This is not your typical South Coast snowpack. Potentially touchy recently buried surface hoar means you need 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
No new avalanche activity to report from Tuesday, but on Monday numerous wind slab avalanches ran naturally and were triggered by skiers/vehicles to size 2.5 on SE through SW facing features between 2000 and 2200m.A member of a very experienced ski touring party was caught and carried by an avalanche on an alpine feature near Tenquille lake Monday. Aspect/bed surface unknown at this time.
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: Down 60 to 80 cm, it is becoming harder to trigger, but snowpack tests are still showing that it has potential for wide propagation. It appears to be most reactive in sheltered treeline locations.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.