- Summary Points
- Atmospheric rivers bring heavy rain and snow to California, potentially causing flash flooding and landslides.
- Current water levels in California are below average, with major reservoirs and snowpack levels needing replenishment.
- Climate change is expected to increase the size and frequency of atmospheric rivers, leading to more severe impacts.
California is currently experiencing the effects of atmospheric rivers, large airborne currents that transport dense moisture from the Pacific Ocean and result in heavy rain and snow over land. These weather systems are crucial for replenishing water supplies in the region, especially in the context of California’s ongoing water scarcity issues.
As of now, California’s precipitation levels since October have been below average, at about 82% of the historic average. Major reservoir levels are slightly above average, but snowpack across the state is only at 32% of its usual level, with significant variations across different regions. The snowpack in the Sierra Nevada mountains, a critical source of water, is notably below average.
Atmospheric rivers are fairly common, with about 11 existing globally at any given time. While they often bring beneficial rain or snow, their size and capacity—carrying up to 15 times the volume of the Mississippi River—can lead to hazardous conditions like flash flooding, landslides, and white-out snow conditions. Last winter, a series of atmospheric rivers caused significant damage and fatalities in California, demonstrating their potential danger.
Climate change is expected to exacerbate the impacts of atmospheric rivers. They are projected to become larger, more frequent, and more likely to occur in series, leading to increased economic damage. This change poses a significant challenge for California, which has experienced prolonged periods of drought over the past few years.
Despite recent rains, portions of California remain “abnormally” dry, and experts warn that the state has not yet escaped the longer-term dry conditions. The period from 2000 to 2021 was the region’s driest in 12 centuries, emphasizing the need for effective water management and climate adaptation strategies.
The current atmospheric rivers offer a mix of relief and risk for California. While they contribute to alleviating drought conditions, their intensity and potential for causing natural disasters highlight the complex challenges posed by climate change and the importance of preparedness and resilience in facing these weather phenomena.