Major storm to bring flooding threat, damaging winds to West Coast

(NEW YORK) — Potential for deadly flooding, damage from incoming monster storm

Potential for deadly flooding, damage from incoming monster storm

Millions in Northern California are bracing for a massive winter storm, just days after the area…

After significant rainfall last week, the West Coast is bracing for another major storm that is expected to bring the threat of flooding rain, damaging winds and mudslides.

A “potent atmospheric river” will start impacting northern California on Wednesday, before moving to the central and southern coast into Thursday, the National Weather Service said.

Damaging winds gusts of at least 50 mph are forecast Wednesday as the front moves in, with gusts up to 70 mph possible near the coast. The gusty winds may down trees and cause power outages, the agency warned.

The storm will bring “substantial rainfall to the San Francisco Bay Area and Central Coast on top of already saturated soils,” the National Weather Service said.

Excessive rain, with river flooding and flash flooding, is possible. Some rivers, like the Russian River, are expected to rise more than 20 feet in just over 24 hours.

“As a result look for rapid rises in area creeks, streams, and rivers. Bankfull exceedance is possible,” the National Weather Service said.

Burn scars will also be vulnerable to flooding, the agency said.

The worst of the storm is expected to hit Northern California and the Bay Area Wednesday afternoon into the evening.

“Between 3 and 7 p.m. you do not want to be on the roads anywhere in the Bay Area,” ABC News chief meteorologist Ginger Zee said.

The heavy rain will move into Los Angeles Wednesday night into early Thursday morning, with flash flooding possible.

Over the next few days, 2 to 4 inches of rain is possible from San Francisco to Los Angeles, with 4 to 8 inches forecast in the mountains.

The excessive rain comes days after San Francisco reported its second-rainiest day ever, when over 5 inches of rain fell on New Year’s Eve.

San Francisco Mayor London Breed said during a press briefing ahead of the storm that the city is anticipating “something just as significant” on Wednesday.

Ahead of the storm, the city activated its Emergency Operations Center to clear storm drains, distribute sandbags and “ensure residents are prepared,” Breed said.

The storm is forecast to then bring heavy snow as it moves into the Rockies Thursday and Friday, where up to a foot of snow is expected. Avalanche danger will be high.

This is the latest atmospheric river storm to bring significant rainfall to the region in recent weeks.

The long, narrow regions in the atmosphere are like “rivers in the sky,” according to the National Oceanic and Atmospheric Administration. They carry large amounts of water vapor over the Pacific Ocean, which is released as rain in lower elevations or snow in higher elevations when they make landfall.

The events are “tied closely to both water supply and flood risks,” NOAA said. Extreme rainfall from an atmospheric river can also cause mudslides, it said.

ABC News’ Max Golembo contributed to this report.