Avalanche Forecast
Issued: Mar 3rd, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet, Wind Slabs and Persistent Slabs.
mark herbison,
A Special Avalanche Warning is in effect.
Increasing temperatures are in the forecast and the effect of this first big warm-up of the season will destabilize the snowpack. This special warning is in effect immediately and will last through the weekend
Summary
Weather Forecast
A ridge of high pressure will bring mainly sunny skies, rising temperatures and 30-60km/hr winds from the South West. The freezing level is expected to rise to ~2100m on Thursday with valley bottom temperatures reaching +10. Some snow expected Friday evening into Saturday.
Snowpack Summary
Strong SW winds have scoured exposed slopes and formed wind slab in alpine lee areas and open tree line slopes. In Kootenay and around Lake Louise we are tracking two persistent layers of facets and sun crust down 30-80 cm that are producing avalanches and sudden test results. These layers are isolated but have been reactive to skiers recently.
Avalanche Summary
Sunny skies and warm temperatures will have an affect on solar aspects, triggering loose wet avalanches. Avoid sun exposed slopes if the solar heating is intense, or the snow is becoming moist and mushy.
Two close calls in the Simpson area of Kootenay Park last weekend. South aspect at treeline and below treeline in the burnt forest is the pattern.
Confidence
Problems
Loose Wet
Clear skies and warm temperatures are forecasted over the next few days. The March sun is strong, and will pack a punch on solar aspects, weakening the upper snowpack. Steep, rocky terrain with thin snowpacks will be the most susceptible.
- Avoid ice climbs that are exposed to steep rocky terrain on solar aspects.
- Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.
Aspects: South, South West, West.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Wind Slabs
Sustained strong winds from the SW have blown the available snow into wind slabs in open areas. These could be quite deep in immediate lee areas. Test sensitivity on small slopes with no consequence and extrapolate to bigger terrain.
- Watch for shooting cracks or stiffer feeling snow. Avoid areas that appear wind loaded.
- Use caution in lee areas. Recent wind loading has created slabs over weaker snow.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Two weak facet interfaces exist in the top meter of the snowpack. On south aspects this problem could be associated with a sun crust. These layers are present in many areas, but we have uncertainty on where they will be reactive.
- Use conservative route selection, choose moderate angled and supported terrain with low consequence.
- Dig down to find and test weak layers before committing to a line.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 4th, 2021 4:00PM
