Avalanche Forecast
Issued: Feb 20th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Cornices and Persistent Slabs.
zryan,
Avalanche Canada
Continually assess the bond between new snow and the old surface. Be extra cautious in wind-loaded terrain.
Do not underestimate the influence of the sun on a cold, clear day. Avalanche danger could increase rapidly on sun-exposed slopes when solar radiation is strong.
Summary
Confidence
Weather Forecast
Bundle up in your warmest gear, arctic air is here!
Sunday Overnight: Cloudy with light flurries, clearing into the morning. Light to moderate northerly winds. Alpine temperatures plummet to around -25 C.
Monday: Cold and clear. Light to moderate northerly winds. Alpine temperatures around -25 C.
Tuesday: Cold and clear. Light to moderate northerly winds. Alpine temperatures around -20 C.
Wednesday: Cloudy with light flurries. Light to moderate northwesterly winds. Alpine temperatures around -16 C.
Avalanche Summary
Observations were limited during the peak of the storm on Saturday, but operators suspect a widespread natural avalanche cycle occurred in the alpine and treeline.
In the neighbouring North Colombias, numerous natural and human-triggered storm slabs were reported on all aspects due to rapid loading. Larger natural and human-triggered wind slab avalanches were reported in wind-loaded terrain in the alpine and treeline. Several natural dry loose avalanches were reported out of steep terrain on all aspects.
Snowpack Summary
This weekend's storm brought 15-60 cm of new snow above 1400 m, with heaviest amounts in the north of the region. At lower elevations, a surface crust can be expected from wet snow/rain throughout the storm. Up to 80 cm now overlies the old, hard surface, which is a result of a period of high pressure in mid-February. The layer is comprised of facetted snow, a melt-freeze crust at lower elevations, a sun-crust on steep solar aspects, and hard wind-affected snow in the alpine and exposed treeline.
The mid-January surface hoar/crust layer is now down 50-150 cm in the snowpack. This layer has not been reactive to skier traffic in the past week and is showing limited reactivity in snowpack tests. Although unlikely, the layer could be triggered from a large load like a cornice fall or a shallower slab avalanche stepping down to this layer.
The facet/crust layer that formed in early December is now buried around 150 to 250 cm. Human triggering of this layer is unlikely, except perhaps on a re-loaded bed surface or in a shallow snowpack area. This layer may become a concern during periods of warming or heavy loading.
Terrain and Travel
- Closely monitor how the new snow is bonding to the old surface.
- Minimize your exposure time below cornices.
- Use small low consequence slopes to test the bond of the new snow.
- Shooting cracks, whumphs and recent avalanches are strong indicators of an unstable snowpack.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Minimize exposure to sun-exposed slopes when the solar radiation is strong.
Problems
Storm Slabs
This weekend's storm brought 15-60 cm of storm snow which overlies the February 15th drought layer.
In areas that received greater snowfall, cold temperatures may decrease the reactivity of the more widespread storm slab problem, but deeper, and stiffer slabs will exist in wind-loaded terrain, which probably remain reactive to human-triggering.
Do not underestimate the influence of solar radiation on these cold days! Reactivity could increase rapidly on sun-exposed slopes when solar radiation is strong.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Cornices may have grown significantly with wind and snowfall over the past 3 days. Be especially mindful of overhead cornice hazard if the sun comes out and the storm snow is experiencing strong solar radiation for the first time.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A weak layer formed in late January may be found 50 to 120 cm deep in the snowpack. This layer consists of faceted snow, a sun crust on steep solar aspect, and most notably large surface hoar crystals in sheltered terrain.
Reactivity has begun to taper, but a significant amount of new load may cause this layer to 'wake up'.
The most reactivity on this layer has been seen between 1600-2200 m in open areas in the trees, in cut blocks, and on steep convexities.Terrain features to be suspect of include the lee side of ridges, openings in trees, cut blocks, and burns, especially on northerly aspects where the layer may not be capped by a firm crust.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 21st, 2022 4:00PM
