The California-Oregon region is bracing for the first major storm of the season, an atmospheric river that potentially could dump nearly 10 inches of rain on the greater Redding area by the weekend.

And while the calendar still says fall, the storm kicks off with wintry conditions driven by low snow levels.

“It’s definitely our first significant storm. I would say depending on how you want to define winter, I suppose you could call it the first winter storm,” Sara Purdue, a National Weather Service meteorologist, said on Monday.

When does the storm hit Oregon-Northern California?

Much of the rain and snow that will fall on the area will happen Tuesday and Wednesday, according to the National Weather Service.

The Northern Sacramento Valley, including Redding, is expected to get 6 to 8 inches of rain Tuesday through Friday, according to the National Weather Service.

The heavy rain has prompted the Weather Service to issue a flood watch for the Northern Sacramento Valley from Tuesday evening through Saturday morning.

There is a winter storm warning for the mountains and foothills of Shasta County that is in effect through Wednesday night. The National Weather Service forecasts 8 to 18 inches of snow above 4,500 feet and 4 to 8 inches above 3,000 feet.

Snow is not expected to fall as low as the valley floor.

For Siskiyou County and the Mount Shasta-Shasta Valley area, there is the potential for 8 to 12 inches of snow Tuesday and Wednesday, said Alexis Hermansen, a National Weather Service meteorologist.

Snowfall accumulations will be higher in the mountains surrounding the city of Mount Shasta.

“We could see a foot and a half to over 2 feet,” Hermansen said.

Winds also will be a concern in the Shasta Valley north of Mount Shasta, with gusts possibly up to 70 mph Tuesday night through Wednesday morning, the National Weather Service said.

Snow levels will increase to over 6,000 feet into Thursday and Friday.

Drivers on I-5 be prepared; carry snow chains

Mountain travel Tuesday and Wednesday will be especially challenging with the lower snow levels.

Chris Woodward, spokesman for the California Department of Transportation, said chain controls are expected to be in place at the higher elevations of Interstate 5 north of Redding.

“The most important thing motorists need to know is to be prepared, have those chains when you need to have them,” Woodward said.

Caltrans recommends drivers check their brakes, battery, windshield wipers, defroster, heater, headlights and exhaust system before traveling in the mountains.

In addition to packing chains, Woodward said drivers should have an ice scraper and shovel, flashlight, warm blankets, water, non-perishable food items and a cell phone.

Motorists can check road conditions on the Caltrans’ QuickMap site at https://quickmap.dot.ca.gov.

There is also a chance Caltrans and the California Highway Patrol will screen motorists for chains 10 miles north of Redding on I-5 at the Fawndale exit, Woodward said.

Screening vehicles allows authorities to meter traffic traveling through the Sacramento River Canyon, which can get treacherous and often is closed temporarily due to big-rig trucks and other vehicles spinning out on I-5 during heavy snowstorms.

“When we need to close the interstate, that screening acts like a kink in the hose, slowing that interstate traffic down and moderating the traffic,” Woodward said.

Thanksgiving travel outlook

This week’s storm is expected to linger through the weekend.

Purdue of the National Weather Service in Sacramento said Monday that it’s still early to get an accurate forecast for the busy Thanksgiving week.

“Potentially, there will be a damp start — I won’t say wet start — but damp start to the beginning of next week,” she said.

AAA projects 80 million travelers will head 50 miles or more from their homes next week.

The extended holiday forecast, which includes the Tuesday (Nov. 26) before Thanksgiving and Monday (Dec. 2) afterwards, is expected to exceed pre-pandemic Thanksgiving travel levels and set a record, AAA said.

David Benda covers business, development and anything else that comes up for the USA TODAY Network in Redding. He also writes the weekly “Buzz on the Street” column. He’s part of a team of dedicated reporters that investigate wrongdoing, cover breaking news and tell other stories about your community. Reach him on Twitter @DavidBenda_RS or by phone at 1-530-338-8323. To support and sustain this work, please subscribe today.