A storm dumps snow on California’s Mammoth Lakes on 28 March.Credit: Mario Tama/Getty

Not once again! Earlier this week, California was battered by heavy rain, powerful winds and thick snow — the most up-to-date in a seemingly unending procession of powerful storms. Wild climate has afflicted the previously drought-stricken state for 3 months, resulting in devastating floods, paralysing blizzards and dozens of deaths. Information released Thursday show that the snowpack is the largest on record. Nature spoke to atmospheric and climate scientists about what’s driving the surge in wet climate and what the state could appear like in a warmer future.

A uncommon snowstorm in southern California frosted the mountains on the edge of Los Angeles on 1 March.Credit: Ringo Chiu./ZUMA Press Inc/Alamy

Why are so a lot of storms hitting California?

California’s current parade of storms is driven by atmospheric rivers — extended, narrow plumes of moist air that travel from the tropics to greater latitudes. When these ‘rivers in the sky’ sweep more than mountainous regions they condense into clouds that generate heavy rain and snow, says Allison Michaelis, an atmospheric scientist at Northern Illinois University in DeKalb.

An atmospheric river can ferry massive amounts of water vapour some discharge much more than twice as a lot water as the Amazon River1. In the western United States, atmospheric rivers contribute up to half of the region’s annual rain and snow. Because final November, 31 atmospheric rivers have hit California, much more than half of which ranged from moderate to intense, according to information from the Scripps Institution of Oceanography in La Jolla, California.

Even though back-to-back atmospheric rivers are not unheard of, they make a important effect, says Michaelis. “What may have ordinarily been a much more useful occasion could turn potentially hazardous if it comes on the heels of a further program.”

Vehicles dot floodwaters from the Tule River on 21 March, just after days of heavy rain in Corcoran, California.Credit: David Swanson/Reuters

How a lot snow is there?

In the Sierra Nevada mountain variety in eastern California, the season is the snowiest because 1952, says Andrew Schwartz, an atmospheric scientist who leads the University of California, Berkeley’s Central Sierra Snow Lab in Donner Pass. “It’s just dumping snow,” he says. A total of 18 metres of snow has fallen at the lab this season, almost double the yearly typical. And statewide, the snow’s water content material — the quantity of water that would outcome if the snow have been melted — is roughly double the typical, says Schwartz.

The circumstances have brought welcome relief just after the 3 driest years on record in California, permitting the rollback of ‘exceptional’ and ‘extreme’ drought designations for the 1st time because 2020, according to the US National Oceanic and Atmospheric Administration’s US spring outlook. But capturing and storing water released as the thick snowpack starts to melt can be a race against time, says Tom Corringham, a investigation economist at Scripps. If the snow melts as well swiftly, the excess water ends up in the ocean alternatively of becoming stored and distributed to exactly where it is necessary most, he says. “That’s not best for water management.”

Persons eliminate snow from a residential complicated in Mammoth Lakes, California, on 29 March.Credit: Mario Tama/Getty

Is climate modify playing a aspect?

As the atmosphere warms, atmospheric rivers are probably to grow to be much more frequent and hold much more moisture, and that will outcome in heavy downpours of rain and snow, says Schwartz. He notes that California is swinging involving wet and dry periods that are much more intense than in the previous. “While this variability has usually existed, it is becoming amplified due to climate modify,” he says.

Kim Reid, a climate scientist at Monash University in Melbourne, Australia, says that much more operate desires to be accomplished to have an understanding of how climate modify will impact jet streams and other systems that influence the path of atmospheric rivers. If atmospheric rivers shift by a handful of degrees latitude, they could grow to be much more popular in some regions and rarer in other individuals, she says.