Avalanche Advisory for 2014-03-14 07:12:18

Last weekend, Mt Shasta had a just over 1 inch of water fall on its flanks with snow levels fluctuating between 6,500 to 8,000 feet. This brought new snow to the mountain and was immediately followed by two days (Monday/Tuesday) of strong northwest winds and one day (Wednesday) of strong easterly winds. The new snow and wind created good conditions for wind slab avalanche potential on many aspects. On Monday (3-10-14), the MSAC got the report of a skier triggered (ascending) wind slab avalanche in the Anaconda drainage of Mt Shasta, approx. 9,200 feet. The avalanche was approx. 400' wide and ran 250' vertical feet. (HS-ASu-R2-D2-I) 3 people caught, partially buried, no injuries. (See photos below)

Another group of backcounytry skiers report seeing evidence of wind slab avalanches (debris) in the Hidden Valley area later in the week. It is likely that the mountain saw somewhat widespread avalanche activity early in the week during the wind event. Most of the slides were small to medium in size and the debris was subsequently eroded away by the wind after slides occured.

After the wind subsided, it turns out that most of our newer snow simply blew off the mountain. The mountain is currently hosting firm, wind blown conditions with pockets of wild looking wind erosional features. The best skiing has ended up being the old snow that is beginning to turn to "corn snow" in the afternoon hours. This weekend, some southerly slopes could host good spring like skiing. For climbers, conditions are getting good on all routes. However that being said, this is the time of year when the snow is smooth and firm, especially in the AM hours. A slip and fall on smooth, firm and sometimes icy snow can result in a slide for life. Self arrest skills with an ice axe and proper crampon use are essential for a safe climb. Further, a beacon/shovel/probe are absolutely recommended for any climbers attempting Shasta currently. Lastly, while the rockfall danger is low currently, rime ice can plaster exposed rocks on Shasta this time of year. As the days warm, the rime ice will flake off and fall onto climbers below, especially on the Avalanche Gulch route. Ice is like a rock and a HELMET should always be worn.
 

Photos below: Skier triggered wind slab avalanche on Mt Shasta, 3-10-14

Wind erosional feature in the Old Ski Bowl, 3-12-14

Aerial photo of the South side of Mt Shasta, taken by local pilot Troy Bainbridge just a few days ago.

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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.