Major Thanksgiving snowstorm to delay truckers out west: flooding in some valleys

The first snowstorm of the season for the Sierra Nevada Mountains will arrive just in time for Thanksgiving, and it’s supposed to be a big one. Anybody eagerly awaiting a trip to places like Lake Tahoe or Yosemite National Park for some holiday fun should plan to get there by lunchtime on Wednesday before travel becomes risky or impossible.

Same goes for fleet managers who have to send drivers into eastern California and western Nevada. With more than 12 inches of snow in the forecast for the highest elevations, it’ll be difficult to get trucks through mountain passes unless drivers go far out of their way to avoid the storm altogether.

Drivers who decide to brave the storm will have to be extra careful on I-80 through Donner Pass. Travel could also be very difficult over the Mount Rose Highway, Carson Pass, and Monitor Pass. Expect Ebbetts Pass, Sonora Pass, and Tioga Pass (SR-120) to close. Travelers should be prepared for long delays on I-80, as well as US-50 around Lake Tahoe. Strong winds and blowing snow will limit visibility and make deadheading or hauling light loads dangerous.

Typically, the Sierra isn’t a stranger to heavy snow in late November. Meteorologist Jeff Barlowe of the National Weather Service office in Hanford, California tells FreightWaves that by Thanksgiving there’s often three to four feet of  it on many of the mountain tops. He also says an average snowstorm this time of year produces 12 inches or more above 8,000 feet.

But the region hasn’t had precipitation of any kind for 45 days, and along with the mountain snow will come plenty of valley rain. Barlowe says only a small amount of rain could cause mudslides and debris flow into the Yosemite Valley where the Ferguson Fire burned down forests earlier this year. This could prompt evacuations from the towns of El Portal and Midpines, also affecting travel on SR-140.

Here’s the breakdown of where to expect the heaviest snow and strongest winds.

Sierra Nevada from Yosemite to Kings Canyon and Tulare County Mountains

• Total snow accumulations of six to 15 inches expected above 7,000 feet, with up to 20 inches possible in some spots.

• Most of this snow will fall from Wednesday afternoon through Thanksgiving morning.

East slopes of the southern Sierra including Mount Whitney

• Total snow accumulations of six to 10 inches are possible above 8,000 feet, four to seven inches between 7,000 and 8,000 feet, and generally four inches or less can be expected below 7,000 feet.

• Winds will gust to more than 60 mph over passes and ridge lines.

• Most of the snow and wind will occur from Wednesday afternoon through Thanksgiving morning.

Western Plumas County/Lassen Park and west slope Northern Sierra Nevada

• Total snow accumulations of four to ten inches expected with localized amounts up to 15 inches possible.

• Most of the snow will fall from Wednesday afternoon through the morning of Black Friday.

Greater Lake Tahoe area and Mono County

• Total snow accumulations of six to 12 inches expected above 8,000 feet; between 7,000 and 8,000 feet four to eight inches are possible, with four inches or less below 7,000 feet.

• Winds could gust as high as 60 mph through passes and over ridge lines.

• Most of the snow and wind will occur from Wednesday afternoon through late Wednesday night.

This storm will likely create hazardous hiking and camping conditions. The National Weather Service urges outdoor enthusiasts to be prepared for extreme winter weather conditions or avoid the high Sierra during this storm. Stay up to date on winter weather alerts on this interactive map.

This storm will also drop heavy rain onto northern California, including Butte County where the Camp Fire is still burning. While the rain will help put out the fire and clear the air of thick smoke, the rain could cause rock slides, landslides, and debris flow in parts of the Sacramento Valley. This will make the search for hundreds of missing people more difficult and dangerous. This could delay travel on I-5 and SR-299 through Redding, and along portions of SR-70. The latest road closures in California can be found on this web site.