Friday, February 2, 2007

January precip among record lows

Change expected in February

Express Staff Writer

Joan Scheingraber walks her dog in Quigley Canyon Wednesday amid abundant sagebrush and marginal snow cover. This January has been one of the driest on record in Central Idaho. Photo by David N. Seelig

January 2007 will go down in history as the eighth driest January in Ketchum since 1909.

A total of just .38 inches of precipitation, or 7.5 inches of snow, was recorded at the Ketchum Ranger District last month. A trace of snow fell Tuesday, Jan. 30, with no recorded precipitation.

The last measurable precipitation fell Jan. 7 with 2 inches of snow, or .12 inches of water.

The dry weather took its toll on the Big Wood Basin's snowpack, which had fallen to just 71 percent of average by Jan. 31 after a promising start in November and December.

The National Resource Conservation District manages 83 snotel—short for snow telemetry—sites throughout Idaho, including nine in the Big Wood Basin. The sites are basically remote weather stations that provide automated data on precipitation, snow depth and temperature.

The snow-water equivalent, which measures the amount of water in the snowpack, was just 60 percent of average at the Lost-Wood Divide snotel site—the lowest in the Big Wood Basin—on Jan. 31. The snotel at the Soldier Ranger Station north of Fairfield was the highest in the basin at 80 percent of average on Jan. 31. Other snotel sites in the basin include Chocolate Gulch, Galena Summit, Galena Lodge, Dollarhide Summit, Camas Creek Divide, Vienna Mine, and Hyndman.

Only the Panhandle Region in northern Idaho was close to normal at 91 percent of average.

Countering the dry weather is the cold, which has preserved the snow on Bald Mountain. Temperatures didn't climb above freezing for 10 consecutive days between Jan. 12 and Jan. 21, with the lowest temperature recorded at minus 16 on Jan. 14.

The cold has allowed snow guns to pump out man-made snow almost nonstop on Baldy, which has kept groomed runs soft. But even off-piste conditions are holding up, especially on north- and east-facing aspects, where bumps are chalky and grippy.

The culprit of the unusually dry weather is a massive high pressure system that has been parked off the Pacific Coast for four weeks.

Jack Messick, a meteorologist for the National Weather Service in Pocatello, said the high has been intensified by an area of low pressure over Canada's Hudson Bay.

Messick said the combination of the high pressure in the West and the low in the East has caused winds to draw extremely cold and dry weather south into the United States out of northern Canada.

"When air is coming out of Polar regions like the upper North American land mass, there is no opportunity for that air to collect moisture," Messick said. "The air doesn't track over the ocean, so it stays really dry."

Messick said the phenomenon is typical during El Niño events, and one is occurring this year. El Niño refers to a warming of the equatorial Pacific, which can cause a change in global weather patterns. Typically, El Niño events keep the Pacific Northwest and northern Rockies dry and hammer Southern California with rain and the Sierra Nevada and southern Rockies with heavy, deep snow.

But that's not the way things have panned out this winter—so far.

Washington and the Front Range of Colorado have been the big winners through the end of January. Snowpacks in both areas were between 110 and 150 percent of normal.

The Sierra Nevada and Southwest—New Mexico excepted—is bone dry, with snowpacks hovering around 50 percent of average in the region. A year after record snowfalls buried Mammoth Mountain under more than 52 feet of snow, the Eastern Sierra resort had only received a little over 6 feet of natural snow by the end of January.

But things could change soon.

The Climate Prediction Center, which specializes in long-range forecasts, is calling for above-average precipitation along the entire West Coast and portions of the northern Rockies by the second week in February.

"Patterns change very slowly during El Niño episodes, anywhere from 30 to 45 days," Messick said. "It's been about 30 days. We may be heading into a change here for February."

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