The possibility of very large avalanches failing on the deeply buried crust is keeping the Alpine Danger elevated. I don't think we should trust big alpine slopes yet! Check out the forecast details for more info.
Confidence
Fair - Due to variable snowpack conditions on Friday
Weather Forecast
Overnight and Friday: Light precipitation overnight bringing 3-5 mm that should fall as snow above 800 metres elevation by late morning. Winds light westerly and alpine temperatures about -7.0Saturday:Light precipitation under cloudy skies, with light westerly winds and -10.0 in the alpine.Sunday: A Pacific frontal system is expected to move onto the coast during the day on Sunday. Expect a strong Southwest flow with moderate to heavy precipitation amounts.
Avalanche Summary
Explosive control in the Duffey Lake area resulted in avalanches up to size 2.5 that were 30-40 cms deep.
Snowpack Summary
16 cms in the past 24 hours and 52 cms in the past 48 hours brings recent snow fall amounts up to about 135 cms for the Coquihalla Pass area. Duffy Lake area has seen about 60-80 cm. Weaknesses linger within and under this storm snow. Of particular note is surface hoar buried late last week, which is likely well preserved and weak on sheltered open slopes treeline and below. The mid-pack seems to be well settled and strong, and possibly bridging deeper weaknesses. However, it wasn't too long ago when snowpack tests were producing moderate but sudden collapse results on the early November facet/crust combination near the base of the snowpack. Furthermore, favorable slab structure for step-down fractures can contribute to the persistence of this deep weakness.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.