Karla Nemeth, the director of the California Department of Water Resources, the agency that manages the Golden State’s most precious resource, said that California must toe a fine line during intense winter storms. On one hand, the state desperately needs winter rain and snow to replenish water supplies before the annual dry spell that often persists from spring through fall.
But climate change has also intensified weather extremes in the West, and long bouts of heavy rain can cause devastating flooding or mudslides in areas that have recently burned. Warm storms in particular could melt snow prematurely and send a torrent of water down mountains and into already saturated cities.
“This is kind of a Goldilocks situation,” Ms. Nemeth said. “We’re cautiously optimistic.”
On California’s ski slopes, the unusually heavy snowfall was a welcome gift. Mammoth Mountain, a resort on the border of Yosemite National Park, expected to see several feet of snow on Saturday, with more snowfall expected through mid-January, said Lauren Burke, the resort’s director of communications.
The resort had already benefited from heavy snowfall this winter, including 10 to 15 feet of snow in the past month alone, Ms. Burke said. By midday Saturday, the resort was recording 90 to 131 inches of snow at its base depth, among the deepest in the country, according to data from On The Snow, which tracks snow cover at resorts nationwide.
“The snowpack holds up really well, even with this warmer, wet, heavy snow,” Ms. Burke said. “It just kind of slathers the mountain and builds up a really deep base.”
Significant snowpack has accumulated across the Sierra Nevada region, including, in the Southern Sierra, nearly 200 percent of the average snow water equivalent that is typically recorded at this time of year, according to data from the California Department of Water Resources.
While cautioning against the risk of flooding, experts say the storms are on track to be largely beneficial to the state. That’s in part because the water levels of the West’s major rivers and reservoirs are already so much lower than normal, so it would take an extraordinary amount of rain over a short period of time to fill them back up; the worst flooding takes place when big waterways and reservoirs spill over their banks in populated areas.