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 encroaching Tuesday will bring more precipitation to the forecast region, expected accumulation values range from 20-40cm around Little Yoho. The peak intensity of the front is expected to arrive Tuesday night. As the system passes through an arctic air mass will begging to dominate the region bringing clear skies and cold temps.
Snowpack Summary
20-40 cm of storm snow, strong Westerly winds and mild temperatures are promoting slab formation. Most areas have generally supportive midpack over facets and depth hoar at the base. In deeper areas the snowpack is well settled with limited facets and weak layers. Digging down to see what is in the snowpack in your area is important.
Avalanche Summary
Explosive control in Yoho produced numerus avalanches to size 2.5 releasing from upper snowpack instabilities. Natural avalanche activity has tappers momentarily but expect this to increase once again as more snow and winds are forecasted from Tuesday, Wednesday.
Confidence
Problems
Storm Slabs
An additional 20-40cm 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
