Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Regions
Purcells.
Wind slabs, cornice fall, or a person could trigger a deeply buried weak layer, creating a surprisingly large avalanche.
Confidence
Moderate - Timing or intensity of solar radiation is uncertain
Weather Forecast
A building ridge is expected to bring mainly sunny skies with no precipitation for the next three days. A warm southerly flow causes the freezing level to rise as high as 3000 m.For more details check out https://avalanche.ca/weather.
Avalanche Summary
We continue to receive reports of natural and skier triggered size 1-2 wind slabs from across the region. The January surface hoar layer remains a major concern, especially in the north Purcells where it has been responsible for several recent large avalanches. On Friday, a snow cat triggered a size 2 persistent slab on a SE aspect near 2300 m. Last Saturday, a size 3 sledder-triggered avalanche occurred in the Gorman Creek riding area near Golden. Around the same time, a size 3.5 skier-triggered persistent slab avalanche occurred a few drainages to the south of Gorman Creek on a north-facing alpine slope. Forecast warming may increase the reactivity of the persistent slab.
Snowpack Summary
Reactive wind slabs exist in the lee of ridges and terrain breaks at alpine and treeline elevations. These may be found lower in the start zones than normal due to the high wind speed. A persistent weak layer of surface hoar and facets buried in early January is now typically down 40-90 cm. The layer is slowly getting harder to trigger in many areas. However, reports of whumpfing and some recent large to very large avalanches around Golden indicate this layer is still very much a concern, especially in the north of the region. In general, the lower snowpack below this layer is well settled and strong.
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.
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.