Look What the Big Storm Brought to the Sierra

A satellite view of South Lake Tahoe February 18, 2018 (left) and March 4, 2018 (right).  (Teodros Hailye/KQED/Images by Planet Labs)

A powerful storm visible in satellite images has dramatically changed the state's seasonal snowpack totals, according to today's monthly survey --  but it still leaves California's water supplies well below normal.

The Sierra Nevada's biggest storm of the year attracted (and threatened) skiiers and closed some roads; Squaw Valley and Alpine Meadows reported 7 feet of snow this weekend. The storm also delayed state scientists' monthly trek out to Phillips Station, just off highway 50 near Echo Summit. This is just one spot in the California Cooperative Snow Survey (CCSS) managed by the Department of Water Resources (DWR).

On Monday, survey chief, Frank Gehrke, found 41.5 inches of snow at the site, with a water content of just over nine inches. That's more than triple what the site held a week earlier.



"It's an encouraging start to March, but we've got a long way to go," Gehrke said.

Measurements from the larger network of stations comprising the CCSS find the state’s snowpack at around 37% of normal for this time of year. That's a potential problem since the frozen reservoir of water in California's snowpack has, in the past, provided around a third of the state’s supplies.

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"It would take two more of the sort of storms we just went through" to approach normal snowpack by April 1, Gehrke said.

California officials ended the state declaration of drought in 2017, buoyed by last year’s near-record winter rains. But paltry winter precipitation has returned nearly half the state to drought again, according to the U.S. Drought Monitor.

So much snow dumped in the last few days that the Sierra Avalanche Center is warning of considerable risk. And recent rainstorms have filled reservoirs to capacity or close to it even in overdry Southern California. Those conditions have helped stave off a return to declared drought in California.

UCLA climatologist Dan Swain points out that changing climatic conditions may force change in policy considerations, too. Historically, California has swung between lean water years and fat ones, between warm years and cold. However, he says, “we’re definitely drifting in a certain temperature right now, which is warmer.”



What that means, Swain says, is that California is likely to see two conditions thought to be contradictory: more rain years as well as more severe and prolonged droughts.

"These systems that we have in place right now were designed for a particular climate that no longer exists," Swain says, "and will be even further from the climate we’re likely to have just a couple of decades from now,."

DWR's Gehrke says the survey offers a simpler and immediate lesson: "Watch how you use water."