San Diego researchers say the region could start seeing a more intense cycle of drought and rain as the ocean and atmosphere warm.
Scripps Institution of Oceanography researchers are among a team of scientists that expect atmospheric rivers to have a growing impact on Southern California.
The weather systems bring moisture from the growing subtropics to San Diego while blocking colder storms from the north.
Researchers said the dryer periods will last longer, but when it rains, the downpours will be more intense.
This past winter’s cycle of regular storms showed how things are already shifting.
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“We had a sequence of warm and cold events. Cold storms with snow levels down to 2,500 feet. And a few days later a warm storm and atmospheric river, with snow levels up to 9,000 feet with rain on top of the snow," said Alexander Gershunov, a research meteorologist at the Scripps Institution of Oceanography. "Basically, then you get more water coming down the mountain then what comes out of the sky because it also melts the snow.”
Atmospheric rivers will bring wetter and more intense storms to the region while the overall rainfall averages should stay about where they are.
“And we found that it’s due to atmospheric rivers being bolstered in the warmer climate, while the other storms decline. And basically, atmospheric rivers become bigger contributors to the hydroclimate of this region,” Gershunov said.
The findings are published in the journal Nature Scientific Reports.
