Excerpt:
The same weather that replenishes California water supplies could bring the next megaflood.
A procession of storms is drenching Northern California this week, with rainfall already topping 2 inches in San Francisco and surpassing 8 inches in the Santa Cruz Mountains. More precipitation is on tap through the weekend, prompting concerns of widespread urban flooding and potential landslides.
The downpours are fueled by an atmospheric river, a band of moisture that can flow for thousands of miles, in this case from the tropical Pacific, near Hawaii, all the way to the West Coast. Even though you can’t see them, these rivers in the sky transport colossal amounts of water around the planet.
“An average atmospheric river instantaneously carries two to three times what the Amazon River typically carries,” said Alexander Gershunov, a research meteorologist at UC San Diego’s Scripps Institution of Oceanography.
When that moisture falls as rain, it can have devastating consequences. Scientists believe that a series of atmospheric rivers caused the Great Flood of 1862, a megaflood that left 6,000 square miles of California’s Central Valley underwater. Atmospheric rivers cause about $1.1 billion in flood damage annually across the western United States.
But atmospheric rivers also provide important benefits…
