California storms to bury Tahoe under feet of snow. Here's when - and when not - to travel
A snow plow works on Highway 89 in Olympic Valley on Jan. 4. Tahoe roads are expected to be treacherous again next week as long-awaited snow returns. (Brontë Wittpenn/S.F. Chronicle)
Tahoe was covered by a fresh blanket of snow Wednesday, but that's just a sneak peak at what's to come starting Presidents Day.
A parade of storms is anticipated to bring 3 to 7 feet of snow to the Sierra Nevada as the atmosphere settles into a pattern favorable for back-to-back-to-back cold systems. It won't be typical Sierra cement. Temperatures in the teens and 20s will be plenty cold for powdery snow that skiers crave.
Tranquil weather is expected Thursday through Sunday afternoon, but the storm door will swing wide open thereafter.
"Travel ahead of the system will be optimal, with no impacts expected," the National Weather Service in Reno said. "Heavy snow moves in Monday, making travel back after the long weekend very difficult."
The National Weather Service advises only minor Sierra travel impacts through Sunday before conditions deteriorate Monday. (National Weather Service)
Starting Sunday night, a series of systems are expected to drop toward California from the Gulf of Alaska, bringing cold air with them. There may be three of four snowmakers from Feb. 15 through Feb. 22, each capable of dropping 1 to 2 feet of snow across the Sierra. Snow totals along the Lake Tahoe shoreline will remain on the lighter side. Still, accumulations there will likely be on the order of feet, rather than inches.
Confidence is high that temperatures will remain below freezing in Tahoe throughout the storm sequence. The rain-snow line may fall below 3,000 feet by the middle of next week, potentially low enough for significant accumulations along Interstate 5 near Mount Shasta and a dusting of snow atop Mount Diablo and other Bay Area peaks.
Weather models predict the coldest air mass of the season to swing across California next week. The rain-snow line may drop to 3,000 feet or lower. (Baron/Lynx)
Where confidence wanes is regarding the timing of storms and snowfall totals.
While systems originating near Alaska are cold, they contain less moisture than warm pineapple expresses from Hawaii. How much moisture each of these systems picks up on its way to California next week depends just how long they track over the Pacific Ocean.
A bigger dip in the jet stream would yield more moisture, as storms would have more time to evaporate water from the relatively warm seas below. A straight path from Alaska to California would bring chillier air, but less rain and snow.
Weather models are fluctuating with the track of the jet stream over the northeast Pacific Ocean early next week. A linear path from Alaska to California would bring cold air and less rain and snow, while a dip in the jet stream like the map above would yield much more precipitation. (Baron/Lynx)
Because of the uncertain jet stream position, the onset of snow is still up in the air.
Snow could begin as early as midday Sunday or as late as Monday afternoon. Regardless, once snow starts falling, there may not be a significant break for five or six days.
"It is likely that we will be seeing some pretty snowy roads, so … chain controls, travel delays and maybe even road closures depending how bad it gets," said Gigi Giralte, a meteorologist at the weather service office in Reno.
People traveling to and from the mountains next week should prepare for winter driving conditions. The weather service advised people to "consider adjusting travel plans."
Winter recreationalists are awaiting the storm parade, as a long slog of warm, dry weather has left some ski areas barren, including Mt. Shasta Ski Park, which announced a temporary closure earlier this week.
"It's been a hot second since we got a good dumping of snow in the Sierra," Giralte said.
Feb. 11 snowpack in the northern Sierra, Trinity Alps and southern Cascades was just 40% of average. Higher elevations of the central and southern Sierra were faring better, but the snowpack in those areas was still well below normal for this time of year.
Next week's storms won't completely wipe away the Sierra snow drought, but they'll certainly help cut into the deficit. Long-range forecasts favor drier weather in late February.
