California atmospheric river: Some California residents are urged to prepare 2 weeks of essentials ahead of expected flooding this week

CNN
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California officials are urging residents to prepare for a powerful storm to lash the region with heavy rain this weekend as the state continues to recover from heavy snow that has trapped mountain communities.

About 16 million people in central and northern California, including the San Francisco Bay Area and Sacramento, were under a flood watch early Wednesday ahead of a storm that was set to drench the region with dangerous amounts of rain Thursday — heavy in some places. On the existing layers of ice.

“Combination of heavy rain and snowmelt could lead to flooding,” Weather Prediction Center said. “Streams and streams in the western foothills of the Sierra Nevada will be most vulnerable to flooding from rain and snowmelt.”

The ominous forecast comes as several rounds of heavy snow have hit much of California, trapping mountain residents in their homes, making roads impassable for days and thousands of residents as temperatures plummet. The electricity has been turned off.

In addition to the heavy snowfall in the state last week, some mountainous parts of Northern California have already received more than a foot of additional snow this week. And Wednesday is expected to bring more to the region, where lower elevations could see between 1 and 6 inches of snow, with the highest elevations of the Sierra Nevada mountain range surpassing a foot of snow.

Closer to the coast, officials in Marin and Monterey counties have begun preparations days ahead of the impending storm, which is expected to hit the region as a strong atmospheric river event.

For the Big Sur community in Monterey County, the Office of Emergency Services advises residents and businesses to stock up on essential items that will last them at least two weeks. The county has done it too Sandbags are available for residents Those who need to protect their assets.

County Fire Chief Jason Weber said the Marin County Fire Department will have staff ready to respond in anticipation of possible flooding.

“All our reservoirs are full from the storms earlier this year. With reservoirs filled, we expect our rivers to rise more rapidly with most of the rain runoff,” Weber told CNN.

Marin County, where a flood watch is in effect starting Thursday, is home to California Urban Search and Rescue Task ForceAnd it will make its resources available to other counties as needed, Weber said.

This week’s projected atmospheric river event won’t be the first to hit California this year. Late last year and into the new year, several rounds of heavy rain from atmospheric rivers ravaged much of the state – drenching entire areas and killing at least 18 people.

Atmospheric rivers are long, narrow bands of moisture in the atmosphere that transport warm air and water vapor from the tropics. They can spread thousands of miles and can drop rain and snow when they make landfall.

Much of California will be affected by this week’s possible atmospheric river.

The Weather forecast center says there is a Level 4 risk of heavy rain in parts of the state from Thursday to Friday – the second-highest on the Centre’s scale.

The storm is expected to drop some significant rainfall on top of some heavy snowfall. The National Weather Service is expecting widespread rainfall totals of 2 to 4 inches with isolated amounts of up to 8 inches.

“The uncertainty lies in how much precipitation will be absorbed by the snowpack before there is a significant release of that water into rivers,” the Weather Prediction Center said. “Some (precipitation) will likely be absorbed into several feet of snow at the highest elevations, but lower elevations, typically below 5,000 feet, will likely have enough snow to absorb several inches of rain. The possibility of not being packed appears. ”

In addition, the threat of heavy rain in the deep snowpack could increase the weight of the snow, causing roofs to collapse, the forecast center noted. The weather agency added, “Affected communities are urged to remove existing snow from their roofs to minimize this.