Picture this: you’re sipping your morning coffee in Sacramento when suddenly the news alerts start pinging on your phone. Another atmospheric river is barreling toward California. Roads are closing, evacuation warnings are issued, and you can’t help but wonder – didn’t this just happen a few months ago?
You’re not imagining it. These so-called “rivers in the sky” have been pummeling the Golden State with increasing fury, turning neighborhoods into swimming pools and making headlines worldwide. From the catastrophic Oroville Dam crisis to billion-dollar damages across Los Angeles, atmospheric rivers are rewriting California’s flood story in ways that would make even seasoned meteorologists nervous.
The Invisible Giants Above Our Heads
Think of atmospheric rivers as invisible highways of water vapor stretching thousands of miles across the Pacific Ocean. They are narrow bands of water vapor that wind sinuously through the atmosphere, like a river; they can transport vast quantities of water across the ocean, generally from the warm tropics toward the cooler midlatitudes, like California. At their strongest, these systems can carry up to 15 times the amount of water flowing out of the Mississippi River.
The most famous type is the “Pineapple Express,” which sounds like something you’d order at a tropical smoothie bar. One common flavor of AR, explains Christine Shields, an atmospheric scientist at the National Center for Atmospheric Research, is the colloquially termed “Pineapple Express.” Those ARs originate in the tropics near Hawaii and “essentially just move water from lower latitude to a higher latitude, like a river on Earth,” she says. These atmospheric conveyor belts can stretch up to 1,000 miles long and 300 miles wide, carrying enough moisture to rival the Amazon River itself.
Nature’s Double-Edged Sword
Here’s where things get tricky – atmospheric rivers aren’t inherently villains. Atmospheric rivers provide roughly half of California’s annual precipitation, restoring the state’s snowpack and filling reservoirs, but the storms can also cause significant damage, especially when they arrive in groups. Without them, California would be a desert, and your avocados would cost even more than they already do…