Forecast snow amounts for Sunday are light, and not expected to overload the persistent weakness. Watch for hidden hazards buried under the new fresh snow!
Weather Forecast
Sunday: cool temps with cloud and light flurries and 5cm new snow. Monday: temps will remain constant, around -9. Winds will be light SW with moderate to strong gusts. Up to 25cm has been forecast over the day Monday and into Tuesday!
Snowpack Summary
The persistent slab is made up of 3 weak interfaces, all in the top 30 to 50cm of the snowpack. Depth and distribution of these weak surface hoar/facet layers varies with the terrain, vegetation, and shelter; although it has consistently been found in sheltered features at TL and above. Windslabs continue to developed in open areas at TL.
Avalanche Summary
Avi control on Parkers Ridge Friday produced 2 large avalanches, size 2 and 2.5 on a N aspect running as the the persistent slab. Slope was hit with 17 explosive charges. The 18th shot, a large crown appeared up to 1.5m thick x 150m long x 300m wide and buried under 2m of debris for 150m. Interesting display of sensitivity and spacial distribution.
Confidence
Forecast snowfall amounts are uncertain on Monday
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.