Avalanche Forecast
Issued: Mar 8th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs, Persistent Slabs and Wind Slabs.
lbaker,
Avalanche Canada
The snowpack remains weak, requiring users to carefully select conservative terrain for a safe day. Avoid shallow rocky terrain where the snowpack transitions from thick to thin and you are more likely to trigger a large destructive deep persistent slab avalanche.
Summary
Confidence
Moderate
Avalanche Summary
On Tuesday, a natural size 2.5 persistent slab avalanche was observed near Golden on a south aspect at 2600 m. Explosives control triggered a few persistent slabs to size 2 and wind slabs to size 1.
On Monday, several cornice triggered persistent slab avalanches were reported to size 3 throughout the region.
Last Wednesday a fatal avalanche incident involving a group of skiers occurred in the Purcell Mountains west of Invermere BC. The size three avalanche was triggered on a southwest facing slope at 2500 m. The weak layer of facets buried in late November that sits at the bottom of the snowpack was responsible for this avalanche.
Snowpack Summary
Up to 40 cm of storm snow from earlier in the week sits over wind affected surfaces. Wind slabs may be found on all aspects due to variable winds in the past few days. A melt-freeze crust covers the surface of steep solar slopes
Buried surface hoar sits 30-60 cm deep in sheltered terrain features, and a thin sun crust exists at the same depth on steep south-facing terrain. Several other layers from January can also be found in the top 100cm of the snowpack.
The lower snowpack is made up of a widespread layer of large, weak basal facets and depth hoar in some areas. this weakness has been responsible for a number of recent very large, destructive avalanches and will continue to be a concern.
Weather Summary
Wednesday Night
Clear skies. Easterly winds 15-25 km/h. Treeline temperatures, high of -12.
Thursday
Mainly sunny with scattered clouds in the afternoon. Southerly winds 10-20 km/h. Treeline temperatures, high of -10.
Friday
Partly cloudy and isolated flurries, 2-7 cm accumulation. East winds 10-25 km/h. Treeline temperatures, high of -10.
Overnight flurries continue 1-5 cm accumulation. Winds switch to the southwest 25-40 km/h.
Saturday
A mix of sun and cloud with isolated flurries, 2-3 cm accumulation. Southwest winds 10-25 km/h. Treeline temperatures, high of -8.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid areas with a thin or variable snowpack.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Surface hoar distribution is highly variable. Avoid generalizing your observations.
- Remote triggering is a concern, watch out for adjacent and overhead slopes.
Problems
Deep Persistent Slabs
The base of the snowpack remains very weak. Very large human triggered avalanches are possible at treeline and above. Avoid shallow and rocky areas, where the snowpack depth is highly variable. This is a very concerning avalanche problem and should stay in your mind when traveling in the backcountry.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Numerous weak layers from January and February exist at all elevations on a variety of aspects. On shaded slopes, these layers generally present as surface hoar, and on sun-exposed slopes they present as facets and a crust.
Avalanches triggered on these layers can step down to the facets at the bottom of the snowpack resulting in a very large avalanche.
These layers can be remotely triggered. Avoid traveling below steep slopes.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Variable winds have transported storm snow into wind slabs that can be found on all aspects at treeline and above. In areas where slopes are receiving direct solar radiation reactivity of wind slabs could increase rapidly.
Be aware that if triggered wind slab avalanches could step down to deeper layers.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 9th, 2023 4:00PM
