Observations were limited on Friday and uncertainty exists with forecast freezing levels. Be alert to conditions that change with elevation and make observations continuously as you travel.
Confidence
Fair - Freezing levels are uncertain on Saturday
Weather Forecast
Saturday: Light snowfall becoming moderate overnight / Moderate to strong west winds / Freezing level at 1200mSunday: Light snowfall / Light to moderate northwest winds / Freezing level at 800mMonday: Light snowfall / Light southwest winds / Freezing level at 1100m
Avalanche Summary
An impressive natural cycle of slab activity to size 3.5 took place on Thursday with many features running full path. Loose wet activity to size 2 was also observed in terrain that was more rain-affected.
Snowpack Summary
Strong southwest winds, heavy snowfall, and warm temperatures in recent days have formed deep and cohesive storm slabs at treeline and above. Widespread cornice development has also taken place. At lower elevations heavy rain has continued to penetrate the snowpack. The recent storm snow overlies a weak layer of surface hoar or a sun crust that were buried on March 10th. Some areas had strong winds before the surface hoar was buried, so its distribution may be specific to sheltered and shaded terrain features. Some professionals are still expressing concern for the buried layer of surface hoar from February 12th that is now down more than 1.5m in most places. Although unlikely, the new load of snow and wind may overload this deeply buried weak layer in isolated, unsupported terrain.
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.