The weather forecast says that you better put your sun screen on for Saturday! The snow pack doesn’t have sun screen, so it might start peeling off if the sun gets too hot or alpine temperatures get too warm.
Confidence
Fair - Timing or intensity of solar radiation is uncertain on Saturday
Weather Forecast
Overnight and Saturday: Light Northwest winds and thin high cloud overnight with freezing down to the valleys. Light West winds with mostly clear skies with a chance of valley cloud and the freezing level rising up to about 1900 metres. A chance of an above freezing layer in the alpine during the afternoon; chance increases as you move to the South.Sunday: Freezing levels dropping to about 1400 metres and alpine temperatures moving down to about -3.0 as the cloud cover thickens in advance of the next pulse of moisture coming from the coast.Monday: West winds building during the day with light flurries becoming moderate snow by evening.
Avalanche Summary
Natural avalanches size 1.0 have been reported from steep un-supported terrain features.
Snowpack Summary
Westerly winds and warm temperatures overnight have continued to develop wind slabs in the alpine and at treeline. Wind slab was reported to be stiffening from fist to four finger hardness. The recent storm slab has been settling and becoming more cohesive. Pockets of slab that were mostly between 30-50 cms deep above the January 23rd weak layer have started to release naturally or when light additional loads have been added (like ski-cutting). As we head into a warming period expect the recent storm slab to become more reactive. The forecast warm temperatures at higher elevations on Saturday may help initiate releases on the January 23rd layer. The deeper weak layer from January 4th is reported to be gaining strength, and I don't expect that we will see releases on this layer from one day of solar radiation and warm temperatures. That being said, if cornices start to fall off from the heating on Saturday, that might be enough of a load to trigger the deeper January 4th layer.
Problems
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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.