Forecast weather for Wednesday and Thursday is 'up in the air' for now! Pay close attention to weather conditions and forecasts. With low-density snow available for transport, more wind can change the avalanche danger quickly.
Weather Forecast
A Strong upslope system eases into an Arctic High Pressure.Sunday night: Light snowfall, moderate NE winds.Monday: AM flurries, -24 at Treeline. Moderate Easterly winds slowly easing.Tueday: Clear and cold (-20), Light Easterly winds.Wednesday: Warmer (-15). Increased winds likely, but speed and direction differ greatly between forecasts.
Snowpack Summary
Upto 20cm of new snowfall has been reverse loaded by North-East winds onto South and West facing lees; forming soft, easily triggered Storm Slabs over hard surfaces. Snowfall with light winds on Sunday night will make these hard to spot. Elsewhere, stubborn Wind Slabs are now buried. Down 60 - 100 cm is a thick facet layer, of varying sensitivity.
Avalanche Summary
No observations were attempted in poor visibility on Sunday.On Saturday, debris from several large (Size 2) slab avalanches were observed. These were all in the South-West of the park, which received the highest snowfall totals Thursday night. One Wind Slab on Mt Rowe stepped down to the December 9 Persistent Weak Layer (facets).
Confidence
Timing, track, or intensity of incoming weather system is uncertain on Wednesday
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.