By Andrew Schwartz
For the first time in its 73-year existence, UC Berkeley’s Central Sierra Snow Lab in December 2019 was without a single full-time employee. The previous manager had retired, Berkeley was considering eliminating its funding, and the Covid-19 pandemic was preventing the hire of a new manager. By January 2021, the hard work of the lab’s director, professor Rob Rhew, had saved the lab and I was appointed as the new manager to lead it into the future. There was, however, a catch that complicated my transition to the new lead of the lab’s daily operations: I was living in Australia.
Very few people, if anyone, identify Australia when thinking about snowy locations around the world. Yet, there I was, in subtropical Queensland in the middle of the January summer heat finishing my Ph.D. research on the effects of bushfires (wildfires) on snowpack processes in Australia’s Snowy Mountains. My recent appointment at the Central Sierra Snow Lab was both distracting me from my thesis and motivating me to finish it, as I was excited to get back to the U.S. and begin my work at the lab.
Despite working in winter weather research at the National Center of Atmospheric Research in Boulder, Colorado early in my career, I hadn’t heard of the snow lab until I saw the station manager position description listed online. As such, much of my time following my appointment was spent reading about the lab in news articles and textbooks rather than working on my Ph.D. It was fascinating to see the wide range in the amount of snowfall that the snow lab received from year to year, some years, like 2015, receiving only 11 feet of snow and others, like 2011, receiving huge amounts of 54 feet. It was certainly exciting to see a place with so much snow after I’d spent the previous three and a half years working in Australia, where it would measure only a few feet deep.
Oddly, my pandemic-era international move was uneventful and the transition from studying snow in Australia to studying snow in California was relatively easy because both locations share several characteristics: They increasingly experience extreme drought, large bushfires that impact the snowpack, and rain-on-snow events. It’s no surprise that these types of events are being focused on in both locations with the large impacts that they can cause to the snowpack and subsequent water resources.
The severe drought that we currently face in California has been mirrored by similar recent droughts in Australia, where entire towns have needed water to be trucked in for showers and potable water supplies. These severe droughts underscore the importance of regular seasonal snowpack in the mountains, which generate as much as 30% of California’s annual freshwater. They also demonstrate well how difficult it can be to resolve drought conditions after they persist for extended periods of time. Lower than average precipitation, high temperatures, and increased winds can keep the landscape dry and remove moisture from the soil so that once precipitation does fall again, most of it replenishes the moisture in the soil rather than running off into streams that replenish reservoirs. Hot and windy conditions that increase evaporation in reservoirs can also contribute to significant increases in fire danger throughout California.
To date in 2021, California has had nearly 2.5 million acres burned in wildfires with many of the areas burned coinciding with alpine and subalpine areas where seasonal snowpack regularly exists; the Caldor and Dixie fires are perfect examples of these areas. These fires rapidly affected large swaths of land by removing or altering forest canopy, leaving charred tree trunks, and changing soil characteristics. As a result, snowpack processes within these areas are likely to change with less canopy allowing more sunlight to reach the snowpack, burned debris from the tree trunks falling on the snow surface and possibly increasing melt, and new soil properties that will change the way meltwater from the snowpack affects streamflows.
The atmospheric river event that impacted the Sierra Nevada on Oct. 24 and 25 brought much needed moisture to help quell drought and wildfire conditions. However, it also brought an event to the Central Sierra Snow Lab of the type that has been increasing in frequency over the past few decades and isn’t as positive as the other effects: rain-on-snow. With 10 inches of fresh snow measured on Oct. 18, and additional snowfall over the subsequent days with the occasional 1 to 2 inches falling, there was plenty of the white fluffy stuff on the ground at the beginning of the atmospheric river event on the 24th. Unfortunately, what happened next highlights the impacts these events have on our mountain snowpack and its ability to store water well into the spring and summer. Once the rain began, the snow melted quickly. So quickly, in fact, that parts of the snow lab had developed streams of melting snow where none had previously existed.
Melting of the snowpack from rain-on-snow events isn’t a new concept, but it is increasing under climate change. Not only can these events cause flooding from large and often fast releases of water, but they quickly reduce snowpack depth. Depth that is critical to continued storage and slow release of meltwater in the late season when it can help keep fire danger low and produce continued streamflows and reservoir inflows, which can prevent or resolve drought conditions.
The Central Sierra Snow Lab was initially developed by the Army Corps of Engineers and Weather Bureau with the “purpose of solving hydrologic problems in the western U.S.” and that purpose continues today. Not only is the snow lab continuing its rich history maintaining some of the longest measurements in the world that date as far back as 1879, but I have made it a focus to address the problems that we are facing in the 21st century — the same problems that I focused on with my research in Australia: drought, fire, and rain-on-snow.
Of course, the atmospheric river experienced in October at the lab wasn’t all rain-on-snow and bad news. After the rain ended, the snow started, and we received 33 inches over two days. Those three-plus feet contributed to the second highest snowfall amounts in October since the records began at the lab (48 inches) in 1970 with only October 2004 having more snow (50 inches). It will take a lot of extra snow to bring us out of the severe drought that the western U.S. is facing, and it’s not clear whether we will get precipitation needed for that to happen. One thing is certain, however: The Central Sierra Snow Lab will be continuing the wonderful work that it has done in the past while embracing new and exciting research that addresses big concerns of the future.
Many exciting new initiatives have begun since I stepped into my new role in April. Not only have we nearly broken a snowfall record, but for the first time in the lab’s history, the data collected here onsite can be directly accessed by the public on our new website: cssl.berkley.edu. In addition, we have begun construction on a new instrumentation tower, which will be finished in summer 2022 and will streamline the lab’s ability to provide timely data to partners and the public. Overall, it’s been an exciting start to my career here at the Central Sierra Snow Lab and I’m excited to bring a new era of research and continue the work of the lab’s outstanding historic past.