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Avalanche Forecast

Archived

Dec 31st, 2014–Jan 1st, 2015

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Sea To Sky.

This is not your typical South Coast snowpack. Continue to exercise discipline with your terrain choices.

Confidence

Poor - Wind speed and direction is uncertain on Friday

Weather Forecast

Synopsis: Warm air riding up and over the arctic air has created an above freezing layer at upper elevations that should stick around through Thursday evening. Looks like we swing back into the storm track Saturday night with a few successive systems that will likely keep things warm and wet through early next week.Thursday: Freezing Level: Valley Bottom, Above Freezing Layer 1300m to 2800m; Precipitation: Nil; Wind: Treeline: Light, NW | Ridgetop: Light, N/NW.Friday: Freezing Level: 300m; Precipitation: Trace; Wind: Treeline: Moderate, W | Ridgetop: Strong, W.Saturday: Freezing Level: Valley Bottom; Precipitation: Trace; Wind: Treeline: Light, SW | Ridgetop: Moderate, W.

Avalanche Summary

Wind slab avalanches were triggered both naturally and by humans Monday and Tuesday on all aspects between 1600m and 2200m. The majority of the activity was size 1, but there were a few larger exceptions where avalanches likely stepped down to the early December crust. One of those was a size 2.5 human triggered avalanche on a SW facing slope around 1800m in the Brandywine area on Dec. 29. One person out of a group of four was caught and carried. The victim was able to deploy their airbag back which likely helped to keep them on the surface. The sled the victim was riding was reportedly completely buried save one ski tip.On December 24 a rider triggered a large avalanche on a north facing feature at 1900m in the Callaghan. The rider was caught, carried, buried and successfully recovered by companion rescue. The crown was 10 to 100cm deep and is believed to have failed on the early Dec. crust.Their are rumors of other avalanche incidents over the last few days but those details haven't made their way into our office yet. Please send in some info via the Mountain Information Network or email: [email protected]

Snowpack Summary

Strong outflow winds on Dec. 28 left due north slopes mostly wind pressed, some are even scoured down to the mid Dec. crust. Hard wind slabs up to a meter deep can be found on south facing alpine features and some degree of cross loading exists on everything but the most wind sheltered terrain..Three primary layers of concern: Late Dec SH (Surface Hoar): Previously covered by 5 to 15cm and present on all aspects/elevations, distribution post wind event is certainly different, but for the time being I would presume that every slope has it until proven otherwise.Mid-Dec SH: Probably a player in very specific areas, most notably near open water below treeline. BUT, its a player in the South Coast Inland so look for it down 40 to 80 cm.Early Dec Crust: Down 40 to 100cm and reported to be on all aspects/elevations. In some places its just a crust, other spots feature mixed forms, small grained facets and even the above mentioned surface hoar on top of the crust. My gut says that surface avalanches in motion could step down to this crust. The mid pack below this crust contains several old crust layers, but they seem to have gone dormant for the time being.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.