California Office of Emergency Management calls viral video about ‘megaflood’ misinformation

If you saw a recent viral video claiming a megaflood “coming for California” will be the worst natural disaster in world history, don’t panic.|

If you saw a recent viral video claiming a megaflood “coming for California” will be the worst natural disaster in world history, don’t panic.

The video about an “ARkStorm” is full of misinformation, according to the California Governor’s Office of Emergency Services.

In its own video, posted on YouTube Friday, a CalOES spokesperson said the video is misleading Californians about the atmospheric river expected to make landfall this week.

The misleading video has more than a half million views, CalOES said.

CalOES representative Brian (no last name given) said that while the state has a long history of flooding and is anticipating rain in the coming weeks, officials were not expecting a storm of epic proportions like the viral video mentions.

“Residents have nothing to fear as long as they take a few basic steps to be ready,” Brian said in the CalOES video.

The incoming atmospheric river may dump up to 6 inches of rain and create 50 mph wind gusts in the North Bay from Tuesday night through Wednesday, according to the National Weather Service.

About 3 to 4 inches of rain are expected in Santa Rosa and Napa, forecasters said Monday, while Sonoma County’s hills could see up to 6 inches, said Rick Canepa, a meteorologist in the weather service’s Monterey office.

Still, it’s far from the viral video’s claim of an “ARkStorm.”

Named for atmospheric river (AR) plus 1,000 (k), an ARkStorm is a “megastorm” scenario that’s projected as a one-in-1,000-year event, according to the U.S. Geological Survey. An ARkStorm is believed to be the cause of the Great Flood of 1861-1862 that created a 300-mile long, 20-plus mile wide inland sea in the Sacramento-San Joaquin valleys, the USGS said in a 2018 report.

According to a 2022 study in Science Advances, climate change is increasing the risk of megafloods in California as it contributes to the increased strength of atmospheric rivers — the long bands of moisture-laden vapor that flow toward California and produce the heaviest rain — increasing cumulative rainfall and hourly intensity, resulting in substantially more runoff and the risk of megafloods.

The Office of Emergency Services recommends residents sign up for alerts at and make a family emergency plan. Residents are also encouraged to get their weather news and emergency alerts from officials channels like

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