A small amount of fresh snow and warming temperatures will increase avalanche danger on Saturday.
Confidence
Moderate - Freezing levels are uncertain
Weather Forecast
FRIDAY NIGHT: Light snow possible, 5-10 cm. Expected to stay cool overnight.SATURDAY: Dry. Temperatures warming gradually with a weak above-freezing level layer developing from approximately 1900-2200 m. Winds light northwesterly.SUNDAY: Light snow or rain (6-8 cm at higher elevations). Cooling rapidly through the day. Strong westerly winds.MONDAY: Dry. Freezing level at valley bottom. Light westerly winds.
Avalanche Summary
A few natural wind slabs, storm slabs and dry loose avalanches up to size 2.5 were reported on Wednesday and Thursday on steep slopes on a variety of aspects at treeline and alpine elevations.
Snowpack Summary
15-30 cm of snow sits above a layer of large surface hoar crystals and sun crust. In areas that have had wind effect the recent snow has been settling into a thin but reactive slab above this weak layer, with enhanced reactivity noted at elevations between 1500-1800 metres. In sheltered areas the snow is faceting and lacks cohesion above this layer which is only reactive as dry loose sluffing. Warmer temperatures are starting to consolidate the upper snowpack are will likely make slab avalanches more triggerable.Moderate to strong winds associated with the new snow formed reactive wind slabs on leeward slopes at upper elevations. The middle and lower portions of the snowpack are generally well-settled and strong.
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.