An atmospheric river dumped more torrential rain on California on Wednesday, forcing evacuations, power outages and road closures, while the remnants of a powerful Nor'easter blizzard buried much of upstate New York and New England under snow.

The West Coast is getting pounded by a usually wet season following two decades of drought, creating havoc on roads and endangering blufftop homes along the coast in southern California's Orange County.

The governor has declared a state of emergency in 43 of California's 58 counties. The San Francisco Bay Area in the western U.S. state of California has suffered the worst power outage in almost three decades, Pacific Gas & Electric Co. (PG&E) said on Wednesday. Some 450,000 customers were affected and at its peak, 367,000 were without power, according to PG&E.

By Wednesday afternoon the heavy rainfall associated with the atmospheric river in California had ended, with only light showers persisting in southern California, but forecasters warned of a possible 12th atmospheric river next week.

Atmospheric river describes airborne currents of dense, tropical moisture from the Pacific. A series of them lashed California in rapid succession from late December through mid-January, killing at least 20 people.

The Sacramento River, the longest in the state, was reaching flood stage just below Shasta Dam, the state's largest reservoir, the National Weather Service said, issuing flood warnings to several towns along the river.

In the northeast, a late-winter blizzard dumped about 2 feet (60 centimeters) of snow in the Berkshire mountains of western Massachusetts and northwestern Connecticut, and a foot or more in parts of New York's Hudson Valley.

Across Massachusetts the accumulations left by the Nor'easter - a type of storm that affects the U.S. East Coast and is named after the direction of the wind - varied greatly. In Colrain, a town of 1,700 in the northwestern part of the state near the Vermont border, 3 feet (91 cm) of snow was on the ground, while Boston's suburbs had about an inch.