got 134% of its average rainfall San Jose suffered surprise flooding that inundated hundreds of homes and a retaining wall threatened to collapse at California’s second-largest reservoir, triggering an order to evacuate more than 100,000 people downstream of filled-to-the-brim Lake Oroville. By the end of the 2016–17 water year, downtown L.A. Storms were so intense across California that they ended a punishing drought that ran from 2012 to 2017. In fact, La Niña was present during a spectacularly wet season: the winter of 2016–17. has received more than 11 inches of rain - more than double the average 4.91 inches for that time, and also above the entire December-January-February average of 9.41 inches. Since the start of December, downtown L.A. And that pattern fit the previous two years.īut this winter, it changed. Typically, La Niña produces dry winters in Southern California. Easier to understand was the bottom line, as a center’s statement noted: “The greatest chances for drier-than-average conditions are forecast in portions of California,” as well as other southern parts of the nation. Those subtleties, however, tend to get less attention. because that is the state of the science,” DeWitt said. “These probabilities are going to be relatively modest. Taking the midpoint of that forecast - say, 40% - that meant there was a 35% probability of near-normal precipitation and a 25% chance of above-normal precipitation, said David DeWitt, director of the Climate Prediction Center. Though winter isn’t over, and a renewed dry spell can’t be ruled out, the significant storms have defied expectations of a dry winter. Downtown Los Angeles has logged more than 13 inches of rain since October - more than 90% of its annual average of 14.25 inches. San Francisco was drenched with more than 18 inches of rain since Christmas, posting its wettest 22-day period since 1862. The Sierra Nevada has a snowpack of 240% of average for the date, and 126% of where it should be by the start of April. Despite La Niña’s presence, a robust series of 10 storms brought impressive precipitation across California, spurring floods and landslides, increasing reservoir levels and dumping eye-popping snowfall in the mountains. El Niño - a warming of sea-surface temperatures in the tropical Pacific - seemed synonymous with wet winters for Southern California, while La Niña was a heralder of drought.īut the would-be model didn’t hold up this winter. For decades, two climate patterns in the Pacific Ocean have loomed large in predicting weather in California and other parts of the globe.
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