Another 10cm of snow yesterday has loaded the Jan 4 weak interface. Make good terrain decisions today, knowing this critical layer is reaching it's load limit.
Weather Forecast
Wednesday brings increasing cloud, scattered flurries, moderate SW winds at ridge-top, and freezing levels near valley bottom. As we head into Wednesday evening and Thursday, a strong system will push in, delivering moderate to heavy snowfall through Thursday afternoon. Expect 25-35cm of snow with strong SW winds and freezing levels near 1700m.
Snowpack Summary
Wind accompanied the 10cm of new snow yesterday, forming soft slabs in alpine and tree-line lee features. Below this new snow there is variable wind-effected snow in the alpine and settled, very soft slab at tree-line and below. Whumphing and cracking on the Jan 4 persistent weak layer, now buried 50-80cm, is still being reported.
Avalanche Summary
Poor visibility during the snowfall yesterday limited most observations. However, Macdonald Gully 3, a steep, planar N-facing alpine start-zone, kicked out a size 2.5 yesterday, covering most of the fan in the valley bottom. Otherwise, loose avalanches to size 1 were observed from steeper, rocky features.
Confidence
Due to the number of field observations
Problems
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.
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.