What Winter Weather Means For California’s Drought—or Flooding in L.A.

LAMag spoke to the lead climate scientist at UC Berkeley’s monitoring project about the blizzard’s impact on the crucial Sierra Nevada snowpack

After a record-shattering weekend of heavy snowfall in Los Angeles County, and more winter weather on the way, Angelenos may be asking just what else is coming as these conditions persist and how it relates to the climate change crisis. For a sunny and temperate state, extreme weather commonly takes the form of drought or intense rainfall, with snow often occurring substantially above sea level in the Sierra Nevada mountains. 

Snowpack in the Sierra Nevada has been accumulating at a markedly pronounced rate, according to recent reporting; as of earlier this month, it stood at 193% of its historic average. It’s notable that this measurement was taken before the storms that are buffeting the Southland.

The Sierra Nevada snowpack is far from a superfluous chunk of ice. Officials at the California Department of Water Resources use it to determine the allocation of up to at least 30% of the state’s water supply. With drought across California in recent years, monitoring the snowpack is essential—increased snowfall can lead to an increase in the water supply to offset dry conditions. The possibly troublesome flip-side is that a larger Sierra Nevada snowpack also necessitates added attention to flood management, given the possibility of a sharp uptick in runoff. 

Andrew Schwartz is the lead scientist at UC Berkeley’s Central Sierra Snow Lab, located 7,000 feet above ground in the Donner Pass. The lab was founded by the U.S. Weather Bureau and the Army Corps of Engineers in the 1940s to gather crucial precipitation data on snowfall in an otherwise hot and dry state. Since the blizzard hit over the weekend, Schwartz and his team’s monitoring work has gotten rather busy. 

“If we get 15 feet over the next month, we’re going to be looking really pretty good for resolving not just short-term drought, but some of our longer-term droughts as well,” Schwartz tells LAMag. 

That’s the best-case scenario, considering that if the blizzard drifts off after this and stagnates, the increased snowpack will only be more useful for a shorter-term drought. With the persistence of the storm later into the week, it seems that an abundance of water is becoming increasingly possible. 

Of course, whether the snowpack remains frozen is key to predicting whether a more adverse event like major flooding will occur. Schwartz says that there is flood risk with these types of deep snowpack, “especially if we have any type of warm event coming on shore, like rain or snow.” Cooler temperatures in the forecast could head off the expanded snowpack melting and potentially causing flooding in Los Angeles or elsewhere. 

Climate change is always a top of mind concern amid intense and odd weather events, such as SoCal’s recent blizzard. Schwartz says to understand this storm’s full impact on the ongoing climate crisis, plenty of data collection will still need to be done. 

“For every degree of celsius that the atmosphere warms, it can hold 7 percent more water vapor,” he explains, and when intense precipitation events are followed by periods of drought, it causes what Schwartz calls the “weather whiplash” of climate change. 

“These types of massive snowfall events are definitely kind of a fingerprint of climate change,” he adds.

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