Drought eases in Northern California but still severe down south, says NOAA

It comes as no surprise to anyone living in Southern California that the drought is still going strong in the region, and forecasters with the National Oceanic and Atmospheric Administration said that will likely continue through the spring and summer.

NOAA's annual spring outlook predicts above average precipitation in parts of California, like the Central Valley, but not in the south. Overall, temperatures are expected to be warmer than average as El Niño's effects wane.

Still, the wet winter in parts of the state have helped ease drought conditions to the north and left water resources more "favorable" than they have been since 2011, said Rob Hartman, hydrologist-in-charge of NOAA's California Nevada River Forecast Center.

"The last two weeks have really gone a long ways towards brightening that picture with some significant winter storms that have arrived," he said of recent rains in Northern California.

Large reservoirs like Lakes Shasta and Oroville are currently above their historical average for this time of year. That's in stark contrast to in Southern California where reservoirs are still quite low.

Hartman said drought conditions in the southern region remain "every bit as severe as they have been."

This is almost the opposite of what many forecasters predicted based on rainfall patterns from previous El Niño years. Last fall, it was assumed  Southern California would see the bulk of the rain while things would be drier in the north.

"Every El Niño event is different," said Jon Gottschalck with NOAA’s Climate Prediction Center. He stressed initial predictions were based on probabilities calculated from past El Niño events. He said those types of forecasts always leave room for the chance things could turn out differently.

Gottschalck said that weather patterns in the tropics may have altered the outcome of this particular storm season, sending rain further to the north than in the past. Researchers are currently investigating this and other theories, he said. 

Still, strong precipitation in the north has been a boon for the whole state since water providers in the south rely on the snowpack in the northern and central Sierra Nevada mountains. Typically that snow melts gradually in the spring and summer to fill aquifers and accounts for about a third of the state's annual surface water supply. This year's snowpack is markedly improved from a dismal one last year.

California snow depth on March 16, 2016 (left) and March 16, 2015 (right).

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National Oceanic and Atmospheric Administration

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NOAA forecasters predict that for April through July,  there will be near normal snowmelt runoff from the Sierra starting at Yosemite National Park and northwards. South of that region will see below normal snowmelt. 

As for when the drought might end? After roughly four years of dry weather, Rob Hartman said it will likely take multiple years of wet weather to reverse course.

"We've dug a very deep hole," he said, adding that the state missed one to two years of precipitation during the drought.

The state's Department of Water Resources has decided to allocate only 30 percent of the water requested by cities and farms in response to on-going water shortages.