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Among the 'climate monsters' that afflict California, Megadrought is the most reliable

Paul Duginski, Los Angeles Times on

Published in Weather News

LOS ANGELES -- As is appropriate for the state that is home to Hollywood, the climate monsters that bedevil California have names that sound like they came from B-movies -- the Blob, Godzilla El Nino, Megadrought.

One monster in particular, Drought, has more than overstayed its welcome, according to a new study in the journal Science. So much so, according to the study, that a climate-driven megadrought that is as bad or worse than anything known in prehistory may be developing.

Southern Californians, emerging into the sunshine after an unusually wet stretch of spring, are likely to say, "What drought?"

Rainfall in downtown Los Angeles, for example, was more than twice what is considered normal in November and December. But then Angelenos got "bageled," as climatologist Bill Patzert puts it. January and February, normally the wettest months, formed a dry hole in the middle of the rainy season. When Los Angeles should have been getting 3.12 and 3.80 inches in January and February, it got 0.32 and 0.04 of an inch, respectively.

From October through March, 40 atmospheric rivers made landfall on the West Coast, according to the Center for Western Weather and Water Extremes at the University of California, San Diego's Scripps Institution of Oceanography. Of those, seven were considered strong, and only one of those strong storms made landfall in Northern California -- on Nov. 26. The rest hit Washington and Oregon, and no strong atmospheric rivers affected Central or Southern California.

During the previous year, 41 atmospheric rivers made landfall on the West Coast, but they were more spread out. More, stronger atmospheric rivers making landfall in California resulted in more precipitation in 2018-19.

 

"We are working on how best to count (atmospheric rivers), which is trickier than it might seem," said Marty Ralph of Scripps. The period from October to March was especially low for atmospheric river counts in California and high in the Pacific Northwest, Ralph explained. The previous year was closer to normal overall but a bit above average for California.

Five moderate atmospheric rivers made landfall in California, all in December. Normally, four or five strong ARs can constitute a rain year, Patzert said.

In January and February, as a strong, stable polar vortex developed, high pressure in the eastern Pacific blocked storms aiming at California and sent them to the north, into the Pacific Northwest. The polar jet stream adjusted to the north, and the contiguous United States had its sixth-warmest winter on record.

Meanwhile, talk of "the Blob" returned as global ocean temperatures rose to the warmest on record, continuing a decadelong trend, and die-offs continued in marine ecosystems in the eastern Pacific.

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