Avalanche Forecast

Archived

Apr 14th, 2018–Apr 15th, 2018

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Jasper.

Snow continues overnight and through the day Sunday. Best riding is on sheltered areas at Treeline. Avoid traveling or stopping under large slopes or corniced features as they may be sensitive to triggering.

Weather Forecast

Scattered and localized flurries will continue overnight and through the day Sunday. Accumulations may be as much as 4cm overnight and a further 10cm over the day. At lower elevations (under 2200m) expect wet flurries or rain in the afternoon. Winds are expected to shift to the east, remaining light with moderate gusts at ridge top.

Snowpack Summary

14cm HST overnight, with varied localized amounts as unsettled weather continues. Moderate SW winds have certainly overloaded wind slabs and cornices in open areas in the ALP. Persistent instabilities (down 40 to 100 cm) are already sensitive to large triggers like cornices, especially on N asp slopes at TL and ALP elevations.

Avalanche Summary

Road patrols in Maligne and Icefields regions. Very little natural slab activity seen in both regions. It was noted that cornices look huge. Numerous small loose wet slides observed at low elevations and solar asp, up to 2500m. Great information being shared daily on Avalanche Canada's MIN Reports for the Maligne, Whistler's Creek and Ice regions.

Confidence

Intensity of incoming weather systems is uncertain on Sunday

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.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.