Wednesday, November 16, 2005

Seeking to be snow savvy?

Early storms and Avalanche Center offer education

Express Staff Writer

Backcountry skiers spent the weekend poking into the fresh snow that has fallen early this season just as another storm cycle swept into the area.

"Overnight, our northern mountains grabbed an unimpressive-looking storm by the horns and squeezed out (eight) to 12 inches of new snow," reported Chris Lundy, an avalanche forecaster posting an advisory Monday on the Sawtooth National Forest Avalanche Center Web site. "On Titus Ridge, winds blew 10-20 (miles per hour) from the northwest, with gusts into the 30s. The southern mountains received more wind than moisture, with only (two) to (three) inches of new snow and northwest winds averaging around 30 (miles per hour) and gusting to 50 (miles per hour) or more."

The Web site and the advisories offer a glimpse into the winter weather patterns and snowpack conditions. Avalanche Center director Janet Kellam says following the advisories through the winter offers backcountry travelers a primary education into safe backcountry travel.

"We will continue to update this early season information as conditions warrant," Lundy wrote Monday. "Backcountry observations are very limited this time of year, so please drop us a line if you get out into the mountains."

The center has a hotline for recorded advisories (622-8027) and a second telephone line where backcountry travelers can report their observations (622-0099).

Kellam said the biggest concern now is how well newer layers of snow are bonding to older layers.

"A few people are getting out up high and everyone is thinking about winter, so we are offering periodic updates to help you dust off your avalanche antennae and start thinking about the developing snowpack," Kellam wrote in her Nov. 10 backcountry advisory and forecast entry.

Upper elevation temperatures remained very warm Wednesday night and Thursday last week. That history is important information for avalanche experts when they look at rating the avalanche risk later in the winter.

"Baldy at 9,000 feet reported temperatures above 32 degrees since Wednesday morning and rising into the low 40-degree range Thursday. Titus Ridge reported a high of 39 degrees Thursday. Morning temperatures have been cold on the valley floors due to a temperature inversion," Kellam reported. "The (previous) weekend snowstorm ended by Tuesday morning (Nov. 8) leaving an average of two feet or more of consolidated snow above 7,500 feet and a mix of crusts and 'glop' at lower elevations."

The snowpack at upper elevations is still thin but surprisingly dense and supportive. Surface crusts are prevalent on all but due-north and east-facing slopes, and warm temperatures may have developed thin crusts even on cooler aspects, according to the snow condition report last Thursday.

Prior to the past weekend, Kellam posed two questions she hoped to answer over the weekend. Is the new snow bonding well to the icy crusts? Is the new snow top-heavy on lighter, drier snow?

Before the weekend, the snowpack was showing good consolidation, but Kellam urged caution on steep, upper-elevation slopes with pre-existing snow that had fallen before last week.

"These slopes will be primarily the cooler aspects ranging from northwest to north- to east-facing or any steep, shady gullies," she wrote on Thursday. "We received a lot of snow and water weight on top of old crusts and weak, faceted snow and the snowpack is still adjusting to such rapid changes."

The most recent storm that ended Monday morning brought some light snow up high with some high winds impacting conditions on high and mid-range slopes.

"Surface wind slabs may remain sensitive for a couple of days," Kellam said Monday. "We've got what looks like a good base on the ground. It's pretty supportive right now where you've got snow."

Last Wednesday, Kellam reported that at upper elevations, the top eight to 16 inches of snow rests upon a much denser layer of snow. Along Titus Ridge off of Galena Summit, she said she continued to see some easy shears at the interface.

"A new load of snow or windblown snow will stress this weak interface or create new slabs on top of it, and they may be sensitive to the weight of a skier or snowmachiner," she said. "As always, the bonding between any new snow and the existing snow surface is a consideration."

Kellam said the area could be looking at a dry spell in the short term.

"Time will tell what he next storm does," she said.

To get the latest information and study this year's archived advisories to catch up on the dynamic of the snowpack so far this season, check the Avalanche Center Web site:

"Near Galena Summit today, I was able to trigger some pockets of wind slab on the ridge crest that broke out 12 inches deep," Lundy reported Monday. "While this isn't very surprising given the weather conditions, what I found more interesting was the amount of wind loading occurring at mid-slope elevations. I was able to ski cut another pocket of wind slab on a steep rollover several hundred feet below the ridge crest. While many people recognize wind slabs at the top of a slope, slabs also exist mid slope that could easily surprise you and take you for a ride. I wouldn't expect the new wind slabs to remain sensitive for long, but if you head out in the next few days keep your eyes open and avoid wind-loaded areas."

Weather and snow conditions

Advisories are posted by the Sawtooth National Forest Avalanche Center: A recorded advisory is accessible on the center's phone hotline: 622-8027.

For Idaho road reports, go to:

To share backcountry observations, fill out an observer form available on the Avalanche Center's Web site or call 622-0099.

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