The Sierra Nevada’s snowpack is just 68% of normal after a whiplash winter, but water is moving well, experts say.

There’s still a month left, but this winter in California so far can be summed up in two words: roller coaster.

It started out so dry that Lake Tahoe ski resorts couldn’t open their regular Thanksgiving season. Then 10 snow fell on Christmas, saving the ski season and bringing totals up to historic averages. But five weeks of warm and dry weather followed. Then in mid-February snowstorms dumped another 9 feet in five days, contributing to deadly avalanche conditions.

On Thursday, the statewide snowpack of the Sierra – which provides about one-third of California’s water – stood Thursday at 68% of its historical average and is falling, at least two more weeks of dry weather forecast.

“It’s whiplash weather,” said Andrew Schwartz, lead scientist at UC Berkeley’s Central Sierra Snow Lab near Donner Summit. “We go from warm and dry to a heavy snowstorm, and dry again in a few days. It’s been chaotic.”

With dry weather forecast for the next two weeks, there is little chance of reaching 100% of normal by April 1, typically the end date for California’s snow season, Schwartz added.

“We still have a long way to go to get back on track, and there isn’t much time to do it,” he said. “The chances of major storms in the second half of March and April are not high.”

Years ago water managers in cities and farm communities across California would have been nervous. But after three consecutive wet winters leading up to this year, lakes across the region started the winter with more water than usual and are now close to full.

On Thursday all of California’s reservoirs were above their historic average. The largest, Shasta, near Redding, was 82% full, or 115% of normal; the second largest, Oroville, Butte County, was 83% full and 129% normal. San Luis, east of Gilroy, was 84% ​​full and 105% normal; and Southern California’s largest lake, Diamond Valley, in Riverside County, was 94% full and 127% of normal.

“The good news is that our dams are in good shape,” said Jeff Mount, a professor emeritus at UC Davis and senior fellow at the Public Policy Institute of California Water Center in San Francisco.

“That’s our barrier. We won’t be able to see the water limits this summer,” added Mount. “I don’t hear a lot of talk about drought. But what happens next year is important. We will dry up our ponds and hope next winter will keep them full.”

Mount and Schwartz agreed that if the Sierra Nevada’s snowpack is about half of its historic average by April 1, wildfires are likely to be a bigger problem this summer than lack of water.

“The snowpack is very important in maintaining soil moisture,” Mount said. “Except everything dries up in the front. The low snowpack is representative of an earlier and longer fire season and potentially more intense.”

In years when California has many major snowstorms, the summer wildfire season is delayed again for the simple reason that many mountains and hills are covered in snow later in the spring and early summer, and the snow does not burn.

This year, warm temperatures were a big factor.

From November to the end of January, much of the American West, and large parts of the Sierra Nevada experienced the warmest temperature since modern climate records began in 1895, about 3 to 6 degrees Fahrenheit warmer than the average from 1991 to 2020, according to data from NOAA, the National Oceanic and Atmospheric Administration.

So when storms are strong, heavy rain falls as rain instead of snow. And although none of California is facing drought conditions, according to the US Drought Monitor, the organization’s weekly report released every Thursday, all other Western states are suffering from some degree of drought, and conditions in Colorado and Utah are worse.

“We’re going to be hearing a lot about worsening water problems on the Colorado River this summer, as well as major wildfires in the Rockies and Cascades,” said Daniel Swain, a climate scientist at the University of California’s California Institute for Water Resources.

The shortage of water in the Colorado River, which flows through seven Western states and includes two large lakes, Lake Mead and Lake Powell, affects California, because the river and lakes provide water to Los Angeles and other cities in Southern California, as well as irrigation water to Imperial County. When Southern California has limited resources from the Colorado River, it puts more pressure on water to be pumped from Northern California through the Sacramento-San Joaquin River Delta, Mount noted.

Climate change appears to be playing a role in the conditions California is seeing, Swain said.

“There are clear climate links to record warming, and generally low and variable snowpack,” he said. “And little evidence linking recent “whiplashness” to record precipitation events and warming.”

In addition to the warm weather that melts the snow, the warm conditions often bring large storms and hurricanes when they occur, because more water can evaporate into storms from the Pacific Ocean. Climate research that Swain and other scientists have published in recent years says that more “climate whiplash,” with dry periods and wet storms, is likely to increase as the climate warms in the coming decades.

“I actually just got a picture from someone in South Lake Tahoe this morning who got 3-4 inches of snow last week,” Swain said. “And now it’s completely melted.”