Holiday Travelers in California Face Heavy Rain, Snow as Another Storm System Approaches

California is bracing for a week of winter storms amid La Nina conditions in the Pacific Ocean. Heavy mountain snowfall and widespread rain are expected. People planning on traveling for the holidays need to be prepared, as the weather could cause some delays.

The National Weather Service said that from Tuesday to Sunday, parts of Northern California could see 1 to 5 feet of snow, with higher elevations potentially getting up to 8 feet. The storm could produce significant levels of snow for lower elevations as well.

The area over Interstate 5 north of Redding, California, which was shut down for 24 hours last week due to storms, could see more snow accumulation, forecasters said.

"Gusty winds will further reduce visibilities during this event with local whiteout conditions possible," forecasters said. "Holiday travelers should prepare for winter driving conditions by packing chains, warm winter clothes, and extra food and water."

The National Weather Service warned people traveling in the mountains to proceed with caution, as travel difficulties are to be expected.

Wet weather for Southern California is predicted later this week. Forecasters said rain and high-elevation snow are likely for Wednesday through Thursday, with more showers throughout the weekend.

Yosemite National Park, California, Snow
The National Weather Service warned people traveling in California's mountains to proceed with caution, as travel difficulties are to be expected with approaching winter storms expected later this week. Above, heavy snow begins to fall in Yosemite Valley, California, as a major Pacific storm pushes into the region on December 14. George Rose/Getty Images

The Los Angeles weather office said water vapor imagery over the Pacific shows an atmospheric river developing as moisture streamed from an area east of Hawaii.

Atmospheric rivers suck up water from the Pacific and dump it in the form of snow and rain when they arrive at the U.S. West Coast.

In October, the National Oceanic and Atmospheric Administration announced that the Pacific Ocean was showing signs of a new La Nina, the flip side of the El Nino ocean-warming pattern, that tends to cause changes in weather worldwide.

Forecasters said much of California would have a 33% to 50% chance of below-normal precipitation, while only the state's far northern tier had equal chances of above- or below-normal precipitation.

But the storm track has trended farther south than is usual during La Ninas. After a series of mid-December tempests, California's overall snow-water equivalent—a measurement of how much water is in the snowpack—jumped from 19% of normal to date on December 10 to 76% of normal on December 17, according to the latest U.S. Seasonal Drought Outlook.

While the current wet trend is positive, it is too early to know if it will last through January and February. The snowpack normally doesn't reach its maximum until April, and last spring there was minimal runoff because much of the water was absorbed by the drought-parched landscape.

The mountain range, where ski resorts had struggled to open this fall, is already sporting glistening peaks after recent storms. The snowfall is important because the winter snowpack normally is a significant source of California's water.

The Associated Press contributed to this report.

California, Snow, Rain, Flooding
A major winter storm hitting Northern California is expected to intensify and bring travel headaches and a threat of localized flooding after an abnormally warm fall in the U.S. West. Light rain and snow that started falling over the weekend was heavier early Monday. In this image taken from a video from a Caltrans remote video traffic camera, a truck makes its way through the snow along Interstate 80 at Donner Summit, California, on Monday, December 13. Caltrans/AP Photo