Avalanche Forecast
Issued: Jan 6th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Loose Dry and Deep Persistent Slabs.
william lawson,
Parks Canada
Timing of the incoming storm is still uncertain, but be aware that as snow accumulation intensifies the avalanche hazard will quickly increase.
Summary
Weather Forecast
A cold front moving in will bring more precipitation to the region, expect accumulation values between 15-30cm by Wednesday. This new snow will arrive with threshold wind values for snow transport. By the end of the week an arctic air mass will move in bringing cold temps and clear skies.
Snowpack Summary
20-40 cm of storm snow, strong Westerly winds and mild temperatures is promoting storm and wind slab formation. At tree line, new snow sits on pockets of surface hoar in sheltered areas and sun crust on steep solar aspects. Generally, the upper snowpack of denser snow sits over a weaker lower snowpack consisting of facets, depth hoar and crusts.
Avalanche Summary
Explosive control Monday produce numerus results up to size 3. The majority of the avalanche activity released from upper snowpack instabilities. One deep persistent slab was triggered from a slope that had no previous avalanche control on it, resulting in a size 3 with 1.5m crown. Limited natural avalanche activity was observed.
Confidence
Problems
Storm Slabs
An additional 20-30cm of snow Tuesday, Wednesday will add to the previous storm slab problem. At upper elevations this problem could be associated with additional load from moderate to strong winds.
- Use caution in lee areas. Recent wind loading have created storm slabs.
- If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Loose Dry
While winds stay elevated and precipitation continues to come in, loose dry avalanches will be a problem in steep terrain. These small events can be enough to trigger a slab on slopes beneath cliffs or on ledges in gully features.
- Be very cautious with gully features.
- Use caution above ledges and cliffs where small avalanches may have severe consequences.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
We have seen a few examples of these slabs becoming reactive during the storm. These large avalanches reach run out zones. As loading continues over the next few days, avoid exposure to overhead avalanche terrain.
- Avoid shallow snowpack areas where triggering is more likely.
- Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 7th, 2020 4:00PM
