Spring conditions are now with us. Solar warming and cornices should be on the radar for riders. The hazard may go higher than forecast in the afternoon.
Confidence
Fair - Freezing levels are uncertain
Weather Forecast
Sunny with cloudy periods for the next few days. No precipitation in the forecast until Friday. Freezing levels will fluctuate with daytime heating rising as high as 1600 m later in the week. Light southerly winds for most of the week.
Avalanche Summary
Reports are beginning to surface of small, loose wet avalanches in steep south facing terrain. A natural cornice failure was observed at 2300m on a north aspect, but did not trigger an avalanche
Snowpack Summary
Recent storm snow is sitting on a variety of surfaces including a 5 cm thick rain crust that exists up to at 2200m. Recent southwest winds have shifted new accumulations into wind slabs in lee terrain. A facet/crust layer buried in mid-March is down approximately 70-130 cm and is still producing hard but sudden results in snowpack tests. This remains a serious concern in the region due to it's potential to produce very large avalanches. Cornices are also a concern these days. A cornice failure may trigger a large destructive avalanche. Solar aspects are now becoming active with daytime warming.
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.