Pacific Storm Guarantees a ‘Washout’ For California on Sunday

(Bloomberg) -- A powerful Pacific storm is slamming into California and the Pacific Northwest bringing crashing surf, flooding rains that could touch off mudslides, and heavy snow across the region’s higher elevations.   

Drenching rain has already fallen in northern California, with parts of Marin County, north of San Francisco, getting 5.68 inches (14 centimeters), said Scott Rowe, a National Weather Service meteorologist. Flood, wind, and winter storm warnings stretch from the Oregon border to the central California. 

“It is pretty much a slam-dunk guarantee that much of central and northern California can expect a washout today,” Rowe said by telephone. 

Often called atmospheric rivers, big Pacific storms can pump as much water as the mouth of the Mississippi River when they crash ashore. A U.S. Army Corps of Engineers study found such events caused 84% of flood damage across 11 western states over a 40-year period. On average, they cause about $1.1 billion in damage. 

The storm will continue to pump moisture into the region through Tuesday, and as much as 12 inches of rain could fall in some mountains and foothills, leading to mudslides in previously burned out areas, said Lara Pagano, a senior branch forecaster with the U.S. Weather Prediction Center. 

“There could be debris flows associated with burn scars, and we have burn scars peppered through Northern California,” Pagano said. 

Mud from heavy rain can fill a house in seconds, and many areas urged residents to evacuate now or be prepared to do so. Santa Barbara County issued an evacuation warning for several canyons in the area. 

While the heaviest rains are usually associated with higher elevations, Pagano said the valleys will be deluged in this storm. Sacramento could get from 2 to 5 inches of rain, sparking a moderate risk of flooding in California’s capital.

High Surf

Flood watches stretch south from the Oregon border almost as far as Bakersfield, north of Los Angeles, the weather service said. In addition, there’s a high surf warning anticipating waves of up to 30 feet (9.1 meters) smashing into the coastline from Oregon to south of San Francisco. Winds could reach 45 mph, gusting up to 70 mph in some places, and could reach inland into Nevada and Utah. 

The high winds and flooding could cause power outages throughout the region, Pagano said. 

The storm has some positives. It could quench wildfires burning across Northern California and help alleviate drought, which currently affects all of California. 

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