Avalanche Advisory for 2014-03-08 06:58:49

Overall good snow stability was found yesterday during a tour of Casaval Ridge and Avalanche Gulch. Smooth snow above treeline and good skiing conditions have brought many folks up onto the mountain. A handful of skiers descended from Redbanks yesterday. Snow conditions range from firm, frozen crust, wind packed powder, to smooth and creamy! Lower elevation crusts were sometimes breakable by a skier and sometimes not. Weak layers in the snowpack have varied from location to location. Most common has been failures at or near buried crust layers. However, a pit dug on an east facing aspect of Casaval Ridge yesterday yielded a 2-5 cm weak layer of graupel, about 30 - 40 cm deep. Stability tests showed moderate stability within this weak layer and full slope propagation not likely. (CT11-Q2/ECTN22-Q2)

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Commentary From 3-7-14

Of note since last week, at least two avalanches occured in Avalanche Gulch. Both were assumed to be naturally triggered. The larger slide started near The Heart and ran down below Lake Helen, splitting the morain. (D2/3, R2.5)

Photo courtesy of Chris Carr, Shasta Mountain Guides. This photo shows the toe/debris of the larger slide that occured sometime on March 2nd or 3rd. Green Butte and Sargents Ridgelines are in background.

The second, smaller slide occured off of Casaval Ridge and slid down into climbers gully in Avalanche Gulch. The slides were thought to be wind and storm slab avalanches, although the larger of the slides appeared to look like a wet slide due to it's gouging of the snowpack. However, due to the high elevation of the start zone, a wet slide is doubted and it was likely just heavy debris.

Photo courtesy of Chris Carr, Shasta Mountain Guides. Wind Slab avalanche off of Casaval Ridge expected to have occured March 3 or 4th. Lake Helen is up and to the right, out of the photo.

Overall, a thick (2-3 inch) rain crust dominates our backcountry snowpack. I was able to wiggle up to 8,500 feet yesterday in the Old Ski Bowl before visibility became nil. Of course when I returned to Bunny Flat the clouds lifted. Below the crust, very moist. greasy snow exists. While this could cause concern for wet slides, below freezing temperatures last night and said crust will keep this problem unlikely today. The primary concern will be for pockets of wind slab avalanches that have formed on the upper mountain near ridgetops and bowls. These will be found above the rain/snow line, greater than 9,000 feet.

Stability test at test pit yesterday at 8,100 feet, southeast aspect, 31 degrees resulted in an ECTN-Q3 and CT11-Q3@120cm from ground.

Photo courtesy of Chris Carr, Shasta Mountain Guides. Powder riding in Avalanche Gulch from this past week.

2014-03-06: Test pit profile, 8,100 feet, SE, 31 degrees, ECTN-Q3 and CT11@120cm

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While Northgate, Brewer Ck and Clear Ck trailheads are officially closed, the bathrooms are still open with packout bags inside, and one can still access the Mt Shasta Wilderness. However, your summit pass and wilderness permits must be purchased at McCloud or Mt Shasta Ranger Stations. NO DOGS are allowed in the Mt Shasta Wilderness OR Sierra Club Property. Thanks!

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Terrain:  Remember most of the terrain that we like to play on is greater than 30 degrees.  Avalanches are possible on anything steeper than 30 degrees.  Avoid cornices, rock bands, terrain traps and runout zones of avalanche paths.

Weather:  Most of our areas avalanche danger will occur 24-48 hours after a storm. We still can see persistent weak layers from time to time and we always will be sure to let you know about that!  Heed the basic signs: Wind (significant snow transport and depositions), Temperature (rain/snow/rain/snow, which in turn weakens the snowpack), and Precipitation (Snow or rain add weight and stress to the current snowpack).

Snowpack:  If snow accumulates, give the snowpack a chance to adjust to the new snow load before you play on or near steep slopes (greater than 30 degrees).  Most direct action avalanches occur within 24-48 hours of recent snowfall.  Watch for obvious signs of snowpack instability such as recent natural avalanche activity, collapsing of the snowpack (often associated with a “whumphing” sound), and shooting cracks. If you see these signs of instability, limit your recreation to lower angle slopes.

Human Factor: Don’t forget to carry and know how to use avalanche rescue gear. You should NOT be skiing or climbing potential avalanche slopes without having beacons, shovels, and probes.  Only one person in a group should be exposed to potential avalanche danger at a time.  Remember, climbing, skiing, and riding down the edge of slopes is safer than being in the center.  Just because another person is on a slope doesn’t mean that it is safe.  Be an individual!  Make your own decisions.  Heed the signs of instability: rapid warming, “whumphing” noises, shooting cracks, snowing an inch an hour or more, rain, roller balls, wind loading, recent avalanche activity.