Skiing: Snowpack starts transition to spring conditions

Posted on March 13, 2012 by Bob Berwyn

Breckenridge Ski Patrol holds final avalanche talk of the season (March 15, Tenmile Room at the The Village at Breck) with a focus on spring avalanche risks and wet-snow slab instability

The 'Cirque' between Peak 6 and Peak 5...May 5, 2011. PHOTO BY MATT KRANE.

Public service avalanche presentation from the Breckenridge Ski Patrol.

By Summit Voice

SUMMIT COUNTY — The spring wet-snow avalanche season is starting early this year, thanks to a March warm-up, says Breckenridge ski patroller Matt Krane, warning that the recent spate of warm weather and winds may already be undermining the snowpack with meltwater percolating through the snowpack and lubricating already suspect layers.

A recent wet snow avalanche in Tenmile Canyon is a sure sign that some slopes are already subject to this type of release, and with low temperatures forecast to stay near the freezing mark even at mid-elevations, the problem could get worse before it gets better.

The same aspect one day later, May 6, 2011. Daytime temps in town were in the high 40s-low 50s. PHOTO BY MATT KRANE.

“It’s no secret that this season’s snowpack is ending up a good deal shallower than last winter,” Krane said via email. “According to our weather stats, snowfall-to-date this year is at exactly 70 percent of average as of Saturday. Conversely, as of the same date last season (March 10), we were at 124 percent of average. Things can always change, and they may … this coming weekend, but we are definitely into an early spring-snow transition,” Krane said.

 If you’re heading out into backcountry terrain, terrain which has not seen the “stabilizing* action of constant skier pressure — as in the steep reaches of ski areas — not only do you need to know your terrain, weather, snow metamorphosis and temperature gradients, you also need to be guided by conditions and not the calendar,” he said.

In a shot from a couple of weeks ago, a ski patroller practices "protective skiing" to clear the Whale's Tail/Y-Chute area at Breckenridge. In this caee, 12 inches of new bonded well to the old-snow layer. PHOTO BY MATT KRANE.

“If you’ve been to previous lectures, Avy I or II classes, you’ve heard over and over again that avalanche forecasting is an inexact science. Probably the hardest thing to forecast over a winter of digging pits, control work, graphing metamorphosis and temperature gradient…IS wet-slab avalanche activity,” Krane said.

“Given this year’s shallow snowpack, you have to ask: Will the snowpack go ‘isothermal’ more quickly (that is, each layer achieving the same temperature and beginning the true melt-freeze cycle), or, might wet-slab avalanches be more prevalent with fewer layers to retard percolation to the hard crusts and ice layers?” he added.

More from Krane:
“Springtime in the Rockies is the time for wet-slab instability. Wet-slab avalanches have proven to be the most destructive type time-and-time again. Wanna See? Google “French Avalanche Destroys Lift” and watch last week’s video of an extremely large, slow wet-slab avalanche destroying the base terminal of a quad chair in Savoie, with upwards of fifty people in the air. The entire side of the overhanging mountain was laid bare to rock by this event. The Alps have received well-above normal snowfall midwinter; then the temperatures rose dramatically.”
Krane said backcountry skiers are already posting word of great high-alpine spring skiing shots all over Facebook, but he said you shouldn’t be lulled into a sense of complacency.
“Although the near surface layers appear to be in the midst of a melt-freeze cycle,you might find something quite different in a full-depth snow pit analysis.
“To learn a lot more about the winter-into-spring-into-summer snowpack, don’t miss The Breckenridge Ski Patrol’s final “Avy” talk of the season this Thursday, March 15, at the Ten Mile Room at The Village. There’s nothing like getting up before daybreak for a planned ascent to your chosen route while the sun breaks, and warms up the very snow surface you’re planning to descend. Also, there’s nothing like waking up for another day.”

Photographer's track in Forget-Me-Not after gate checks. Seems like last winter. PHOTO BY MATT KRANE.

Clearing morning inversion last week over the Colorado chair. PHOTO BY MATT KRANE.

Opening Imperial Chair/Bowl for the public last week with several inches new. PHOTO BY MATT KRANE.

The same morning inversion over the upper Arkansas Valley, Mt. Elbert at right, from the top of the Imperial Chair. PHOTO BY MATT KRANE.

A second large-scale avalanche within a three-week span ran on the shoulder of Peak 9 a fw weeks ago after a wind storm. The debris field is about 300 yards long by 150 yards wide. PHOTO BY MATT KRANE.

Breckenridge ski patrol avalanche technician Dave Leffler sampling the first taste of corn snow last week after one inch of new snow had softened into the old snow surface, making for some fine "shaving-cream" in Dwarf 1, the tallest of the dwarves in the Snow White terrain south of the Lake Chutes. PHOTO BY MATT KRANE.

 

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Filed under: avalanches, climate and weather, Colorado, seasons, skiing and riding, Snow and weather, Summit County news, Summit County snow and weather Tagged: | , , ,

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