As California drought retreats, threat of spring flooding rises
Published in Weather News
LOS ANGELES — Though California may be ending its winter with quenched reservoirs and near record snowpack, meteorologists are warning that the state will face increased flooding risk in the coming months as Sierra Nevada snowmelt fills rivers and streams.
On Thursday, the National Oceanic and Atmospheric Administration’s spring flood outlook reported that drought conditions will continue to improve in much of the state, but the potential for flooding will worsen in the face of heavy snowpack and elevated soil moisture.
“Approximately 44% of the U.S. is at risk for flooding this spring,” said Ed Clark, director of NOAA’s National Water Center. “California’s historic snowpack, coupled with spring rain, is heightening the potential for spring floods.”
The severity of that flooding remains to be seen, however, and depends on a variety of weather factors, experts say.
“It’s going to happen, and the question is whether it happens quickly versus slowly,” UCLA climate scientist Daniel Swain said. “Is it gradual snowmelt — in which case the flood concerns would be mostly minor — or is it more rapid … in which case we could be talking about something in the major flood territory.”
Potential triggers for rapid snowmelt could be an early season heat wave or another series of warm storms, Swain said, both of which could lead to “significant snowmelt flooding, particularly in the San Joaquin Valley and on some of the Sierra east-slope watersheds that drain in the Great Basin and into Nevada.”
The NOAA report forecast moderate flooding in the Central Valley and Sierra, and minor flooding in nearly all of Northern California and along the coast.
For a state that has endued three years of drought, only to be hammered by 11 atmospheric rivers since the start of the year, the prospect of clear sky flooding comes as a mixed blessing as some of that water is bound to soak into badly depleted aquifers.
But for communities that have suffered deaths and displacement as a result of being inundated, the forecast is alarming. Such communities include Pajaro, in Monterey County, which was flooded after a levee breached late Friday night.
The flooding displaced hundreds of people in the primarily migrant town, with no clear timeline for returning. It also raised significant concerns about crop yields in the heavily agricultural region this year.
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