Although it’s well into spring, the snowpack in California’s mountains remains huge, measuring 254% of average in the state’s May 1 snow survey on Monday. The Sierra Nevada and southern Cascades together have seen near-record accumulation this year, with the snowpack peaking on April 8 and then beginning to decline, state records show, losing just under 20% of its water mass since. A cold start to April and lots of cloud cover prompted the snow to melt at slower-than-average pace, state officials say, leaving the snowpack in May among the largest in modern times for the month. This amount of snow presents the potential for catastrophic flooding as it melts through the rest of spring and into summer. Already, many areas of the state are on high alert, notably the southern San Joaquin Valley.

Related articles: 

• Los Angeles Times: Despite recent heat wave, most of California’s colossal snowpack has yet to melt
• Mercury News: California flooding - 80% of Sierra Nevada snowpack hasn’t melted yet
• Bay City News: CA’s snowpack boosts state’s water supply but raises concerns over flooding
• Sacramento Bee: Here is how much snow remains in the Sierra as officials plan for a big spring runoff
• Courthouse News Service: California snowpack reaches historic 240% of normal
• KCRA – Sacramento: DWR snow survey – Sierra snowpack remains more than double the average for this time of year
• Newsweek: Photos show Yosemite waterfalls from above as snow melts
• Popular Science: What California’s weird winter means for its water problems