A Pacific storm is expected to drop heavy snow and strong winds on the Sierra Nevada on Friday, with blizzard conditions possible above 7,000 feet and dangerous travel over Donner and Echo summits, the San Francisco Chronicle reported Wednesday. The same system is forecast to bring rain and gusty winds back to the Bay Area, ending a stretch of dry, mild weather that has covered Veterans Day.
The National Weather Service office in Reno, in an area forecast discussion issued early Wednesday, said winter storm watches are in effect for the Tahoe Basin and Mono County from Friday afternoon through Saturday morning. Snow levels are expected to start around 7,500 to 8,000 feet, then fall to near 6,000 feet by midnight. The heaviest snowfall rates, the office said, will arrive late Friday night into early Saturday, reaching 2 inches an hour at times. The Chronicle said forecast totals have risen to 8 to 18 inches at many higher elevations, including Donner Pass, and 18 to 24 inches along the highest peaks, with the worst conditions Friday evening into early Saturday along Interstate 80 over Donner Summit, Highway 50 over Echo Summit and other high passes. Chain controls, delays and temporary closures are possible.
ABC7 meteorologist Drew Tuma said the Friday system has been upgraded to a Level 2, the first moderate storm of the season, and should end fire season. Many Bay Area cities are likely to see about a half-inch of rain, with totals ranging from a half-inch to more than 1.5 inches in the North Bay and Santa Cruz Mountains, and wind gusts of 30 to 50 mph. The worst rain and wind, Tuma said, should arrive between 10 a.m. and 2 p.m. Friday and is not expected to disrupt the morning commute much, with showers and a chance of thunderstorms later in the day. ABC7 also said 20- to 30-foot surf is expected along the coast Friday into Saturday under a high surf warning already in effect.
Snow totals at lake level still differ by forecast. ABC7 put the first accumulating Sierra snow of the season at 6 to 12 inches at lake level and more than 18 inches on the highest peaks. The Chronicle said rain should reach the Tahoe Basin before sunset Friday, with accumulating snow possible in Truckee, South Lake Tahoe and other communities near the rain-snow line overnight; it put roughly 8 to 12 inches at the base of Palisades Tahoe by late Sunday, 3 to 6 inches in Truckee, and 2 to 6 inches in South Lake Tahoe, with locally higher amounts if colder air arrives sooner. A second, colder system may follow late Sunday into Monday, the Weather Service and the Chronicle both said.
Bay Area residents heading to Tahoe for the weekend should treat Friday night travel as the most serious risk. The Weather Service urged anyone who must cross the Sierra to pack chains, a shovel, warm clothes, blankets, water and snacks, and to check Caltrans QuickMap and Nevada road conditions before leaving. Lower-elevation highways may see rain before the changeover to snow, the Chronicle noted, and the exact timing of that change remains uncertain.