Heavy rains predicted for winter

Northern California is staring at a relatively calm start to winter, but could see the kind of storms that last year blanketed the Sierra Nevada in snow and dumped more than 10 inches of rain on the southern part of the state in mid-December, according to AccuWeather.com.

Tom Kines, a meteorologist with the AccuWeather.com Long-Range Forecasting Team, said it is likely Northern California will see a five- to seven-day period of heavy rains this winter — the kind of storm that could bring widespread flooding.

"That would be a big concern, yes," said Kines.

But when that storm will hit is unknown. It could be in December, but more likely in January or possibly February.

"What were are banking on right now, at least for the first part of the winter through mid-December, is that most of the storms are aiming at Oregon and Washington, which leaves us in a dry weather pattern and probably a warmer weather pattern," Kines said.

But if those storms push south, Northern California could experience a lot of what Southern California got in 2010.

"Last year, California was hit hard when the "Pineapple Express" set up from Dec. 17 to 22, producing massive flooding and 13 feet of snow in the Sierra," said Paul Pastelok, a long-range meteorologist and leader of the AccuWeather.com Long-Range Forecasting Team.

"The Pineapple Express could develop for a period this winter and take aim at Northern and Central California. That could lead to monster snowfall and heavy valley rain with the risk of flooding and mudslides," said Pastelok.

The so-called "Pineapple Express" is a weather pattern defined by strong, persistent flows of tropical moisture that originate around the Hawaiian Islands and bring the rain to the West Coast, according to AccuWeather.com.

In general, AccuWeather.com expects December to be fairly typical for Northern California with near-normal precipitation and near- to slightly above-normal temperatures.

January is forecast to turn out dryer than usual, with normal temperatures as well.

From late January into February, however, a transition to chillier weather is predicted to take place, as the overall jet stream pattern over the West Coast undergoes some major changes.

That opens the doors for wet weather.

Big, cold storms are expected to hit the northern Rockies and surrounding states, and could push far enough south to impact the North State, Kines said.

Temperatures will drop in February, as another weather phenomenon, best known as La Nina, takes hold off the coast in the Pacific.

"Right now we are banking on January being close to normal temperatures and in February, slightly below normal temperatures," Kines said.

"While a La Nina like the one we are expecting this winter typically brings lower-than-normal precipitation to Southern California and the Southwest, the concern this year is that something similar to what happened last year could happen again," AccuWeather.com Senior Meteorologist and Western expert Ken Clark said in a statement.

"Storms may be far enough south or wet enough that rainfall could be higher than what is typically expected during a La Nina."

And that, Kines said, is particularly true for Northern California.

Still, the forecast is that precipitation in February is likely to be near or slightly below normal, especially in the northern part of the state.

And while colder, the spring should be dryer than 2011, and that should help North State farmers get their crops in the ground.