See How One Year's Snowpack Buried the California Drought

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Mammoth Lakes, California on January 18, 2015. Right: The same location on January 14, 2017. (Images provided by Planet Labs)

It might be appropriate that California water managers designate April 1 as the date when the Sierra snowpack is presumed to be at its peak for the season. It tends to be unpredictable. But this year's bounty is no April Fool.

The water content of the Sierra Nevada snowpack currently stands at 164 percent of normal for this date (the official April 1 snow survey being held on March 30 this year, fudging for the weekend). Two years ago, it stood at 5 percent.

The difference is starkly illustrated in satellite imagery that KQED has compiled from Planet Labs, comparing three well-known parts of the Sierra this year, side-by-side with the same spots in 2015. (Use the vertical slider to compare side-by-side images.)

These three locations are shown in the satellite images below. (Teodros Hailye/KQED)

After a blitz of winter storms from late December into February, it looked like this year's snowpack might be headed for a record. NASA snow hydrologist Tom Painter says it was like taking the entire average annual flow of the Colorado River and dumping it on the Sierra in about six weeks' time. But the parade of Pacific storms has slowed to a trickle in March and California's precipitation season winds down in April.

There's another reason why this year's snow is unlikely to surpass the record year of 1983: temperature.


"Part of the difference this year is that the storms are coming in warm," says hydrologist Roger Bales, "So areas that maybe in 1983 got snow accumulation, are now getting rainfall."

Bales, who directs the Sierra Nevada Research Institute at UC Merced, sees this as part of a long-term trend.

"It's really that warmer-temperature regime that we're moving into," he says. "Our best outlooks using climate models suggest [that] as we continue to put more greenhouse gases in the atmosphere, we're going to see, on average, warmer winter temperatures."

Bales says the evidence is already on the ground, the "snow line" (elevation where it becomes cold enough for rain to turn to snow) having moved uphill "a few hundred feet" in recent decades.

"We're getting more of those warm storms where the snow line is up 8,000 or 9,000 feet in the mountains."

For the record, that 1983 snowpack was at 230 percent—more than double—the "normal" amount around April 1.

By almost any measure, however, this has been a banner year.

It was two years ago that Governor Jerry Brown stood on a barren slope near Echo Summit, using the stark backdrop to announce the first-ever statewide mandatory water restrictions.

If he decides to make a return visit today, he'd better bring snowshoes. He'd be standing on closer to 10 feet of snow.