Confidence
Fair - Due to limited field observations
Weather Forecast
Wednesday: Expect clouds to build through the day with alpine temperatures reaching -5 and winds turning to moderate southwesterlies. Freezing levels could reach 1500m. Isolated flurries are possible, with limited accumulations.Thursday: Cloudy skies with temperatures reaching -2 and freezing levels climbing to 1800m. Expect light westerly winds and a chance of isolated flurries.Friday: Expect continued unsettled skies with more isolated flurries, temperatures around -2 and light westerly winds.
Avalanche Summary
Numerous rider triggered and isolated remote/sympathetic events have been reported in high (2400-2700m) north and northeast facing slopes up to size 2.0, all associated with preserved surface hoar.
Snowpack Summary
Recent convective snowshowers (Thursday to Sunday) have given up to 45cm of new snow at higher elevations. The surface snow has been going moist on all aspects up to 2000m and higher on solar aspects due to strong solar inputs. The new snow interfaces are predominantly crusts (sun, wind, meltfreeze) and the bonds within this storm snow are slowly tightening.50-75cm below the surface you will find a melt-freeze crust from previous sunny weather. At the same interface, spotty surface hoar is still being reported (up to 20mm!) in some high, north facing slopes. Where the surface hoar is present, consistent sudden results have been observed. Isolated sudden results have also been reported on the crust interface (South through East aspects, 2000-2300m), where some facetting has occurred.Cornices are huge and may act as a large trigger on slopes below.
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.