Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.
Regions
Cariboos.
Snow, strong wind and warming are a recipe for elevated danger. Conservative terrain use at all elevations is essential this week. Avoid overhead hazard!
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
We'll see warmer temperatures with strong winds and significant precipitation through the forecast period. TUESDAY: Snow (5-15cm) with STRONG southwest winds. Freezing levels near 1700m. WEDNESDAY: Another 15-25cm of fresh snow throughout the day accompanied by moderate south winds. Freezing levels remain at 1700m. THURSDAY: Flurries with another 5cm accompanied by moderate southwest winds. Freezing levels dropping to 1100m.
Avalanche Summary
A widespread natural avalanche cycle to Size 2.5 was reported below treeline on Monday afternoon as temperatures warmed up. On Friday morning, skiers were able to trigger a Size 1.5 storm slab (with good propagation) in a cross loaded slope near a shallow rocky area. Aspect was north/northeast. See here for their great MIN report.
Snowpack Summary
Warming temperatures on Monday afternoon destabilized the snowpack resulting in a widespread natural avalanche cycle below treeline. Use extra caution for the time being in what is normally a 'safer' elevation band. We've had 5-15cm of fresh snow (with moderate to strong southerly winds) each of the past four days. Touchy storm slabs can be found at all elevations with weaknesses within and under this recent snow. Recent moderate to strong southerly winds have created reactive wind slabs at treeline and above. All this recent snow is bonding slowly to faceted snow, thin sun crust on steep southerly aspects, as well as surface hoar in sheltered areas in some parts of the region.About 80-120 cm below the surface you'll likely find the mid-February persistent weakness, which is composed of a thick rain crust up to about 1700 m, sun crusts on steep solar aspects, and spotty surface hoar on shaded aspects. Professionals in the region have also warned that a 'threshold load' has been reached above this interface, particularly where it presents as a crust.Deep persistent weaknesses (over 1.5 metres down) still have the potential to react to human triggers or smaller slab avalanches.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.