Confidence
Fair - Due to limited field observations
Weather Forecast
An upper trough will move through the Interior tomorrow. The NW flow will bring cooler, dryer air to the region with some pulses of precipitation. Saturday: Overcast with some clearing in the Cariboo's later in the day. Light-moderate precipitation amounts. Ridgetop winds blowing moderate from the NW. Freezing levels near 1000 m.Sunday/Monday: A ridge of high pressure will bring a mainly sunny skies, with cooling and dryer conditions. Freezing levels will be near 1200 m during the afternoon and falling to valley bottom overnight
Avalanche Summary
On Friday a skier triggered size 1.5 slab avalanche was reported. This occurred on an East aspect at 2250 m. Loose wet natural avalanche activity also occurred on a variety of aspects and elevations during daytime warming.
Snowpack Summary
Up to 15 cm of new snow sits on a variety of old surfaces. These include melt-freeze crusts on solar aspects and dry snow with some surface facts and surface hoar on Northerly aspects. Wind slabs have built on lee slopes and behind terrain features. Cornices are huge and remain a concern, threatening slopes below.Buried 60-100 cm down, exists an interface of crusts and buried surface hoar. This is mainly found at upper elevations on all aspects. It seems to be slowly gaining strength, yet this interface has recently become reactive in regions further south. I would remain suspicious, especially of large, steep high-alpine slopes. Dig down, and test layer of concern.
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.