16 Million Californians Under Flood Watch As Yet Another ‘Atmospheric River’ Looms

Topline

More than 16 million residents in California are under flood watches, as forecasters warn yet another heavy band of rain called an “atmospheric river” could cause widespread flooding in northern and central California this week, following a season of heavy rain and record snow in a state that had previously struggled with severe droughts.

Key Facts

Flood watches and wind advisories are in effect throughout the majority of northern California, with flood watches stretching south of Bakersfield, while winter storm warnings are in effect in the Sierra Nevadas, according to the National Weather Service.

Forecasters with the NWS predict the atmospheric river—a long and narrow storm system that can carry tremendous amounts of rain—will unleash heavy rainfall starting Thursday and continuing through Saturday, with potential “excessive rainfall” totaling five inches or more in some areas.

Forecasters also warn snowmelt caused by heavy rain at higher elevations—which have already received near-record snowfall this year—will increase flood risks in lower elevations, including the western foothills of the Sierra Nevadas, which the NWS Weather Prediction Center warns is the “most vulnerable to flooding from rain and snowmelt.”

Big Number

More than 50 feet. That’s how much snow the University of California Berkeley’s Central Sierra Snow Lab has recorded in the Sierra Nevadas so far this year, making 2023 the fifth snowiest year on record. The snow lab had tallied 580.12 inches of snow since the beginning of October as of Monday, plus another 12 inches of snow that fell Tuesday and Wednesday—making this winter season the snowiest since at least 1970, when the lab started taking snowfall data.

Surprising Fact

Some residents of San Bernardino County, in southern California, had been trapped in their homes this week after back-to-back storms slammed the region with more than 100 inches of snow in some areas, CNN and the Los Angeles Times reported. San Bernardino County was one of 13 counties under a state of emergency last week, as more than 70,000 homes and businesses were without power across the state (more than 20,000 remain without power, according to poweroutage.us). Intense snowfall also forced officials at Yosemite National Park to close the site through Sunday after some parts of the region received nearly 15 feet of snow.

Key Background

Several atmospheric rivers caused widespread flooding and power outages in northern and southern California earlier this year. Heavy snowfall over the past month pushed parts of California out of drought, while areas in the Central Valley and Los Angeles region that had been in severe droughts were downgraded to “abnormally dry” conditions, according to the U.S. Drought Monitor. It’s unclear whether continued storms will bring more of the state out of drought, as it faces a 22-year “megadrought” affecting the southwestern U.S. AccuWeather meteorologist Bernie Rayno said the pattern of storms “hasn’t only put a dent in the drought” but will “eliminate it by the time spring evolves into summer.” Central Sierra Snow Lab scientist Andrew Schwartz, however, warned an anticipated “prolonged dry and warm period” this spring could leave California in a less “favorable” position later this year.

Further Reading

‘A Shameful Situation’: Angry mountain residents trapped by snow ask why help took so long (Los Angeles Times)

Parts Of California Out Of Drought—But Experts Still Warn Drought Conditions Will Remain (Forbes)

What Is An Atmospheric River? Here’s Why California Is Getting Hammered With Them (Forbes)