yosemite

This image made from a webcam video provided by the Yosemite Conservancy shows Sentinel Dome during a snowstorm in Yosemite National Park on Monday, Nov. 28, 2016. California has vital snow in the Sierra Nevada and positive rainfall totals in many areas after a stormy autumn weekend up and down the state, which is hoping to avoid a sixth consecutive year of drought conditions. The Sierra Nevada functions as reservoir for much of the state’s water supply. (Yosemite Conservancy via AP)

By Dale Kasler and Ryan Sabalow
dkasler@sacbee.com
November 28, 2016 – 2:36 PM

It’s only a beginning. But it’s a strong beginning, and it offers at least a rain gauge’s worth of hope to a state enduring its fifth year of drought.

The National Weather Service said Monday that the rainy season in the northern Sierra Nevada is off to its wettest start in 30 years. Mountain conditions are critically important to monitoring the drought because a major share of the state’s water supply is stored for months as snow.

Citing state data from a string of eight gauges scattered around the northern Sierra, the service said precipitation has come in at about twice the average for this time of year, making for the wettest kickoff to the water year in 30 years. The water year, as defined by climatologists and others, begins Oct. 1.

However, the strong start doesn’t guarantee an end to the drought, or even meaningful relief.

As it is, the rainy beginning is largely the result of one of the wettest Octobers ever, which dumped four times as much rain on the Sacramento region as normal, said weather service forecaster Travis Wilson. Already, there are signs of a slowdown: Despite the wet Thanksgiving weekend, November has been relatively dry, with the Sacramento area getting only about half the normal rainfall.

The two-month wet spell “doesn’t guarantee you anything,” Wilson said.

As if to underscore the forecasters’ caution, the state Department of Water Resources, in the season’s first outlook on water supplies, announced Monday that State Water Project customers can expect to receive 20 percent of their requested deliveries in 2017. The SWP serves some of the biggest water agencies in the state, including the Metropolitan Water District of Southern California.

While 20 percent is twice as generous as a year ago, when the state told SWP customers to expect a 10 percent allocation, it shows that reservoir managers are still conservative. “We could still end up in a sixth year of drought,” said department director Mark Cowin in a prepared statement.

Initial allocations almost always change. The 10 percent allocation ultimately gave way to a 60 percent allocation for 2016.

Forecasters weren’t expecting a wet year at all when the season began. A few weeks in, the National Weather Service declared that the United States would experience a La Niña winter this year. For California, that raised the prospect of an average or even somewhat dry year. The last La Niña, in 2011-12, left California with a dry winter.

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