Blizzard, flooding and wind damage possible in western U.S.

A mix of messy weather is heading to California this weekend, slowing down drivers and delaying the movement of goods. A series of storms currently off the Pacific Coast will dump heavy rain along the coast and Sierra foothills, beginning tonight (Friday), while snow returns to the Sierras’ high elevations after a relative lull since a mid-January onslaught. Besides unsafe driving conditions and possible flooding, the storms could produce wind damage.

Snow and Wind

Some of the worst weather will occur in the vicinity of Lassen Volcanic National Park and the west slope of the northern Sierra Nevada Range. This is where snow accumulations could total 36 inches, with localized accumulations of up to five feet in the highest elevations. Snow levels will start around 6,000 feet tonight, then drop to around 4,000 feet by Sunday. On Monday, snow levels will continue to fall to the 1,000- to 2,000-foot range, with accumulating snow possible for the coastal range foothills.

The South Lake Tahoe area will get hit hard, too, including the nearby cities of Incline Village, Stateline and Truckee, where three to six feet of snow could pile up on peaks above 7,000 feet; two to four feet at lake level. Whiteout conditions are likely on Sunday and Monday as wind gusts reach 50 mph in many spots, and up to 100 mph over ridges. Travel will be very difficult to impossible.

Mono County in northern California is another area to watch closely, including the cities of Bridgeport, Coleville and Mammoth Lakes. Look for total snow accumulations of eight to 20 inches along US-395, except two to five feet above 7,000 feet in areas west of US-395. Winds
will be strong here, too, gusting to 50 mph Sunday afternoon through Monday, with gusts of 100 mph on the highest ridge tops. Blizzard conditions will severely limit visibility, in addition to increasing the risk of deadheading or carrying light loads.

It will also be difficult getting through Portola and Susanville, with heavy snow totals of up to eight inches on valley floors, and up to 16 inches above 5,000 feet. West of US-395 will get much more snow – one to three feet – along with strong winds gusting to 40 mph Sunday afternoon through Monday.

Other areas like Aspendell, Grass Valley, Kings Canyon National Park, Lake Shasta, Siskiyou County, Whitney Portal and Yosemite National Park will receive anywhere from several inches to two feet of snow, accompanied at times by strong winds. Trees and power lines could be blown down, leading to potential roadblocks and scattered power outages across the Sierras.

Rain and Wind

Powerful crosswinds will give truckers a tough time along the I-5 and US-101 corridors, as well as the Pacific Coast Highway (PCH), especially Friday night and Saturday. Gusts could reach 55 to 65 mph, with isolated gusts of 75 mph in the foothills, from the entire San Francisco Bay area to the Los Angeles metro area.

But Mother Nature won’t stop there. Abnormally high amounts of rainfall are likely, with four to seven inches possible in the mountains and foothills east of Los Angeles, as well as two to four inches in the foothills of the Sierras and in parts of the San Francisco Bay area. Heavy rainfall rates and excessive runoff could lead to flash flooding across roads and intersections. Another unfortunate byproduct could be mudslides and debris flows. Some places near San Diego – Palomar Mountain, for instance – could get two to three inches of rain.

Although no Flash Flood Watches have been posted yet for San Diego County, the National Weather Service (NWS) has issued them for other areas.

Other Notable Weekend Weather

There’s an elevated risk of blow overs along I-25 and I-80 in southeastern Wyoming. Drivers will need to be extra careful going through the Casper, Cheyenne, Laramie and Medicine Bow areas. Wind gusts are forecast to reach 60 to 65 mph.

In addition, a snowstorm will move across the Cascades of Washington State from Saturday night through early Monday, as well as the northern Rockies of Montana and Idaho. Blowing snow could reduce visibility at times on portions of I-15 and I-90.

Look for updated NWS alerts on this interactive map, and have a safe weekend!