Dry winter ahead?

A light storm rolled into Sonoma County early Friday, but it was not expected to drop much rain, National Weather Service forecasters said.

"We're easing into the new year, with mild winter weather, no high winds, no heavy rains, just a little soaking in, gradually catching up," said Steve Anderson, a meteorologist.

The rain Friday was only expected to drop a quarter of an inch in Santa Rosa and an inch in Sonoma County's wetter areas, such as Cazadero and Rio Nido.

"It's a typical Gulf of Alaska storm," Anderson said.

So far this rain year, which began July 1, rainfall is about half of normal. Santa Rosa had received 6.65 inches of rain as of Jan. 1, compared to a normal 11.45 inches.

Tim Anderson, a Sonoma County Water Agency spokesman, said it's too early to make any judgments about rationing or drought. Spring, the wettest part of the year, is still ahead.

Last year, the Water Agency for the second year imposed a 15 percent water conservation mandate to save water in Lake Mendocino to be released for the fall salmon run.

The reservoirs serving Mendocino, Sonoma and part of Marin counties are low. Lake Sonoma's water pool is at 76 percent of capacity, Lake Mendocino at 40 percent and Lake Pillsbury at 20 percent. That's down a bit from past years, but water officials said any water that falls now still would be released from reservoirs to make room for flood storage.

"After March 1, that is when we can store the rainfall, that is what we are concerned about," Anderson said. "It's low and it's interesting, but it's not critically important right now."

However, Sonoma County has had a series of dry springs: 2002, 2004, 2007 and 2008.

"The trend is not favorable," Anderson said. "But you know how the weather is; it can change tomorrow."

The weather service announced this week that a La Niña pattern has taken hold across the Pacific. Marked by a cooling trend in the waters of the equatorial ocean, La Niña usually diverts the jet stream north into Canada, bringing dry conditions to California.

La Niña was also present last winter. Rain and snowfall virtually disappeared in Northern California after last January.

This year's La Niña looks stronger and longer-lasting, said Bill Patzert, a climatologist at NASA's Jet Propulsion Laboratory in Pasadena.

"The dice are pretty loaded here against a big snowpack and a heavy rainfall," Patzert said. "But you know, this is one of those things where I really love to be wrong."

December brought a week of welcome snowstorms to the Sierra Nevada, California's water bank. Snow totals for the winter so far exceed last year at this time but are still below normal.

Though it did rain and snow over Christmas, Dave Reynolds, meteorologist in charge of the weather service's Bay Area bureau, said currents associated with La Niña pushed the heavy precipitation north of California. More of the same could be ahead.

"Needless to say, this pattern is not good for the water supply," Reynolds said via e-mail.

El Niño is the more familiar pattern. Named after the Spanish term for "Christ child," because it usually emerges in the Pacific around Christmas, El Niño warms the equatorial Pacific and typically brings wet weather to California.

La Nina, or "girl child," is harder to predict. It has brought both terrible droughts and terrible flooding to California.

Today and Sunday are expected to be sunny and clear before a weak system brings in a chance of showers Monday and Tuesday, Anderson said.

There were few reports of problems associated with the rain or wet roads, in part because many may have taken Friday off after the New Year's holiday.

"When I came in, I don't think there were even six cars on the road," CHP Officer Barbara Upham said Friday morning. "I think a lot of people have the day off."

The benign beginning belies the extremes that put 2008 into the weather record book: May 15 was 100 degrees, the hottest May 15 for Santa Rosa on record, and Nov. 14 was 88, a record for that fall day.

Spring 2008 was also record-breaking. From March through June, Santa Rosa received 0.65 of an inch of rain, the driest spring ever for a period for which the average is 7.4 inches.

Although not record-setting, there was a heat spell from May 13 to 17 in which high temperatures were above 86 each day, and the cold spell of Dec. 14 to 20, when five of seven nights were freezing or below.

The wettest period last year was Jan. 3 to 8, when 5.36 inches of rain fell which, although damp, was also not a record.

This article includes information from Staff Writer Bob Norberg and the Sacramento Bee.