Live Updates: Atmospheric River hits Bay Area with heavy rain, threats of flooding

As much of Northern California is getting hit by an atmospheric river, a "bomb cyclone" swept across the northwest US with strong winds and rain, causing widespread power outages and downing trees that killed at least two people.

The Weather Prediction Center issued excessive rainfall risks through Friday and hurricane-force wind warnings were in effect as the strongest atmospheric river - a large plume of moisture - that California and the Pacific Northwest has seen this season overwhelmed the region. The storm system that hit starting Tuesday is considered a "bomb cyclone," which occurs when a cyclone intensifies rapidly.

In California, the weather service extended the flood watch into Saturday for areas north of San Francisco due to "increased confidence in flooding impacts." Higher elevations of the Sonoma County wine region recorded up to 1 1/2 inches (3.8 cm) of rain over 24 hours, forecasters said Wednesday morning. More than 10 inches (25 cm) was predicted for northern parts of the state and down into the central coast. Dangerous flash flooding, rock slides and debris flows were possible, officials warned.

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It is a wet and windy morning in the North Bay as people deal with an increased flood risk.

It is a wet and windy morning in the North Bay as people deal with an increased flood risk.

While the roads have been clear so far, it is a slick commute for North Bay drivers as it pours rain.

If you have to go anywhere during the storm, make sure you take things slow, keep your headlights on, and give yourself plenty of extra time.

A Flood Watch has been issued for the North Bay starting 4 a.m. Wednesday.

According to ABC7 Meteorologist Drew Tuma, rainfall totals Wednesday into Thursday will range from 3" - 7" on the valley floor, 6" - 10" in higher elevations. Those living in flood-prone areas should be prepared to take action should flooding develop.

An atmospheric river storm is expected to arrive in the North Bay late Tuesday before spreading to the rest of the Bay Area later this week, likely bringing several inches of rain and wind gusts of up to 45-50 mph, according to the National Weather Service.

By the end of the week, many parts of the region are expected to receive about a month's worth of rain, with the North Bay forecast to receive up to 10 inches or more in some Sonoma County coastal mountain ranges, weather service meteorologist Dial Hoang said.

"At least for these first couple of days, the North Bay will really see the largest impacts from this system," Hoang said.

As a result of the stormy forecast, Fort Ross and Montgomery elementary schools, both located along the Sonoma Coast, announced they will be closed Wednesday, county education officials said.

Hoang said soil conditions in the Bay Area are somewhat dry because of the hot summer and this being the first big winter storm to hit the region, so that might mitigate flooding concerns somewhat.

"They might be able to soak up some of it initially, but it will saturate really quickly" and lead to flooding in some urban areas and along small streams and creeks, particularly in the North Bay, Hoang said.

Along with warning about the risk of flooding from the heavy rain, the weather service has also issued a Wind Advisory for most of the region that goes into effect at 10 p.m. Tuesday through 6 a.m. Thursday because of a risk of high winds that could lead to downed trees and branches and power outages.

Forecasters are saying there is also a chance of thunderstorms when a second round of rain rolls into the region on Friday and Saturday, and lingering showers are expected to last into early next week.