Intense solar radiation or precipitation in the form of rain will rapidly increase the avalanche hazard at lower elevations.
Weather Forecast
Temperatures will remain mild and skies will be broken on Friday. Winds will be moderate NW easing to light late in the day. Precipitation amounts vary from a trace in Jasper Townsite to a possible 10 cm in the Icefields area.
Snowpack Summary
Snowpack remains thin and facetted at lower elevations, but is supportive above tree line. Last week's storm snow has buried a surface hoar layer (Jan6) down approx 30cm. A variety of wind slabs are building on lee alpine, tree line and on open slopes below tree line from moderate to strong southwesterly winds.
Avalanche Summary
Natural slab activity to size 2.5 was observed at treeline and alpine elevations where the new wind slabs released on the January 6th surface hoar layer. Although they did not travel far, they did step down to the basal facets and November rain crust layers.
Confidence
Forecast snowfall amounts are uncertain on Friday
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.
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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.