Experts foresee mixed weather

Snowpack levels alarmingly low in some areas of West

Dave Wilkins
Capital Press

January 04, 2008

The new year has started with Western snowpack levels all over the map - literally.

Jan. 1 snowpack ranged from about 50 percent of average in the Sierra Nevada range in Northern California to 283 percent of average along the north Coast Range in Oregon , according to U.S. Natural Resources Conservation Service SNOWTEL data.

A series of storms is expected to bring more rain and snow to the Northwest until about Jan. 10, followed by a drying trend toward mid-month, according to forecasters.

"What happens after that is anyone's guess," said Jan Curtis, a climatologist with the U.S. Natural Resources Conservation Service's Water and Climate Center in Portland .

While the long-term outlook is a bit murky, Curtis expects a La Nina weather pattern to continue, resulting in near-normal winter precipitation totals for the Northwest.

"I think we'll see precipitation pretty close to normal or slightly above normal," he said.

That would be a great relief to many farmers in the region who've been waiting for an end to the drought. Many reservoirs in Idaho ended the 2007 irrigation season nearly empty, and it will take lots of spring snowmelt to fill them.

"We generally need 80 to 110 percent or better snowpack by April 1 to ensure adequate surface irrigation supplies," said Ron Abramovich, NRCS water supply specialist in Boise .

Snowpack levels were highest in Western Oregon and Washington state. The Lewis and Cowlitz basins in southwestern Washington registered 132 percent of average snowpack, while the Coast Range in Oregon topped all locations at 283 percent of average.

Snow levels were below average across Southern Oregon , Nevada and California . Only three basins in Idaho - the Salmon, Weiser and Clearwater - were above average, and then only barely so.

The situation would be even worse in Idaho if it weren't for some storms during the second half of December, Abramovich said.

On Dec. 17, snow depth was 14 inches at Mores Creek Summit north of Boise , according to NRCS SNOTEL data. Just eight days later, it was 44 inches deep.

The stormy trend is expected to continue in early January.

"We still have several storms coming our way, which will help," Abramovich said last week. "The pattern we're seeing now agrees with the typical La Nina pattern."

Idaho gets most of its winter precipitation before Feb. 1, he said.

"The next 30 days will be critical for us," Abramovich said.

While forecasters expect La Nina to remain in effect in the Northwest this winter, it will be a bit different than past patterns. Expect increased variability, with alternating dry and wet periods throughout February and March, forecasters say.

Blame it on climate change.

"We're seeing more variability now than back in the 1950s and 60s," Abramovich said. "It's tougher now to be a farmer or a manager because you can't count on a continuous series of storms coming in."

Staff writer Dave Wilkins is based in Twin Falls , Idaho . E-mail: dwilkins@capitalpress.com.

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