Avalanche Forecast
Issued: Mar 5th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
rgoddard,
Avalanche Canada
Reactive wind slabs can be found on all aspects and all elevations throughout our region.
There were two avalanche incidents on Saturday in the Duffey area. More information can be found in the MIN.
Keep in mind that if triggered, wind slabs may step down to the deep persistent slab problem resulting in large avalanches, especially in shallow snowpack areas in the north and east of the region.
Summary
Confidence
Moderate
Avalanche Summary
On Saturday, two avalanche incidents occurred in the Duffey area, both on south aspects between 1650 and 1770 m elevation. We have received reports of touchy wind slabs, likely related to a period of outflow winds from the northeast causing reverse loading. Wind slabs should be expected on all aspects and at all elevations throughout our region. Wind slabs may be more reactive and persist for longer than what is normal due to them potentially sitting on a crust. Reports of these are posted on the MIN page.
In most areas of our region, more natural wind slab avalanches were reported. They reached up to size 2.5. Their elevation was in the alpine and as far down as below treeline. The aspect that they occurred on ranged around the compass.
The deep persistent slab problem remains in our region, especially in the northwestern zones. When making terrain choices, please keep this issue at the forefront of your thought process.
Snowpack Summary
A variety of winds have begun to redistribute the 30 to 50 cm that fell last week, creating reactive wind slabs on all aspects. New snow and wind slabs sit on a variety of surfaces. In some areas, this new snow has bonded poorly to the stiff wind slabs and near-surface faceting formed by recent wind and cold temperatures.
The mid-snowpack is well consolidated. This is not the case for the lower snowpack. There is a widespread weak layer of large sugary facets at the bottom of the snowpack. Recent avalanche activity on this layer has been confined to northern parts of the region in the Chilcotins.
Snowpack depths around treeline range between 200 and 250 cm.
Weather Summary
Sunday Night
Cloudy with clear periods, trace accumulation, winds east 10 to 15 km/h, treeline temperatures -8 °C.
Monday
A mix of sun and cloud, trace accumulation, winds switching to southeast 10 to 20 km/h, treeline temperatures -10 to -5 °C.
Tuesday
Cloudy with sunny periods, 2 cm accumulation, winds southerly 10 to 20 km/h, treeline temperatures -7 °C.
Wednesday
Mostly cloudy, 2 to 5 cm accumulation, winds southeast 10 to 20 km/h, treeline temperatures -10 to -5 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be especially cautious as you transition into wind affected terrain.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Keep your guard up at lower elevations. Wind slab formation has been extensive.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
Problems
Wind Slabs
A period of northeasterly outflow winds on Saturday created wind slabs on south and west aspects including lower elevations than normal. Prior to this, southwesterly winds created wind slabs on north and east aspects. As a result, wind slabs should be expected on all aspects and all elevations.
Wind slab reactivity may persist for longer than is typical due to the weak surface they are sitting on. In sheltered areas, snow that has not been transported by the wind is also sitting on these surfaces and may not be bonding well.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
A layer of weak facets sits near the base of the snowpack. This layer is most likely to be problematic in steep, unsupported, wind-loaded terrain in the northern part of the region around the Chilcotins, Birkenhead, and Hurley.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 6th, 2023 4:00PM
