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Atmospheric Rivers Responsible for 24 Trillion Gallons of Rain Make A Comeback In California

by Joseph Trujillo-Falcón | Bilingual Meteorologist


Atmospheric River Approaches the West Coast, January 14, 2023. Source: GOES-West 

After torrential rainfall over the last couple of days, exceptional drought conditions have been completely wiped out in the state of California. A corridor of moisture in the sky, known as atmospheric rivers, has brought significant rainfall to the U.S. west coast, with flash flooding resulting in at least 19 casualties as of Saturday. According to the National Weather Service, the storm is one of the most impressive in nearly 20 years.

U.S. Drought Monitor for the State of California in December (right) and January (left). Source: USDA 

What Are Atmospheric Rivers?

How Atmospheric Rivers Form. Credit: NOAA 

Much like a river moving over land, atmospheric rivers are streams of water vapor traveling through the sky. Usually in tropical regions, warm, moist air rises and travels through atmospheric currents across the ocean. When atmospheric rivers move over land and rise farther into the atmosphere, they can cause heavy rain and snow over land. On average, about 30 to 50 percent of annual precipitation in the west coast states can be attributed to atmospheric rivers. 

Impacts Continue in California 

A series of several atmospheric rivers have produced about 24 trillion gallons of water in California since late December. Continued, intense rainfall has resulted in flash floods, mudslides, evacuations, and power outages throughout the entire state. As of Saturday, poweroutage.us has reported over 22,000 power outages statewide in California.  

Looking at the upcoming week, more rain is expected throughout the state. With the same drought-stricken areas receiving rainfall, the following rain events can result in more significant flooding events, as the ground is already saturated from previous storms. After approving an emergency declaration, President Biden is expected to sign a major disaster declaration for the state that will open more essential resources and aid for California.

Forecast for Upcoming Rain in the Next 3 Days. Source: NWS Weather Prediction Center 

A First Glimpse at the Damage 

Users on Twitter are reporting damage across California. From floods to road closures to even tornadoes, check out significant impacts: