Expect to see sunny breaks over the next couple days. Brief periods of solar radiation could be enough to trigger stubborn persistent slabs or cause cornice failures. Conservative route selection remains crucial at this time.
Summary
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain on Wednesday
Weather Forecast
A weak ridge of high pressure will be the main feature for Monday. Unsettled conditions are expected for Monday night and Tuesday before the next frontal system arrives in the interior on Tuesday afternoon or evening. It is possible that this system will only affect the south of the region. There is currently some weather model uncertainty regarding the freezing levels for the region.Monday: A mix of sun and cloud, freezing level am: surface pm: 700-1200m, ridgetop wind: light variableMonday Night: Scattered flurries 1-2cmTuesday: Mostly cloudy, freezing level am: surface pm: 800-1500m, ridgetop wind: light S-SWTues. Night/Wednesday: Snowfall 10-20cm, freezing level am: surface pm: 500-1000m, ridgetop wind: light variable
Avalanche Summary
We are still seeing relatively small inputs, like periods of strong winds or brief sunny breaks, trigger persistent slab avalanches. Many of these events have occurred on southerly aspects from slopes in the alpine or at treeline. Extra caution is advised when the sun is out.On Saturday, we received reports of isolated natural wind slab avalanches to size 1.5 and natural size 1 cornice releases. The North Columbia region saw natural and human-triggered activity up to size 2 and explosive activity to size 3.
Snowpack Summary
The upper snowpack may have various non-persistent weak layers within the recent storm snow. This includes small surface hoar in sheltered areas, thin sun crusts on solar aspects, rain crusts at lower elevations, and/or small facets. These layers are not widespread and are not expected to persist very long but they continue to produce small slab avalanches. Weak cornices and stubborn wind slabs may also be a concern in some areas.There are three persistent weak layers that remain a concern. The mid-March sun crust/surface hoar layer is down 40-70cm. Recent snowpack tests suggest that the reactivity of this layer is becoming more isolated but many areas still have the potential for human-triggering. The early-March crust/facet/surface hoar layer is down around 80-120cm. Human-triggering has become less likely but the layer still has the potential to produce large avalanches and we continue to see activity stepping down to this layer. The mid-February crust/facet/surface hoar layer is typically down at least 1.5m and direct triggering has become unlikely. However, large triggers like cornices or smaller avalanches can still trigger this layer and produce very large avalanches.
rbuhler,
Avalanche Canada
