a 1ft 6ins (45cm) of rain in Southern California mountains and buried Sierra Nevada ski resorts in more than 5ft (1.5m) of snow.
Swollen rivers swamped homes and residents of small communities inundated with water and mud were stranded.
Raging waters crested the banks of Bear Creek and flooded parts of the city of Merced and neighbouring Planada, a small agricultural community along a highway leading to Yosemite National Park.
Neighbourhoods were underwater with cars submerged up to their roofs. Residents ordered to evacuate carried whatever they could salvage on their backs as they left in the rain.
The wet and blustery weather left California's large homeless population in a precarious situation. At least two homeless people in Sacramento County died, and more than a dozen people were rescued from a homeless encampment on the Ventura River.
The latest atmospheric river — a long plume of moisture stretching out into the Pacific that can drop staggering amounts of rain and snow — began easing in some areas.
But more rain was forecast to arrive Wednesday in Northern California, and then a longer storm system was predicted to last from Friday until January 17.
The weather service issued a flood watch through Tuesday for the entire San Francisco Bay Area, along with the Sacramento Valley and Monterey Bay. Areas hit by wildfires in recent years faced the possibility of mud and debris sliding down bare hillsides.
Gusts as high as 88mph (141kph) were recorded in the mountains north of Los Angeles, and rainfall was expected to reach up to half an inch (1.27cm) per hour. Tornadoes that had been forecast never materialised.
In South San Francisco, high winds ripped part of the roof off a large apartment building.
The squalls and flooding have forced school cancellations in some communities and intermittently shut down sections of major roadways that have flooded or been blocked by trees, rocks and landslides.
