North Columbia

Mostly a wind slab problem, but as the upper snowpack settles, things might start to change. If you see signs of instability, like whumpfs (rapid settlements), or see small rolls peel off, avoid unsupported (convex) terrain features.

Moderate - Wind effect is extremely variable

Thursday: 5-10 cm new snow is expected. Ridgetop winds southwesterly 50-60 km/h in the morning, becoming 30-40 km/h by the afternoon. Treeline temperatures around -4C. Friday: Light snow in isolated areas, no significant accumulation expected. Winds becoming calm. Treeline temperatures around -7C. Saturday: Dry and sunny. Light northeasterly winds. Treeline temperatures around -13C.

On Tuesday, a skier triggered a small wind slab avalanches at 1900 m. There were a few reports of small natural wind slabs above 2000 m on easterly aspects and explosive controlled avalanches were noted in similar terrain up to size 2.5. On Monday numerous natural slab avalanches were reported up to size 2.5 on a variety of aspects and elevations.

Up to 60 cm of recent storm snow sits on a plethora of old snow surfaces including stiff wind affected snow, faceted (sugary) crystals and surface hoar crystals that formed in locations sheltered from the wind. Snowpack tests indicate easy, sudden shears on this interface, indicating a poor bond with the underlying snow. However, so far, avalanches associated with this layer have been relatively small (size 1 to 2) and mostly limited to windy areas or unsupported features. This may change as the upper snowpack starts to become stiffer and denser - if it does we may start to see wider propagation resulting in the potential for larger avalanches. Telltale signs of this will be whumpfs or remote-triggering of avalanches from flat terrain. Deeper in the snowpack exist two layers that could still be important in isolated areas. The first is a spotty surface hoar layer that sits 40-100 cm down, the second is the mid-November crust now buried 100-200 cm deep.