Plentiful early-season Sierra snowpack signals ‘remarkable turnaround’ amid historic drought

A series of record-setting blizzards in recent weeks that buried roads, snarled holiday traffic and even temporarily shut down ski resorts have combined to offer California a glimpse of hope after two years of historic and punishing drought.

Snowpack across the Sierra Nevada appears far ahead of historical averages — an unexpected respite from years of bone-dry forecasts, leaving climatologists cautiously optimistic about drought conditions improving across the state.

Plunging a massive pole into the snow-covered landscape along U.S. 50 near Echo Summit, officials with the California Department of Water Resources on Thursday measured 78.5 inches of snow and about 20 inches of water within that snow – a total that’s 202% of average for this time of year.

That’s about 82% of the way to what water managers would expect that location to receive by April 1.

Thursday’s largely symbolic snow measurement aligns with readings from about 100 electronic sensors across the state, which show Mother Nature finally appearing to restock the state’s water coolers.

The statewide snowpack measured 160% of its historical average for Dec. 30 – a bountiful total that, a few weeks ago, appeared all but impossible. Almost all of that snow fell after Dec. 8, when the state’s snowpack levels sat at a paltry 15% of historical averages.

“Those are really good numbers for this time of year, especially given how the season started, and especially given recent years,” said Daniel Swain, a climate scientist at UCLA and the Nature Conservancy. “In fact, it’s actually a remarkable turnaround relative to the extreme snow drought across the entire American West.”

The snowpack was aided by several recent storms that left Bay Area holiday travelers stranded at Tahoe-area ski resorts earlier this week while CalTrans crews worked 24-hour shifts to clear mountain highways of several feet of snow. Countless drought-weakened trees buckled under strong winds and thick, wet snowfall.

More than 75 miles of Interstate 80 were closed for several days, along with nearly every other highway connecting the Tahoe area with Sacramento and the Bay Area.

Thursday’s snow-measuring event, held next door to the shuttered Sierra-at-Tahoe ski resort, offered a study in extremes — conducted amid a wintry wonderland, yet set a mere two miles from a ski resort ravaged by flames last summer amid one of the state’s worst fire seasons on record.

And it came as drought conditions finally appeared to be easing across California. Weeks of snow and rain have helped push the state almost completely out of the “exceptional” drought category. The portion of the state still in extreme drought also shrank from nearly 80% to 33%.

Still, nearly the entire state remains mired in severe drought; it will take sustained precipitation over the next few months for the state to finally get back to normal, experts said.

The state’s reservoirs also need more help.

Shasta, Trinity and San Luis reservoirs remain at half their historical average for this time of year, while Oroville Reservoir is only three-quarters of the way to where it should be this time of year.

“It’s a great way to start the season,” said Andrew Schwartz, station manager and lead scientist at UC Berkeley’s Central Sierra Snow Lab. “But we haven’t been able to determine yet whether or not it’s really going to have any impacts on the drought, or even fire danger.”

The powder appears fairly well distributed across the Sierra, with the northern part of the state at 145% of average snowfall, and the central and southern portions of California at 164% and 173% of average, respectively.

It’s all thanks to a surprise atmospheric shift over the Pacific Ocean that ran counter to forecasts for a dry winter. Still, that unexpected shift could easily reverse itself in the coming months and once again leave California aching for water, climatologists and water storage experts said.

“I’d say that this is a very, very promising to this water year,” said Jay Lund, professor of civil and environmental engineering at UC Davis. “But we’re still in the first half of the water year. This is California – it could decide to get dry.”

The atmospheric forces at work above the suddenly-snowy Sierra are the same ones causing record-setting heat in Alaska, snow in the Pacific Northwest and heat waves across the Midwest and East Coast.

A ridge of high pressure parked over the Pacific Ocean has funneled storms into northern California at a ferocious rate, Swain said.

The location of that high pressure ridge has been key. It unexpectedly moved just a few hundred miles west of where forecasters originally expected it to be this winter – a razor-thin change that has made all the difference for California.

Had it been where meteorologists initially feared, the state would still be bone-dry and with little hope for relief from the drought.

“So if this pattern were to shift a few hundred miles to the east, California would dramatically dry out and warm up,” Swain said. “In fact, that was the expectation that might happen for much of this winter.

“And that could still happen in the back half of winter, if this thing shifts just by a few hundred miles further east. But up to this point, we’ve gotten really lucky.”

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