Avalanche Forecast
Issued: Mar 9th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs and Persistent 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
Avalanche Summary
On Wednesday, two, size 3 cornice triggered avalanches were observed near Golden. The avalanches happened on northerly aspects and stepped down to the ground. Explosives control triggered a few avalanches on both the deep persistent weak layer to size 2 and on the persistent weak layer to size 3.
On Tuesday, a natural size 2.5 persistent slab avalanche was observed near Golden on a south aspect at 2600 m.
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.
SaturdayLast 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 is settling 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 50-70 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
Thursday Night
Mainly clear, becoming cloudy early morning. Southerly winds 15-30 km/h. Treeline temperature low of -12.
Friday
Mainly cloudy and isolated flurries, 1-2 cm accumulation. Southeast winds 10-25 km/h. Treeline temperature high of -10.
Saturday
Cloudy with sunny periods and isolated flurries, trace accumulation. Southwest winds 10-25 km/h. Treeline temperature high of -8.
Sunday
A mix of sun and cloud. Southwest winds 10-25 km/h. Treeline temperature high of -8. Freezing levels rise to 1200 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid areas with a thin or variable snowpack.
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- 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
Valid until: Mar 10th, 2023 4:00PM
