The latest atmospheric river to lash California has unleashed more historic rainfall, heavy snow and flash flooding across the state — as forecasters warn the worst was yet to come on Wednesday.
The big picture: An estimated 27,000 people were under evacuation orders and thousands more were affected by evacuation warnings amid flooding and landslide concerns. Dozens of flood watches, warnings and advisories were issued across the Golden State.
- The National Weather Service said the "potent storm" that ramped up Tuesday was "expected to produce heavy mountain snow and gusty winds from the Sierra to the central/northern Rockies" through Wednesday.
- This atmospheric river is at least the 11th to hit California since December and follows on the heels of the one that struck the state from Friday and into the weekend — and many of those areas are getting soaked again.
Threat level: Heavy precipitation was expected to continue over Tuesday night, particularly for Southern California coasts and the south Sierra Nevada, where heavy snow was projected above 8,000 feet, per the NWS Weather Prediction Center.
- The NWS warned of potentially "catastrophic" flooding from this storm.
- Heavy rain combined with snowmelt in areas below 5,000 feet was projected to cause widespread flooding Wednesday.
- Residents in the Los Angeles area were warned about roadway flooding and rock and mudslides.
By the numbers: The NWS' L.A. office reported preliminary data showing longstanding rainfall records had been smashed at airports in Santa Barbara (2.13 inches), Los Angeles (0.61"), Santa Maria (1.29") and Paso Robles (0.9").
- Nearly 237,000 customers were without power in California late Tuesday local time — mainly in the Bay Area, per Poweroutage.us.
State of play: Schools and roads were closed across California.
- The Sacramento, Salinas, and Merced rivers were among those to overflow as the storm swept south.
- Forecasters warned the heaviest rain was expected over the northern Sierra Nevada, where the Shasta County Sheriff's Office said an evacuation order was issued on Tuesday evening "due to heavy flooding."
- In San Francisco, officials said powerful winds broke two windows in a high rise as heavy rain came down. There were no immediate reports of injuries.
Meanwhile, the southern Sierra Nevada appears to have recorded its largest-ever snowpack — more than 260% above its seasonal average, according to the California Department of Water Resources.
- The U.C. Berkeley Central Sierra Snow Lab reported Tuesday morning that another 13.6 inches of snow had fallen "and that takes us to within 7" of the winter 1982/1983 total, which is currently second snowiest all-time" on record at the central Sierra snow laboratory.
- The "way that we get down into the lab right now is by going down into this big chasm of snow," the lab noted in a tweet.
Context: Atmospheric rivers are narrow highways of moisture that can travel thousands of miles, from the tropics to mid-and-northern latitudes.
- Studies show climate change is intensifying these events as warmer air carries additional water vapor and also yielding sharper swings between precipitation feasts and famine in California, per Axios' Andrew Freedman.
Editor's note: This article has been updated with additional details throughout.
