It was a white Christmas indeed as record snowfall blanketed the Sierra Nevada over the weekend, providing much-needed insurance to the depleted California snowpack.
California typically receives 90% of its rain and snowfall between early October and late April, which sets the stage for how water supplies will be balanced in the year ahead. The amount of water California receives from the snowpack is imperative in meeting the diverse water needs of unique regions found throughout the state — especially in the summer and fall — for everything from farming to drinking.
At the beginning of December, the statewide snowpack sat at just 19% of normal for the date following two straight years of drought conditions. December has provided relief, however, with wet conditions which first began with storms two weeks ago. Following the mid-month rainfall, the snowpack jumped from 19% to 76% of normal for the date according to the Department of Water Resources.
Following this weekend’s wild weather, the statewide snowpack now sits at 159% of normal for the date. The Central Sierra snowpack is now 166% of normal, and it’s been a wet few months for the San Joaquin Hydrologic Region, which includes the Tuolumne River Watershed and Don Pedro Reservoir. Since Oct. 1, DWR says the region has received 173% of normal precipitation. Don Pedro now sits at 53% capacity and 78% of the reservoir’s historical average.
Donner Pass in the Sierra received a record-breaking amount of snow, with UC Berkeley’s Central Sierra Snow Laboratory tweeting they received 38.9 inches of snow in just 24 hours. That helped smash the previous December record of 179 inches, set in 1970, with a total of 193.7 inches — and more on the way. DWR's first snow survey is set for Dec. 30, which will reveal the month's totals.
Despite the wet weather, California is still under the influence of La Niña — temporary climatic conditions that can contribute to weather that is drier than normal. In a La Niña winter, the storm track tends to hit the Pacific Northwest with heavier rain and flooding, sometimes dipping into Northern California. The southwest, meanwhile, usually receives less rainfall than normal.
As of most recent data from Dec. 23 prior to the weekend’s storms, 100% of California is still in some state of drought, though there have been improvements. Just over 23% of the state is classified as being in exceptional drought, down from nearly 46% three months ago. Data from the same date also shows that 94.78% of Stanislaus County is experiencing exceptional drought.