California braces for more rain
It’s raining in California. Again. A storm system hitting north and central California on Monday and today will deliver 2 to 3 inches of rain to the valley, and up to 10 inches of rain to the mountains, said Eric Kurth, a meteorologist with the National Weather Service in Sacramento. The service has issued a flood warning through Wednesday across most of the Sacramento River Valley and the surrounding areas.
It is the latest in a string of storms this winter that have dropped an unusually high amount of water on the state, which had spent more than five years under dire drought conditions.
“On its own, this system wouldn’t be much of a concern,” Kurth said. “But we have elevated stream levels, river levels. We are seeing some of the rivers up at flood levels.”
Last week, more than 180,000 residents were ordered to evacuate from below the Oroville Dam when a damaged emergency spillway and a swollen reservoir raised concerns about a collapse. Crews rushed to fix the damaged embankment at the dam, 70 miles north of Sacramento, and to prepare it for more rain.
On Saturday, a storm with winds near hurricane strength swept through Southern California, killing at least two people, flooding roads and triggering mudslides. A sinkhole in Studio City swallowed a car.
Interstate 5 in the central Sacramento Valley was flooded briefly over the weekend. “That was an area that typically we don’t see much flooding,” Kurth said. “But things are so saturated.”
Rivers are near flood stage already
Across the northern part of the state, swollen rivers were lapping over their banks and reservoirs were close to flood stage. The National Weather Service reported nearly a dozen rivers were at their flood stage Sunday.
The San Joaquin River was at “danger stage” Sunday and nearing the top of its levees at a measuring station
near Vernalis, Tim Daly, a spokesman with San Joaquin County Office of Emergency Services, told The Associated Press.
In Colusa County, about 60 miles north of Sacramento, Jim Saso, the assistant sheriff, told the AP that he was warning residents to be prepared for evacuation. “We’re telling those people to keep a bag close by and get ready to leave again,” he said.
The Don Pedro Reservoir in Tuolumne County, southeast of Sacramento, was at 826 feet on Sunday — 4 feet below its flood level, CBS 13 reported. Authorities were preparing to release water through its spillway as early as Monday afternoon, the first time in 20 years that would have happened, CBS 13 said.
How bad could it be?
The ultimate effect of the storm depends on how much of the moisture lands as rain in the valleys as opposed to snow higher up in the mountains, Kurth said.
“That set of storms previously that brought a lot of trouble, the issues with the Oroville Dam, that system was very warm,” he said. This storm is not quite as warm, meaning that some of the higher amounts of moisture could be in the form of snow in the mountains and would not effect the rivers immediately.
What is causing this rain?
This latest storm is what’s called an “atmospheric river” — a weather event more commonly known as the “pineapple express.” It is moist tropical air from the central Pacific trapped in a band between different pressure systems, Kurth said. When it hits California, it unleashes a high amount of rain.
“It’s like a fire hose of moisture when we get these atmospheric rivers,” he said.
What else can happen?
This storm also brings “pretty strong winds,” which could potentially top 60 mph Monday evening, Kurth said.
The wind, when combined with the oversaturated ground, means that trees tend to topple more frequently — and when they do, they often take powers lines with them. Or they fall across highways, snarling traffic in regions that were spared flooding.
“I’ve seen more of that this year than I’ve ever seen by far,” Kurth said.
The saturation also leaves areas vulnerable to mudslides. “Major arteries over the Sierras have been blocked for long periods of time, and I expect we’ll see much more of that today, too,” he said.
What does that mean for the drought?
California has been in a drought for more than five years, resulting in mandatory conservation. Reservoirs were parched, and the snowpack that helps feed the state’s rivers and streams with its spring thaw had been nearly nonexistent at times.
But this year has brought a tremendous amount of rain and snow, and that has helped.