‘Bomb Cylone’ Dumps Historic Rain on California, Brings Flooding and Landslide Risks

A minivan sits stranded on a flooded street in California.

A Category 5 “bomb cyclone” dumped historic amounts of precipitation across much of Northern California Sunday, creating dangerous flooding and landslide conditions in the region scarred by recent wildfires.

The “atmospheric river” dumped more than 5.35 inches of rain on Sacramento on Sunday, the most in a 24-hour period since record keeping began during the Rutherford B. Hayes administration (1877). Other locations at higher elevations were expected to see even more precipitation, and as much as 2 feet of snow were expected in the Sierra Nevada.

Flooding was reported across the Bay Area. Climate change, caused by the extraction and combustion of fossil fuels, not only worsens extreme precipitation events by increasing the amount of moisture the atmosphere can hold, it also worsens the risks of landslides in areas incinerated by climate-supercharged wildfires.

State police closed a stretch of State Route 70 in two counties after multiple landslides in the Dixie Fire burn scar, and the NWS issued flash flood warnings for both Dixie and Caldor Fire burn scars. Numerous locations across the state were under evacuation orders because of the potential for mudslides in fire scars.

“If you are in the vicinity of a recent burn scar and haven’t already, prepare now for likely debris flows,” the Sacramento weather service tweeted. “If you are told to evacuate by local officials, or you feel threatened, do not hesitate to do so. If it is too late to evacuate, get to higher ground.”

The historic rainfall will not undo the massive drought, made more severe by climate change, the state faces. “Even with 5 inches of rain in Sacramento, our deficits are immense,” Jeffrey Mount, a geologist and water expert at the Public Policy Institute of California told the Sacramento Bee. “We’re basically missing two years of ‘precip’ in this basin. It’s not a drought buster.”

For a deeper dive:

Precipitation so far: The Sacramento Bee, AP, The Sacramento Bee, CBS, NBC, The Washington Post (video), San Francisco Chronicle; Landslides: San Francisco Chronicle; Atmospheric River: Axios, The Washington Post, The New York Times, The Hill, AP; Drought: The Sacramento Bee; Climate Signals background: Extreme precipitation increase; 2021 Western wildfire season; Drought

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