Californians are about to hear a phrase that’s been rarely uttered during the five-year drought that’s dogged the state: atmospheric river.

A band of moisture extending from the central Pacific to the Golden State’s shores and mountains will bring rain totals measured in feet and snow totals measured in yards. While it remains to be seen if 2017 is the year that California’s drought finally becomes a thing of the past, the next week will provide at least some welcome relief.

The storms are already arriving fast and furious. As of Wednesday, ski areas up and down the Sierras have seen 3 feet or more of snow. Parts of Oregon’s Cascades have also been hammered by the first set of storms.
 


Down valley and along the coast, there have been some decent rainfall totals as well. San Francisco has received nearly an inch of rain while Modesto in the Central Valley has received about 0.4 inches. The big winner has been far Northern California where Arcata has received 1.8 inches of rain to start the month. Los Angeles, though, has remained largely dry.

Snow and rain will continue through Thursday evening. After a quick break in the clouds, the next storm will roll in just in time for the weekend. Rain is likely to reach as far south as Los Angeles this time around, but the big story will be heavy snow in the mountains and foothills.

Atmospheric river California

An atmospheric river is sending moisture streaming from the central Pacific to California.

Cold air dropping down from Canada will also help bring snow to lower elevation foothills. For ski resorts in the Sierras, that means snow totals like they haven’t seen in years. Up to 15 feet of snow could fall by the end of this storm cycle next week.

The good news will be tempered a bit by windy conditions, though. Gusts could top 100 mph on ridgetops, making mountain travel dangerous.

One thing that’s undeniable about this series of storms is its value in building mountain snowpack. Similar to years past, all regions of the Sierras have lower than normal snowpack for this time of year. The central Sierras are in the most dire state with just 65 percent of their normal snowpack for this time of year. That data is collected from automated weather stations.

Scientists who took an in-person measurement on Jan. 1 about 10 miles south of Lake Tahoe said it was the 14th lowest snowpack in 50 years of measurements. That snapshot could quickly change, though. The region is right in the bullseye of the atmospheric river so the snowpack is likely to climb closer to normal over the next few days.

Building a good snowpack is crucial for spring and summer water resources, a period when California sees precious little rain and relies on snowmelt for drinking water and irrigation purposes.

California snowpack

California snowpack is below normal for this time of year, but the series of storms currently plowing into the Golden State could help erase the deficit.

Last year saw near-average snowfall for much of the state, but a March and April warmup melted out much of that snowpack. It’s too early to predict if that will happen again this year let alone how much snow will fall for the rest of the winter.

Since the drought kicked off in 2011, Californians have hoped each winter would bring enough snow and rain to bust it. Last year brought particularly high hopes, with a super El Niño brewing in the Pacific. During El Niño years, parts of the state — particularly Southern California — tends to see increased odds of more precipitation.

After a wet December, storms petered out a bit before a flurry of stormy action in March brought the state to near average winter precipitation. Unfortunately, average doesn’t cut it in a state that’s missing a year of rainfall.

There’s been intense research interest in the role climate change has played in California’s drought. While scientists have intensely debated the precipitation side of the equation, it’s become fairly clear that increased heat driven by carbon pollution at least helped reinforce the dry conditions.

Research has shown that even though winter precipitation hasn’t changed much over the last 120 years, rising temperatures have helped make drought increasingly common. They’ve also made rain falling instead of snow more common not just in California but across the U.S.

Carbon pollution will continue to ratchet up temperatures in the future, and researchers say that’s raising the specter of megadroughts in California and across the Southwest lasting a decade or longer. So while this storm may herald the beginning of the end — or at least easement — of the current drought, California and its neighbors can expect more extreme droughts in the future.