Forecast snow and wind are expected to increase the avalanche danger. Be prepared for winter conditions at higher elevations.
Confidence
Poor - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
The first wave of precipitation and strong southwest winds is expected to end Saturday evening, and there should be a short break before the next wave starts on Sunday. The freezing level should gradually drop on Sunday, with most of the forecast 10-15 mm of precipitation coming as snow above 1000 metres combined with moderate easterly winds. Snow/rain should end late Monday morning or early afternoon, but remain cloudy. Mostly cloudy with a chance of sunny periods on Tuesday as the freezing level rises to about 2200 metres.
Avalanche Summary
No new avalanches reported. On Tuesday, our field team members in the north Elk Valley experienced several whumpfs on south facing treed terrain at 2200 m. They also experienced a whumpf of a hard slab near ridge top at 2450 m and saw a deep slab release on a sunny aspect that probably occurred some time in the last week. Recent loose wet avalanches up to size 1.5 appeared to have been triggered by solar warming. On Sunday, a skier-triggered slab released on a weak layer near the ground in Kananaskis Country. Rain, snow and wind forecast for the weekend are likely to drive natural avalanche activity.
Snowpack Summary
Rain is likely to weaken the snowpack below about 2000 m on Saturday, and may cause a natural cycle of loose wet or wet slab avalanches. At low elevations, thin snowpack areas may simply melt. On the highest peaks, new snow will probably be shifted by strong winds into slabs lee to the SW. Cornices may develop. The most prominent snowpack feature is a thick crust 10-30cm below the surface, extending up to around 2200m elevation. The support of this crust is breaking down in response to warm temperatures. Persistent weak layers below this crust still react in snowpack tests and could wake up with continued warming or loading.
Problems
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.
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.