Avalanche hazard will fall as the temperature cools, however, pay attention to changing conditions between sunny and shaded aspects
Confidence
Moderate - Timing or intensity of solar radiation is uncertain on Thursday
Weather Forecast
THURSDAY: cloudy, light southwest winds freeing level 2200m. FRIDAY: light flurries and showers overnight as freezing levels fall to valley floor before rebounding to 2200m, light southwesterly winds. SATURDAY: flurries/showers taper off in the early morning, partly cloudy skies, moderate westerly winds, freezing level falling to 1800m.
Avalanche Summary
A cycle of loose wet avalanches was reported on Monday and Tuesday.
Snowpack Summary
Moist snow can be found on solar aspects and a thin melt freeze crust may form on the surface overnight. Dry snow can still be found on high elevation north facing slopes. Strong south west winds have resulted in widespread wind effect. Thick, stiff wind slabs can be found on north aspects in the alpine. Cornices have grown significantly. In the front ranges, the wind effect may be more extreme with widespread strastugi being reported in the alpine around Castle Mountain. In some areas you may find a supportive crust down 30cm that extends up to around 1900m. A layer of buried surface hoar can be found between 40 and 60cm down and remains a concern west of the Divide. The snowpack rests on a weak crust/facet layer from early December.
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.