Winter Storm Warning as California Travel Could Become 'Very Difficult'

A winter storm warning is in place for parts of California as the state braces for a stream of rainfall and snow at higher elevations on Thursday, bringing the risk of flash flooding in places.

The National Weather Service (NWS) issued an alert for the Sierra Nevada mountain range from Yosemite to Tulare County, warning of hazardous conditions and blowing snow that "could significantly reduce visibility" and impact the morning and evening commute.

The warning covers areas more than 8,000 feet above sea level and lasts until 10 a.m. PT (1 p.m. ET) on Thursday. Between three and six inches of snow accumulation is expected at elevations of 8,000 to 9,000 feet, while as much as a foot could settle at higher levels.

With wind gusts anticipated to reach up to 45 mph, the agency warned that travel "could be very difficult," and urged motorists to keep emergency supplies, including a spare flashlight, food and water, in their vehicle.

Western states have faced several bouts of snowfall so far this winter, having been subjected to a "prolific series" of atmospheric river storms from the Pacific. Last winter, the West Coast experienced the effects of a similar weather front, with California seeing several rounds of flooding.

Higher-elevation regions in Colorado, New Mexico and Wyoming have recently seen more than a foot of snow in some parts as winter weather takes hold early in the season.

In its latest forecast, the NWS said that a southward-moving storm would bring a stream of moisture into California, causing rain and snow at higher elevations, before moving into Mexico on Saturday.

It added that the storm will "produce heavy rain over much of coastal California and inland," with the risk of excessive rainfall over southern California through Thursday.

"The associated heavy rain will create numerous areas of flash flooding with narrow canyons/gullies and burn scars the most vulnerable," the NWS warned. "Furthermore, many streams may flood, potentially affecting larger rivers."

Rainfall over northern California is expected to subside by Thursday, while lighter rain is anticipated over parts of the southern Rockies on Wednesday night.

The warning comes after states on the East Coast were battered by a deadly storm earlier in the week, leading to felled trees and downed power lines, with hundreds of thousands of power outages recorded in New England.

On Monday, the California Governor's Office of Emergency Services urged residents to prepare for adverse weather conditions through this week and into the next, advising them to have emergency plans in place and to avoid unnecessary travel in areas that may be subject to flooding.

It said a "persistent atmospheric river will continue to develop with moderate to heavy rainfall" over the state, and that "additional storms may continue to develop across the state through the holiday season."