What happened to the rain? California in a dry rut, snowpack shrinks

Scroll through the gallery above for graphics showing updates on California's water storage. 

California is stuck in a dry spell amid what is historically the wettest time of the year. But while the Sierra snowpack is dwindling and rainfall totals are below normal, weather watchers are not concerned about a drought.

"One dry year doesn’t make a drought," said Chris Orrock, a spokesperson for the California Department of Water Resources. "It takes multiple years of below average precipitation. And the second half of the month could be wet."

Meanwhile, state reservoirs remain full from last year's storm-packed winter.

A weather system known as a high-pressure ridge is currently parked along eastern Pacific Ocean, pushing the storm track into the Pacific Northwest and keeping the Golden State dry.

"If you look at weather stories about Seattle right now, they’re getting hammered with storm after storm," said Jan Null, a consulting meteorologist with Golden Gate Weather Services. "The storms are going up over the top of the ridge into the Northwest, but not dipping down over California."

The next possible chance for rain in Northern California and the Bay Area is Feb. 15. Null said long-range weather models show this system will likely be extremely weak, delivering a mere sprinkling. It's difficult to accurately forecast weather beyond a week or two, so the forecast could change.

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While Southern California is currently dry, it did receive significant storms in December and January, and rainfall totals are around normal. More concerning, the Bay Area hasn't seen a round of multi-day heavy rain since Christmas.

The National Weather Service measures seasonal totals using the "water year," running from October to September, and many locations in the Bay Area are well below average since Oct. 1.

The rain gauge in San Francisco on average measures 14.17 inches between Oct. 1 and Feb. 6, but this year it has received just 8.83 inches, or 62% of normal. The Santa Rosa Airport is at 72% of normal and San Jose 46% of normal. (See chart in the gallery above for more numbers.)

"Until we get some rain, those percentages against normal to date are going to keep falling," said Null.

The dry spell is reflected in the latest map from the U.S. Drought Monitor, which indexes indexes several factors, such as precipitation totals and reservoir and snowpack levels, to determine drought conditions. (See map in the gallery above.)

While there are no signs of drought on the Feb. 4 map, 34% percent of the state is now considered "abnormally dry," compared to only 4% on the Dec. 31 map.

"You need two back-to-back years of low rainfall for drought," Null said. "That's a good rule of thumb."

Null added that the impacts of the dry weather vary depending on who you talk to.

"If you are a grower who is feeding cattle on Mount Diablo, it has been wet enough this season where there have been grasses grown," Null said. "But if you’re a resort owner in the Sierra, Presidents' Weekend is coming up and there’s not going to be any fresh powder. And if you’re a water manager, you're probably looking at the reservoirs and thinking it’s a good thing last year was very wet. It’s so dependent on the individual user."

The snowpack was in good shape after storms slammed the Sierra over Thanksgiving and then again over Christmas, but the systems in the new year have been relatively week and the snow supply is slowly shrinking. As of Feb. 6, the snowpack measured 64% of average.

Orrock is hopeful of more storms this winter and said that even amid this dry period, the highest elevations are receiving some snow.

"There are still some areas in California that are still getting some snow," he said. "As long as we don’t get really high temperatures that snow will stay the same. Our water storage is doing well. As long as we have some snowpack that will help replenish the reservoirs, we're OK."

He added, "California climate is so variable and so extreme now. Our wet years are wetter than they were and our dry years are drier than they were."

Amy Graff is a digital editor with SFGATE. Email her: agraff@sfgate.com.