December 31, 2022-March 25, 2023
According to NOAA, atmospheric rivers (AR) are flowing columns “of condensed water vapor in the atmosphere responsible for producing significant levels of rain and snow, especially in the Western United States” that, when powerful, can result in extreme rainfall and flooding. California experienced atmospheric rivers starting at the end of December 2022 and ending with two consecutive ARs in March 2023. These devastating weather events caused mandatory evacuations, loss of power to hundreds of thousands of businesses and homes, property damage, and loss of life. The extensive damage and threat to safety and public health caused by these storms prompted President Joseph Biden to issue an emergency declaration for the state of California that included 17 counties.
- Over 20 fatalities through January 2023 and at least five more in March 2023
- More than 1,400 rescues
- More than 700 landslides
- Damages are projected to exceed $1 billion
- Atmospheric Rivers: Background and Forecasting [February 9, 2023]
- Flooding and Federal Projects: Exposures and Limits to Liability [February 2, 2023]
- Hazard Mitigation Assistance: Mitigation Action Portfolio [October 2022]
- Progress Toward Resilient Infrastructures: Are We Falling Behind the Pace of Events and Changing Threats?
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