Sierra snowpack levels dire, but don’t panic yet

State surveyors in the Sierra Nevada delivered some disheartening news on Wednesday: The snowpack is far below average for this time of year.
In an anxiously watched rite of winter, state Department of Water Resources surveyor Frank Gehrke weighed a tube of snow at Echo Summit and found it held less than a half inch of water, about 3 percent of the historical average for the site.
To get to the site, he walked a barren landscape, where the average snowpack is typically 11.3 inches.  He found an average of 0.4 inches.
Water officials, however, stressed that while the measurements were far less than last winter, it’s too soon to say the state is back in a drought.
“As we’re only a third of the way through California’s three wettest months, it’s far too early to draw any conclusions about what kind of season we’ll have this year,” Department of Water Resources Director Grant Davis said. “California’s great weather variability means we can go straight from a dry year to a wet year and back again to dry.”
Added Gehrke: “There’s plenty of time left in the traditional wet season to reverse the dry trend we’ve been experiencing.”
More representative than a survey at a single location, however, are the state’s latest electronic readings from 103 sites scattered throughout the Sierra.
They’re also disappointing, however. Those measurements show that the statewide snowpack is 2.6 inches, or 24 percent of the Jan. 3 average. The northern Sierra reading was 21 percent of average. The central and southern Sierra readings are­­ ­­29 percent of average and 20 percent of average, respectively.
The snowpack supplies roughly a third of California’s water needs as it melts in the spring and early summer. The greater the snowpack’s water content, the greater the likelihood that the state’s reservoirs will receive ample runoff from melting snow.
The discouraging news comes as La Niña, a weather phenomenon caused by cooling Pacific Ocean water along the equator, is expected to deliver only weak storms to California in early January.
The winter got off to a good start with several storms in November, but last month brought almost no rain across the state, creating one of the Bay Area’s driest Decembers on record.
California traditionally receives about half of its annual precipitation during December, January and February.
A high-pressure ridge off the California coast has been directing storms north to Canada over the past month. If that ridge were to move or break up, storms could deliver considerable rainfall and snow this winter.
Rain is in the forecast over the next several days, but precipitation totals will be modest. Bay Area cities are expected to get a quarter- to a half-inch of rain between Wednesday and Friday. The coastal cities of Santa Cruz and Half Moon Bay will get slightly more, between a half and one inch, with possible thunderstorms.
On Wednesday, Gilroy was one of the wettest spots in the Bay Area, receiving 0.20 inches of rain over the 24-hour period that ended at 4 p.m. Wednesday, said Rick Canepa, a meteorologist with the National Weather Service in Monterey.
Morgan Hill followed with 0.18 inches, San Jose with 0.17 inches, Fremont with 0.15 inches, Redwood City with 0.14 inches, Hayward and Livermore with 0.10 inches, Oakland with 0.08 inches and San Francisco International Airport with 0.02 inches. There was no measurable rain in downtown San Francisco.
“I would say the storm door is cracked open a little bit,” said Steve Anderson, a meteorologist with the National Weather Service. “It’s not wide open, but we’re finally getting the high pressure out of here so systems can start coming into the West.”
The incoming weather will have only minor impact in the mountains, where three rounds of small storms are headed to the Sierra, according to Bryan Allegretto, a snow forecaster for the Squaw Valley-Alpine Meadows resort.
On Wednesday night, the resorts were expecting light rain showers, with snow levels falling to around 9,000 feet, then tapering off Thursday, according to Allegretto.  From Thursday night through Saturday, a slightly cooler storm moves through, with a coating of a few inches of snow by Saturday above 7,000 feet. There could be a third storm early next week. Then a drier weather pattern returns for the weekend of Jan.13 and 14.
On the other side of the continent, meanwhile, a powerful winter storm is expected to deliver more cold and snow on Thursday. Schools will be closed in New York City, and Boston is braced for another 10 to 14 inches of snow to blanket the city.
Virginia, where up to a foot of snow is predicted in places, has declared a state of emergency. Miami, with lows in the 40s, lost its usual caliente swagger. It’s even near freezing — 35 degrees — in traditionally steamy New Orleans.
One bit of good news in California is that’s the state’s massive reservoirs — the traditional measure of vulnerability during drought — are in good shape because of last year’s near-record precipitation. Groundwater levels last winter also recovered a bit because more water was stored in underground basins than was drained.