New snow, winds and temps are creating ideal conditions for slab development in open terrain. A few cornice collapses were observed throughout the day so be sure to avoid traveling underneath these features.
Confidence
Fair - Intensity of incoming weather is uncertain on Saturday
Weather Forecast
Another 10-15cm of new snow is forecast to fall over the next 24hrs. Temperatures are forecast to be in the -8C to -10C range with a freezing level around 1800m. Winds are expected to increase into the strong range out of the SW so keep and eye on local winds because with all the new snow recently and forecast, stability can deteriorate quickly.
Avalanche Summary
3 separate cornice collapses were observed on Mt Murray within minutes of the winds picking up. Several loose dry avalanches up to size one were observed in the storm snow. Expect the upper snowpack to become increasingly "slabby" overnight due to winds and temps and as a result we will see an increase in natural avalanche activity on N and E aspects on saturday, especially at treeline elevations and above.
Snowpack Summary
15cm HST over the past 24hrs. Warm temps promoting rapid settlement in the upper snowpack and even moist surface snow at lower elevations (below 1800m). New snow is quick to for storm slabs up to 30cm thick in open wind affected terrain. Midpack well settled and the 1106 rain crust is down 60-110cm throughout the forecast area. Moderate to hard sudden collapse sheers are being observed in a facet layer below the 1106 crust.
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.
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.