A big change in the weather is in store beginning Thursday. Check out the vlog our field team put together a few days back: http://www.avalanche.ca/blogs
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
The weather pattern is currently super dynamic and tough to pin down with exact metrics, especially on Friday. No precipitation is expected on Wednesday, but winds should begin to ramp up to moderate SW at treeline, Strong W in the alpine. Thursday looks very similar with the potential for a trace amount of snow. Friday should bring 2-15mm of precipitation which will likely start as snow, switching to rain as the freezing level begins to climb towards 2500m. Check back for more updates tomorrow.
Avalanche Summary
No new avalanches have been reported.
Snowpack Summary
Recent sunny weather and high freezing levels have decimated the lower elevation snowpack. As a result the threshold for avalanches in most of the region has risen to approximately 1600m, potentially higher on solar aspects. 4-10cm of new snow has covered up a melt freeze crust and/or surface hoar, or a combo of both. The melt freeze crust exists up to approximately 1900m and up to all elevations on solar aspects. The mid-December crust/facet/surface hoar layer is down 40-85cm and is suspected to be reactive in isolated areas, especially where a slab of stiffer snow has consolidated above it.
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.