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Is El Niño the Solution to California's Drought?

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For the past four years, skiers and snowboarders have suffered through one of the worst droughts in the history of California. Last year, the Tahoe snowpack on April 1 was so bad, Governor Jerry Brown ordered the state's first-ever mandatory statewide water restrictions. This fall, however, the snowpack is measuring well above average and more storms are on the horizon. And although the strongest effects of El Niño likely won't be felt until mid-December at the earliest, everyone is wondering: will this year's record-breaking El Niño rescue California from its epic drought?

More on El Niño:
What Do You Need to Know About El Niño? These 10 Things.
Was El Niño the Cause of California's Latest Round of Snow?
There's a 90 Percent Chance We're Getting a Strong El Niño
Watch the Enormous El Niño Growing in the Pacific Right Now

At this point, there's not just the potential for a strong El Niño this winter, it's pretty much a guarantee. The National Oceanic and Atmosphere Association (NOAA) notes that "El Niño-related impacts have been occurring around the globe for months already" and in the United States these impacts will be strongest from December through March. That's not to say we haven't already seen the influence of warmer surface waters in the equatorial Pacific, it's just that the strongest effects are yet to be seen.

Because El Niño tends to create wetter and cooler than average conditions across the southern portions of the United States, and warmer and drier conditions across the northern regions, Californians are bracing for what could be an epic winter of rain. But it's important to note that even a wet winter would be, as NOAA put it, "very unlikely to eradicate 4 years of drought."

Even with November's precipitation, most of California is still in an exceptional drought. The most recent U.S. Drought Monitor map, released November 19, provides a good picture of just how severe the state's drought remains.

So what will it take this winter to put a dent into California's water problem? Lots and lots of rain. For multiple years in a row, the state's rainfall amounts have been between 54-75 percent of normal. As NOAA explains, "every region in California is missing at least a year's worth of precipitation," and the southern coast of California (here's looking at you, Los Angeles) is missing almost two year's worth of rain.

California doesn't just need a little bit of rain to end the drought, it needs a ton of rain or snow. Just check out this map of the percent of normal precipitation needed by the end of September 2016:

To put it in perspective, most of California would need to have one of the wettest years on record to get five-year precipitation deficits out of the bottom 20 percent. To get out of the 50th percentile, every region of California would need record-breaking amounts of rain. That means that Los Angeles would need nearly 53 inches of rain this year, more than 15 inches higher than the current record for the wettest year ever.

What does this all mean? It's unlikely that this year's El Niño, no matter how strong it is, can solve California's drought. Even more important, El Niño has the best chance of helping if precipitation falls across the entire state.

In southern California, where the probability of a wet winter is much higher than the northern half of the state, El Niño could bring more rain. But the backbone of California's water supply, delivery system, and reservoir capacity is in Northern California. If heavy rain falls north of Sacramento, where some of the state's largest reservoirs are located, the El Niño precipitation would be much more beneficial to ending the drought. Colder temperatures at higher elevations would also help replenish the state's snowpack.

Drought-relief isn't going to happen overnight, even with an El Niño this strong. The most likely scenario is that El Niño brings above average rainfall this winter, but that the drought remains intact through spring. The best hope is that this year's El Niño makes the drought less extreme.

· November El Niño update: It's a small world [NOAA]
· How deep of a precipitation hole is California in? [NOAA]
· El Niño could be the most powerful on record, scientists say [LAT]
· U.S. Drought Monitor [Official Site]