The prime concern these days is surface hoar buried beneath a dense slab. Use caution moving into new areas, especially in the alpine.
Confidence
High - Due to the number and quality of field observations
Weather Forecast
The ridge of high pressure that has given us mild upper elevation conditions is forecast to move out of BC by tomorrow morning. Cooler air will move into the region bringing an end to the inversion and lowering temperatures in the alpine back to more normal below freezing values. The BC interior should remain dry until Tuesday next week. For more in-depth weather information, visit: https://avalanche.ca/weather
Avalanche Summary
Reports from yesterday indicate that loose-dry natural avalanches ( up to size 2.5 ) out of steep solar affected slopes remain a prime concern. There has also been reported a large, loose-dry avalanche from a North East facing slope in the alpine. Earlier in the week several large avalanches were triggered in the southern Purcells, west of Kimberly, on buried surface hoar. Something to keep in mind when looking for new terrain.
Snowpack Summary
Conditions are quite variable throughout the region. In the southern Purcells, (west of Kimberley), a prominent layer of large buried surface hoar has shown to be reactive to human triggers. In this part of the region, it's buried down 40 cm with a cohesive slab above it. Further north, this surface hoar layer is 60-120 cm down and has been sporadically reactive to skiers, most recently on North West facing alpine slopes near Golden. At alpine elevations, this interface exists as a surface hoar/facet layer sitting on a crust. The lower snowpack is generally considered to be well settled. Solar aspects may now have sun crust from the recent warm temperatures.New and old wind slabs may be found in the lee of ridges and ribs on a variety of slopes, and surface hoar will be forming in protected cool areas.
Problems
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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.
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.