California's Sierra Nevada Snowpack Is Larger Than Previous 4 Years Combined, NASA Says

Brian Donegan
Published: April 20, 2017

The snowpack in California's Tuolumne River Basin in the Sierra Nevada is currently larger than the previous four years combined, according to new NASA data.

The 2017 California snowpack is near the largest on record, NASA's data showed. Airborne Snow Observatory (ASO) mapping showed the Tuolumne Basin's snowpack is twice as large as last year's and 21 times the volume of 2015, which was the lowest on record.

The combined April 1 snow-water equivalent from 2013-2016 adds up to only 92 percent of this year's April 1 measurement, NASA added.

(MORE: California's Northern Sierra Nevada Surpasses All-Time Wettest 'Water Year')

Snow-water equivalent – the water content of snow – in California's Tuolumne River Basin in 2015 and 2017. Lighter blue indicates less snow, while darker blue indicates more snow. The 2017 snow-water equivalent was 21 times greater than 2015, which was the lowest snowpack on record.

NASA's ASO measured the Tuolumne Basin's snowpack at 1.2 million-acre feet on April 1 – enough snow to fill the Rose Bowl in Pasadena, California, almost 1,600 times.

The melted snowpack from this region is a major supplier of water for California's Central Valley and the Bay Area, including San Francisco.

(MORE: The Most Billion-Dollar Weather Disasters on Record for a First Quarter)​​​​

NASA said the ASO, which became operational in 2013, is the only program that measures snow depth, snow-water equivalent and the amount of sunlight snow reflects over an entire basin, using two scientific instruments – a scanning lidar and an imaging spectrometer – on a King Air aircraft. In addition to California, it's used in Colorado, Oregon, Nevada and Idaho.

Prior to the ASO program, errors in forecasting the total Sierra snowmelt-season runoff were frequently higher than 20 percent and occasionally higher than 40 percent, NASA reported. "Now, errors in forecasting runoff from basins that ASO monitors have dropped to less than 2 percent."

(MORE: 7 Interesting Things We've Seen With the Weather So Far in April)

One ski resort in California's northern Sierra Nevada is closing in on 800 inches of snow this season. Through Tuesday, Sugar Bowl Resort measured 782 inches of total snowfall for the 2016-17 season. This is 282 inches above Sugar Bowl's seasonal average of 500 inches.

The resort tweeted Tuesday that the ski season has been extended through May 7 due to the plethora of snow.

Other resorts in the region have also measured at least 700 inches of seasonal snow through Tuesday, including Mt. Rose (761 inches), Boreal (747 inches), Northstar (708 inches) and webcams/squaw-valley-snowfall-tracker" target="_blank">Squaw Valley (705 inches). The Squaw Valley total is webcams/squaw-valley-snowfall-tracker" target="_blank">255 inches above average and nearly as much snowfall as it received the past two winters combined (718 inches).

(MORE: Where Winter 2016-17 Ranked)

"I'm actually considering staying open through the summer and fall so it becomes the 16-17-18 season," Squaw Valley CEO Andy Wirth said in an interview with Truckee Tahoe Radio KTKE, as reported by the Sacramento Bee.

This season has brought the second-most snowfall ever recorded at Squaw Valley, trailing only the 2010-11 season when it received 810 inches, according to a news release from the ski resort.

We know these numbers seem high, but they're nowhere near the seasonal snowfall record for the United States of 1,140 inches, set during the 1998-99 snow season at Mount Baker Ski Area in Washington state, located 4,200 feet above sea level.

(MORE: The Heaviest Snowfall Records in the U.S.)

For comparison, the snowfall at Squaw Valley is measured at webcams/squaw-valley-snowfall-tracker" target="_blank">about 8,000 feet above sea level – nearly double the elevation of Mount Baker.

MORE: Storms Hit California – February 2017

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