The Bay Area weather forecast for Thanksgiving weekend sums up why many people live in California — sunny skies and temperatures in the 70s — even as other parts of the country, from the Great Lakes to New York , bracing for snow or digging in from recent snowstorms.
But shortly after Turkey Day and Black Friday disappeared from the rearview mirror, the first new rain and snowfall in three weeks is expected to hit Northern California on Monday.
“For Thanksgiving Day, it should be a really nice, enjoyable day,” said meteorologist Sarah McCorkle of the National Weather Service in Monterey. “We are seeing a little warm-up. Thanksgiving should be the hottest day of the week.
Take advantage, because by Monday, a low pressure system from Alaska is expected to bring a modest amount of rain, between 0.05 inches and 0.25 inches, to lower elevations around the Bay of San Francisco, with up to a half inch in the Santa Cruz and Big Sur Mountains, according to the National Weather Service.
Forecasts could still collapse. Any new moisture should continue to reduce the fire danger in the area. But don’t look for change in depleted tanks.
“It won’t be much, just enough to get things wet again,” said Jan Null, a meteorologist with Golden Gate Weather Services in Half Moon Bay. “It will disrupt traffic on Monday but will not impact the drought.”
The storm is also expected to bring 3 to 6 inches of fresh snow to the Sierra Nevada. It’s a welcome, albeit modest, boost as ski resorts have started to open in recent days for the winter season.
“That should be enough to freshen things up,” said Craig Shoemaker, a forecaster with the National Weather Service in Sacramento.
Thanksgiving week is usually the start of ski season in the Sierra, a time when Bay Area visitors pack up SUVs and head to Lake Tahoe. It was also when California water managers began to pay more attention to snow levels, which provide about a third of the state’s water supply.
Boreal Mountain Resort, in Donner Summit on I-80, opened Nov. 11. Northstar opened the next day. Palisades Tahoe, Heavenly and Kirkwood opened last week. Other stations, including Sierra-at-Tahoe, which was rebuilt after being damaged in the 2021 Caldor Fire, are scheduled to open Dec. 3.
So far, the winter snow season has started well.
After a dry October, a storm on November 1 was followed by a larger one on November 8, which brought over 1 inch of rain to parts of the Bay Area and 3 feet of snow to many parts of the Sierra.
There was still 13 inches of natural snow on the ground at the UC Central Sierra Snow Lab near Donner Summit on Wednesday, in part due to cooler than normal temperatures in recent weeks. And the 56 inches that have fallen there since October 1 is 230% of the historical average for that period. Ski resorts added to the natural accumulation of artificial snow from snow cannons.
“Our snowpack is in relatively good shape compared to the same time last year,” said Andrew Schwartz, senior scientist at UC’s snow lab.
It’s the start of the season. To end California’s severe drought by the end of the winter season in early April, the Sierra will need to receive about twice as much snowfall as the historical average, Schwartz said.
“It’s hard to say how the winter is going overall until at least February 1, but we’re hoping the big storm track will start sending us some precipitation,” he said.
As of Wednesday, 85% of California remained in severe drought, with 40% in extreme drought and 13% – mostly the San Joaquin Valley – in exceptional drought, the worst of five categories, according to the US Drought Monitor, a weekly federal report.
Last year started with a very promising trend, when atmospheric river storms flooded Northern California in October. Similar storms brought more rain and snow in December.
But then January, February and March were parched — the driest early months of any year in California’s recorded history. The season ended with the Sierra snowpack at 37% of normal on April 1 and the state still mired in drought.
Overall, the past year has been the least dry of the last three. San Francisco received 84% of its historical average precipitation from October 1, 2021 to September 30, 2022. Oakland fared better with 93%. Los Angeles was 88% of normal. San Jose trails with 58%.
But the previous two years were so dry that reservoirs and groundwater tables could not be replenished. Many of the state’s largest reservoirs are currently only half as full as their late-November historical average.
The largest, Shasta Lake near Redding, is 31% full. The second largest, Oroville in Butte County, is 28% full. Similarly, Folsom Reservoir is 26% full and San Luis, east of Gilroy, is 25% full.
California’s last drought, which began in 2012, ended in the spring of 2017 with waves of huge riverine atmospheric storms. The storms, which showed that prolonged droughts can end in a big wet year if enough rain falls to fill reservoirs, caused the Oroville Dam to nearly collapse and flood downtown San Jose. , leaving $100 million in damage in their wake.
Forecasters say they don’t know what the rest of this winter will bring. They can only accurately forecast the weather about a week out, even using powerful supercomputer models, satellites, buoys, weather balloons and other equipment.
“This time of year, any precipitation is good,” Schwartz said. “We’re happy to get anything other than hot temperatures and sunshine. Crossed fingers.”