Avalanche Forecast
Issued: Feb 22nd, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
Tim Haggarty,
Parks Canada
Continued inputs with small amounts of snow and wind through the weekend. With increasing likelihood of wind slab or cornice failure, cautious terrain selection is warranted in thin snowpack areas.
Summary
Weather Forecast
Strong alpine winds Saturday found morning are forecast to decrease becoming light from the SW by the evening as a low clears the region.
Increasing clouds with light snowfall (4-10 cm)expected Sunday afternoon as a second low approaches from the SW and winds again increase to strong in the alpine.
Snowpack Summary
Continued snow transport and cornice growth with winds affecting treeline ridge crests today. 5-10 cm of new snow now burying sun crusts isolated to steep solar facing terrain. Weak, facetted snow near the base of the snowpack persists in much of the range, producing isolated but large avalanches.
Avalanche Summary
A few windslabs in the alpine up to sz 2 were reported on Friday. On Thursday wind slabs were observed up to size 1.5 today along the Icefields Parkway in loaded pockets in the alpine.
A size 2.5 skier remote was reported Wednesday on the scramblers route of Cascade Mountain on a steep SW slope in the alpine, no involvement.
Confidence
Problems
Wind Slabs
Consistent moderate winds, gusting to extreme from the SW have formed slab in the alpine and wind effect can be expected at treeline. Cornices have grown very large in recent weeks, so watch your exposure to them carefully.
- If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Several large avalanches failing naturally on the basal facet/depth hoar have been observed in the last 14days. These are hard to predict, but are most likely in areas with a thin snowpack (~150cm) where the basal facets and depth hoar are prominent.
- Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.
- Use caution in thin snowpack areas.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 23rd, 2020 4:00PM
