Was December’s Storm a Drought Buster?
December was a month for the record books when it comes to Sierra snowfall. Donner Pass saw 193.7 inches (more than 16 feet) of snow pile up in the final month of 2021, breaking the previous record of 179 inches set back in 1970 (UC Berkeley Central Sierra Snow Lab).
In fact, the California Department of Water Resources says that, state-wide, the snow water equivalent of all that snowfall was 160% of the average for this time of year. While that number certainly sounds impressive, it’s important to keep in mind that the snowpack (which provides about a third of the state’s water supply) is only about half of what we need for the entire rain and snow season.
It may be tempting to think that December’s snowstorm signals an end to the state’s two-year drought, but as we’ve learned, a stretch of wintery precipitation just chips away at California’s drought conditions. In reality, more snow is needed to prepare the state’s water supply to carry us through the drier months.
Right now, the Shasta and Oroville Reservoirs are only at about 34% and 44% capacity, respectively. So, even with the storms we had at the end of last year, both reservoirs need to have much more water in them by the time summer rolls around to combat drought conditions.
If they are above 80-90% capacity by May, we can be hopeful that we are making significant strides towards having enough water storage to mitigate, manage, and balance our water needs with our regular summer drought for 2022. But if the dry conditions seen in January persist through winter and spring, we could end up with reservoirs remaining below storage capacity as we enter the warmer summer months.
A dry January
So far, 2022 is off to a very dry start. After the record-breaking snowfall that accompanied December, the state has received very little (if any) rain or snowfall this year. The lack of accumulation was especially apparent in the Sierras, where the ground is largely devoid of snow below 6,000 feet. So, does this mean we should start worrying that California’s two-year drought might turn into a three-year drought?
Dry spells occurring in the middle of winter are actually quite common. The key factor that could determine whether or not we are heading into another year of drought is the length of the dry spell. Going as far back as 1950, there’s been a dry stretch of around 19 days in nearly every winter season (usually in either December or January). According to Jan Null (a meteorologist with Golden Gate Weather Services in Half Moon Bay): “It’s not unusual for us to have dry periods in December and January. It’s the rule rather than the exception”.
That being said, the state-wide forecast is calling for more dry, sunny weather over the next two weeks driven by a large and persistent high-pressure ridge spanning much of the west coast. As Null points out, another two weeks of sunny weather would put the dry streak at 28 days, which would make this dry spell the 11th driest in the past 71 winters. The lack of rain and snowfall in January has resulted in returning our record-breaking rainfall and snowpack numbers back to being much closer to their historical averages.
According to the National Weather Service, Sacramento, on January 1st (just after December’s snowstorm), the Sierra Nevada snowpack was 168% of normal for that time of year. As of Sunday, January 23rd, the snow water content for Northern Sierra was down to 113% of average to date, Central Sierra was at about 109%, and, state-wide, we were at 111% of average for this time of year (NWS Sacramento).
Translating the data
So, what does this all mean? Did December’s storm bring enough rain and snow to help alleviate California’s drought conditions? Is this dry, warm January a sign of what’s to come for the rest of the winter season? Unfortunately, there’s really no clear answer to either of these questions. According to Jeanine Jones, drought manager for the California Department of Water Resources in Sacramento: “We simply don’t know what the rest of the water year is going to be like”. While we are certainly better off than we were in mid-December, the weather over the next few months will be critical for our water storage.
And the long-range forecasting by NOAA, done in three-month blocks, is inconclusive and predicts an equal chance of slightly above and slightly below average precipitation through April. But as we move into spring, the chance of below average precipitation increases.
Addressing these impacts through meadow restoration
The uncertainty about future precipitation is one of the many reasons why meadow restoration is so important. As winter snow melts, the soil of mountain meadows holds the moisture like a sponge and then releases it slowly. This helps minimize downstream flooding during the spring. Meadows release water over a long period of time, which helps stretch and extend valuable water supplies throughout the long, dry summer months.
Headwater meadows of the Yuba Watershed have been historically reliant on snow but will become increasingly important as the High Sierra begins to receive a higher amount of precipitation in the form of rain (as opposed to snow). These invaluable ecosystems are able to reduce the erosive potential of heavy rain events, storing more water as groundwater and delaying peak season flows later into the summer. SYRCL’s work to restore high elevation meadows such as Van Norden Meadow aims to support resilient meadow ecosystems in the face of climate change.
At the end of the day, we just don’t know what kind of weather will accompany the remainder of our winter season. That’s why it’s imperative we work to protect and restore the meadows that play such a crucial role in storing and filtering our groundwater.
For more information about precipitation, snow water, and reservoir storage, please visit the USDA’s Natural Resources Conservation Service.
To learn more about SYRCL’s meadow restoration projects, click here.