Sierra travelers trapped by back-to-back storms that dropped more than 2 feet of snow have a brief window to pass before the arrival of a weather system Saturday so wet forecasters are calling it an "atmospheric river."
Up to 12 inches of rain below 8,500 feet is expected, and massive amounts of snow — up to 6 feet — above that elevation. A fourth, colder storm two days behind will drop yet more heavy snow.
“It’s a once-in-10-year event,” said Zach Tolby, a meteorologist with the National Weather Service in Reno. “It’s the strongest storm we’ve seen in a long time, the kind of setup we look for to get significant flooding.”
The atmospheric river, or “Pineapple Express,” will be felt across much of California this weekend, though rains will be much heavier in the north than in the south.
Tolby said the storm is packing the same wallop as an atmospheric river that hit Northern California a decade ago that caused $300 million in damage, according to the U.S. Geological Survey.
Angelenos may remember the 2005 storm because it was the first time it rained on the Rose Parade in 51 years. But Tolby, who lives in Lake Tahoe, remembers the storm differently.
“It was pretty wild. I was here in 2005 and it was definitely the hardest rain I’d ever seen. It didn’t stop for 24 hours,” he said.
This weekend’s storm could bring 36 straight hours of heavy rain from Mammoth Mountain to Susanville, Tolby said.
In the mountains, the rain could pile onto the snow and trigger early snow melts, feeding extra water into watersheds already swollen from a week of rain.
“A combination of intense rain on saturated soils will lead to excessive runoff,” the National Weather Service said in its weekend forecast.
The Carson, Truckee and Susan rivers are all expected to become overwhelmed, and the nearby communities may become increasingly isolated if the deluge triggers mud flows and rock slides.
In Mono County, authorities offered sandbags to residents in preparation for the rain. In Yosemite National Park, authorities were cautioning visitors to check with the park before heading in — the weekend storm could close Yosemite if the Merced River floods, they said.
Colfax, known as the turnaround town, is ready.
"It's something we prepare for — it goes with the snow, hand in hand," said Wes Heathcock, community services director for the tiny Placer County town that has perhaps one of the most used Interstate 80 on/off ramps in Northern California when it is a snow day.
When snow conditions become too treacherous, the California Highway Patrol typically closes Interstate 80 at Colfax, as it did Wednesday during a snowstorm that also brought a car-semi collision. Perched at an elevation of 2,400 feet, Colfax bills itself as "above the fog, below the snow."
The options for stranded travelers are slim in the Old West railroad town, whose most famous mention is a passing reference in Jules Verne's “Around the World in 80 Days.” Even Phileas Fogg did not stop.
There is a Starbucks and a single motel.
"They're welcome to spend some tax money in Colfax, but generally you'll see they'll trickle back down, try to locate hotels a little closer to the [Sacramento] Valley," Heathcock said.
Colfax gears up for the die-hards, travelers who believe the solution to snow-blocked passes is to find another route to the same location.
"We all have this wonderful tool called GPS now," Heathcock said.
From Colfax, California Highway 174 makes a long northerly loop to the narrow, hairpin turns of Highway 20, eventually depositing drivers into the thick. They hit Interstate 80 at Yuba Pass, just before Donner Summit.
During Wednesday's storm, the city's public works crew joined the sheriff and California Highway Patrol to stand along that road and ward off drivers seeking the bypass.
Wednesday's storm dropped up to 2 feet of snow in less than 24 hours in the Tahoe basin, at times coming down at more than 2 inches an hour.
The Sierra Avalanche Center reported a slight improvement in backcountry conditions. The risk of avalanche was lowered to "considerable" even as the threat increased of historically large avalanches caused by slabs of snowpack as thick as 8 feet above a weak layer of ice laid down by a mid-December rain.
Near Lake Tahoe on Thursday, two skiers were caught in an avalanche that closed a local highway. But they were not injured, officials said.
Sierra residents are preparing for a third onslaught over the weekend, bringing up to 12 inches of rain below 8,500 feet, and more snow above that. A fourth storm system is forecast to roll across Northern California two days after that.
After the weekend storm, another rain-making system is expected to hit Northern California on Tuesday.
The storm moving through Southern California was significantly smaller than the one in the north. But it still caused problems.
Rain-slicked roads were clogged with commuters after a big rig jackknifed on the eastbound 60 Freeway in East Los Angeles, forcing authorities to shut down five lanes. In Burbank, several lanes were blocked after a semi-truck jackknifed across north and southbound lanes of the 5 Freeway.
By midmorning, firefighters rescued a man who was stranded on an island of branches and brush in the rain-swollen Los Angeles River near Fletcher Drive in Silver Lake, said Brian Humphrey, a spokesman for the Los Angeles Fire Department.
Though the rain subsided Thursday afternoon, the problems kept coming. Crews were forced to temporarily close the northbound 710 Freeway north of the 5 Freeway to replace concrete slabs damaged by the weather, the California HIghway Patrol said.
For all the problems the storms may cause, it will bring more good news for California’s six-year drought. Officials have said steady rain in Northern California the last few months has filled reservoirs and increased the once-anemic snowpack.
They emphasize the storms won’t end the drought. But if the rains keep up for spring, they could make a major dent.