Strong winds will maintain touchy conditions on Monday. Keep seeking out supported lines in sheltered areas while the storm snow settles and bonds.
Weather Forecast
Sunday night: Scattered flurries bringing a trace to 5 cm of new snow. Moderate to strong southwest winds.Monday: Mainly cloudy with isolated flurries and a trace of new snow, increasing overnight. Strong southwest winds. Freezing level to 1300 metres with alpine high temperatures around -5.Tuesday: Cloudy with scattered flurries bringing around 2 cm of new snow, increasing overnight. Strong to extreme southwest winds. Freezing level rising to 1800 metres after a poor overnight refreeze. Alpine high temperatures around -1.Wednesday: A mix of sun and cloud with continuing scattered flurries bringing a trace to 5 cm of new snow. Moderate westwinds. Freezing level to 1600 metres with alpine high temperatures around -3.
Avalanche Summary
Cornice control on Saturday work gave numerous size 1-2 avalanches on north through southeast ridgelines. above 1900m. The cornice failures produced mostly loose dry avalanches from the slopes below with a few smaller slabs only releasing in the storm snow. On Friday, numerous natural storm slab avalanches were reported from North aspects above 1700 m. Periods of sunshine forecast for Sunday could trigger a round of natural slab avalanches and loose dry/wet avalanches.
Snowpack Summary
Up to 50 cm of recent storm snow will initially have a poor bond to the plethora of old snow surfaces including a melt-freeze crust on sunny aspects and all aspects below 1600 m, surface hoar on north aspects above 1600 m. Wind slabs are building on most aspects due to the changing winds and overhanging cornices exist along ridgelines. Deeper in the snowpack, the mid-December and late-November weak layers are composed of crusts and sugary facets, which are down 150-300 cm. These layers are currently dormant.
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.
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.