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.