By Raymond Zhong | Graphics by Mira Rojanasakul
Photographs by Erin Schaff/The New York Times
California, where earthquakes, droughts and wildfires have shaped life for generations, also faces the growing threat of another kind of calamity, one whose fury would be felt across the entire state.
This one will come from the sky.
According to new research, it will very likely take shape one winter in the Pacific, near Hawaii. No one knows exactly when, but from the vast expanse of tropical air around the Equator, atmospheric currents will pluck out a long tendril of water vapor and funnel it toward the West Coast.
This vapor plume will be enormous, hundreds of miles wide and more than 1,200 miles long, and seething with ferocious winds. It will be carrying so much water that if you converted it all to liquid, its flow would be about 26 times what the Mississippi River discharges into the Gulf of Mexico at any given moment.
When this torpedo of moisture reaches California, it will crash into the mountains and be forced upward. This will cool its payload of vapor and kick off weeks and waves of rain and snow.
The superstorm that Californians have long feared will have begun.
In centuries past, great rains deluged the Pacific Coast, and strong storms in recent decades have caused havoc and ruin. But, because of climate change, this one would be worse than any in living memory.
Drenching rain will pummel cities and towns.
At times, the hills around Los Angeles could get nearly two inches of rain an hour.
Heavy rain and snow in the Sierra Nevada will test dams in the Central Valley, one of the world’s most productive farm belts.
While all this has been happening, another filament of moisture-laden air will have formed over the Pacific and hurtled toward California.
After a month, nearly 16 inches of precipitation, on average, will have fallen across the state.
Large swaths of mountainous areas will have gotten much more.
Communities might be ravaged beyond resettling. None of the state’s major industries, from tech and Hollywood to farming and oil, will be untouched.
The coming superstorm — really, a rapid procession of what scientists call atmospheric rivers — will be the ultimate test of the dams, levees and bypasses California has built to impound nature’s might.
But in a state where scarcity of water has long been the central fact of existence, global warming is not only worsening droughts and wildfires. Because warmer air can hold more moisture, atmospheric rivers can carry bigger cargoes of precipitation. The infrastructure design standards, hazard maps and disaster response plans that protected California from flooding in the past might soon be out of date.