With Another Storm Arriving, Five Areas of California to Watch

SAN MATEO, Calif. — More than two weeks of storms have already hammered California, and one more is on the way over the holiday weekend. The relentless downpours and their impact — flooded homes, flattened cars, downed power lines and more — have killed at least 19 people and disrupted the lives of millions more since late December.

Experts have said that almost none of the storms, alone, would have been considered catastrophic, but the continual pounding has taken a toll on California’s landscape. Soil now struggling to hold water is more vulnerable to mudslides. Days of strong winds have sent trees tumbling. And the relentless precipitation has turned trickling creeks into raging waterways.

Here is a rundown of a few areas officials are watching closely.

Monterey Peninsula

The signature coastal perch of Monterey County, the peninsula is about 100 miles south of San Francisco, home to 50,000 residents and a world-renowned tourist destination that includes the towns of Carmel, Monterey, Pacific Grove and the golfing destination Pebble Beach.

As storms continue to pound the Central Coast, the peninsula has been under close watch. The area expects thunderstorms and between a half inch and one inch of rain through Sunday night, with rain continuing into Monday.

Disaster relief workers have seen widespread flooding in the Salinas Valley, inland from the peninsula, and the county still has active evacuation orders for some areas along the Salinas and Carmel Rivers. On Saturday, more than a hundred people were in evacuation shelters, according to Maia Carroll, the communications coordinator for Monterey County. Some residents have been out of their homes since floods began last Monday.

There were no evacuation orders on the Monterey Peninsula on Sunday, but officials remained on alert across the entire county for more flooding along the major rivers.

The concerns brought back memories of 1995, when roads into the peninsula were flooded, cutting the region off completely from the rest of the county. The main thoroughfares into the region are Highways 1 and 68, which are at risk of flooding if the Salinas River overflows.

Santa Cruz Mountains

Concerns across hard-hit Santa Cruz County, a coastal region south of San Jose, include flooding in the lowlands, a rising tide at the coast and falling trees, but the mountains were uniquely vulnerable to the effects of more rain, said Dave Reid, the director of the Santa Cruz County Office of Response, Recovery & Resilience.

“The challenge for us right now in mountain regions is that any amount of rain, even modest rains, could cause road failures, landslides,” he said. Since the ground has been saturated with rain for weeks, it cannot absorb much more, adding to the potential for mudslides and damaged roads.

Rain was expected for the rest of Sunday into Monday morning in the Santa Cruz Mountains, with a chance of rain continuing into Monday afternoon. Falling trees and mudslides are Daniel DeLong’s primary concerns.

Mr. DeLong, 56, a retired firefighter who lives in Ben Lomond, Calif, a rural town in the Santa Cruz Mountains, describes the recent storms as “much more extreme” than anything he has experienced in three decades living there. His family resides on acres of land full of towering Redwoods and Douglas firs.

“They could just come down and cut your house in half,” Mr. DeLong said. A couple of smaller trees have fallen on his property in the past two weeks but did not cause major damage.

His property is less vulnerable to falling rocks and mud, but the area has experienced road closures from mudslides. Mr. DeLong said it was possible that his family could get trapped on their property should more roads fail.

Lake Tahoe Region / Sierra Nevada

More than eight feet of snow have accumulated in the Sierra Nevada in the last week. Mountain communities in the Lake Tahoe region, with a fleet of snow removal equipment and avalanche professionals, are built to withstand big winter storms. Problems mount, however, on a holiday weekend when that much snow coincides with the arrival of thousands of people looking for a winter getaway in the Tahoe area, one of the most popular places for downhill skiing in the country.

On Sunday morning, bumper-to-bumper traffic inched up two-lane roads toward the ski resorts located north of Lake Tahoe. A winter storm warning issued by the National Weather Service on Sunday forecast another eight to 18 inches of snow to accumulate by Tuesday, with wind gusts up to 80 miles per hour on exposed ridge tops in the Sierra.

California Department of Transportation officials were asking travelers for patience, especially on Monday when continued snowfall was expected to affect road conditions, as tourists return home via high mountain passes. Long delays and slow-moving traffic were expected, Gilbert Mohtes-Chan, a public information officer for Caltrans District 3, said.

When Interstate 80 and Highway 50 experienced delays and intermittent shutdowns on Saturday amid heavy snowfall, Mr. Mohtes-Chan said the roads were “wild” with multiple spinouts and accidents. While stuck in traffic, people jumped out of their cars to play in the snow, forgetting that they were situated on a major thoroughfare where large snowplows and heavy equipment need access. “People need to slow down and be patient, and they’ll get to their destination,” Mr. Mohtes-Chan said.

On the positive side, the amount of water currently contained in the snowpack rivals that during some of the biggest winters in decades. The Sierra is, essentially, a large reservoir for all of California — roughly 30 percent of the state’s water, on average, is from the Sierra snowpack — and snowmelt in the spring keeps a supply of water flowing downstream when the weather turns dry.

Los Angeles County

Downtown Los Angeles received 1.8 inches of rain on Saturday, breaking a record for that date. In the city and surrounding region, the storm inflicted limited damage: A tree crushed several cars; a boulder and other debris from a mudslide shut down traffic. Near the ocean, surging tides caused up to six inches of water to form ponds in streets, including in Long Beach. And a sinkhole that swallowed two vehicles last week in the neighborhood of Chatsworth, in north Los Angeles, continued to expand, stretching across nearly the entire width of the road.

Overall, Mark Pestrella, director of Los Angeles County Public Works, described the situation as “10,000 small cuts across the county.” But they all add up. The road system, he said, with sinkholes and damaged pavement, will cost nearly $200 million to repair, he estimated.

Still, Los Angeles has fared a lot better than other parts of the state, according to Capt. Sheila Kelliher-Berkoh of the Los Angeles County Fire Department. “We’re definitely having our share of things, but it could be worse,” she said.

Ms. Kelliher-Berkoh said that one of the biggest priorities for the department was the Los Angeles River. Often just a stretch of dry concrete cutting south through the heart of the city, the river became a 10-foot deep torrent gushing during the storms, she said. That flow can be particularly dangerous for people who underestimate the power of the current, especially children and homeless people camping near the banks.

The County Fire Department is also closely watching areas recently affected by wildfires, as burn scar areas have left behind loose soil, perfect conditions for mudslides.

Merced County

The county, which sits roughly 130 miles east of San Jose in the San Joaquin Valley and is home to nearly 300,000 people, has endured some of California’s most punishing weather conditions, with last week’s flooding forcing hundreds of people to evacuate from their homes. Among the hardest-hit areas was Planada, a small farming community that sits 90 minutes outside of Yosemite National Park.

The county, part of California’s Central Valley, has seen more than 200 times more rainfall this month than it did last January amid the drought. Storm conditions in the area there eased on Sunday, but locals braced for another round of heavy rain and possible flooding. The rain is forecast to continue through Monday.

During a brief respite this weekend, the California National Guard worked with the county’s Office of Emergency Services to repair and fortify the region’s major waterways, including Bear Creek, which flooded last week.

Emergency workers also scrambled to pump out floodwater before conditions worsened again, clearing storm drains and repairing levees across the valley.

Evacuation orders in Merced County were lifted and roads began to reopen this weekend, giving Red Cross workers, local volunteers and members of the Merced County Sheriff’s Office an opportunity to distribute food and water to weary neighbors.