Unusually warm temps are expected this weekend, which will increase the avalanche danger at all elevations. The potential for natural large avalanches running full path will increase with the rising temperatures.
Weather Forecast
Mild temperatures to continue until the weekend, with maximum values expected on Saturday (+8C at valley bottom!). Freezing levels to rise to 1900m on Saturday. No new precipiation is expected. Winds to remain light Southwesterly.
Snowpack Summary
Warmer temperatures at TL and below are promoting settlement in the snowpack. Recent new snow has been redistributed by strong SW winds creating wind slab in open areas at all elevations. This sits over a supportive mid-pack at higher elevations. Extensive scouring and cross loading in the alpine.
Avalanche Summary
Helicopter control work in the Columbia Icefields area today produced numerous large avalanches to size 3 on a variety of aspects in the alpine. Avalanches showed good propagation and released either at the storm snow interface or on basal facets. Many ran full path and smaller slides were able to step down to deeper instabilities.
Confidence
Timing or intensity of solar radiation is uncertain
Problems
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.