Kurtis Alexander, THE SAN FRANCISCO CHRONICLE
During the first week of January 1995, a powerful storm lashed Northern California, pushing the Russian River over its banks for seven straight days and damaging more than 4,000 properties, what scientists now say is the costliest atmospheric river the West has seen.
A first-ever economic analysis of atmospheric rivers, released Wednesday as another series of these potent weather systems emerged over the Pacific, finds that such events have caused an average of $1.1 billion of flood damage annually over 40 years. The hardest-hit place, across 11 Western states with losses, was Sonoma County.
The 1995 atmospheric river alone resulted in $3.7 billion of damage, according to the study, from a storm that had mudslides covering roads, winds toppling trees and swollen creeks inundating homes. The event, which made landfall in Southern California and moved north, contributed to the total $5.2 billion of losses that Sonoma County has sustained from atmospheric rivers during the study period — 1978 through 2017.
The authors of the report, with the Scripps Institution of Oceanography at UC San Diego and the U.S. Army Corps of Engineers, warned that atmospheric rivers will intensify as oceans warm with climate change and that the losses will only grow. They called for more study of these systems so they can be better anticipated and their effects blunted.