Wednesday December 28, 2022
San Francisco Chronicle —
Atmospheric rivers can wreak havoc on the West Coast. These “rivers in the sky” stream enormous amounts of moisture from the tropics to western North America — double the flow of the Amazon River, on average.
This moisture can produce downpours that cause widespread flood damage. From 1978 to 2017, this damage amounted to $1.1 billion per year according to a 2022 study. But atmospheric rivers are also crucial for life in California.
“It’s where we get the water supply,” said Anna Wilson, field research manager for the Center for Western Weather and Water Extremes at UC San Diego’s Scripps Institution of Oceanography.
Atmospheric rivers refill reservoirs and build up snowpack that steadily supplies the state with water. They have also ended about 30% to 40% of California droughts, but tracking these deluges has historically been challenging. Atmospheric river landfall forecasts can be off by hundreds of miles, uncertainty that confounds reservoir operators deciding whether to release water in anticipation of flooding.