SEATTLE (AP) – Northern California and the Pacific Northwest are bracing for what is expected to be the strongest storm of the season so far, with heavy rain and winds set to pummel the region and potentially cause power outages and flash floods.
The Weather Prediction Centre issued excessive rainfall risks beginning yesterday and lasting through Friday as the strongest atmospheric river – long plumes of moisture stretching far over the Pacific Ocean – that California and the Pacific Northwest has seen this season bears down on the region. The storm system has intensified so quickly that it is considered a “bomb cyclone”, explained a meteorologist with the National Weather Service Weather Prediction Centre Richard Bann.
The areas that could see particularly severe rainfall as the large plume of moisture heads toward land will likely stretch from the south of Portland, Oregon, to the north of the San Francisco area, he explained.
“Be aware of the risk of flash flooding at lower elevations and winter storms at higher elevations. This is going to be an impactful event,” he said.
In northern California, flood and high wind watches went into effect, with up to 20 centimetres (cm) of rain predicted for parts of the San Francisco Bay Area, North Coast and Sacramento Valley.
A winter storm watch was issued for the northern Sierra Nevada above 1,066 metres, where 28cm of snow was possible over two days. Wind gusts could top 120 kilometres per hour (kph) in mountain areas, forecasters said.
“Numerous flash floods, hazardous travel, power outages and tree damage can be expected as the storm reaches max intensity” today, the National Weather Service Weather Prediction Centre warned.
Meanwhile, Southern California this week will see dry conditions amid gusty Santa Ana winds that could raise the risk of wildfires in areas where crews are still mopping up a major blaze that destroyed 240 structures.
The Mountain Fire, which erupted November 6 in Ventura County northwest of Los Angeles (LA), was about 98 per cent contained on Monday.
Winds will calm by the end of the week, when rain is possible for the greater LA area.
In southwestern Oregon near the coast, 10-18cm of rain is predicted with as much as 25cm possible in some areas, said Bann.
A high wind warning was issued for the north and central Oregon coast beginning at 4pm yesterday with south winds from 40-64kph, with gusts to 97kph expected, according to the National Weather Service in Portland. Gusts up to 113kph are possible on beaches and headlands.
Widespread power outages are expected with winds capable of bringing down trees and power lines, the weather service said. Travel is also expected to be difficult.
