Confidence
Poor - Due to limited field observations
Weather Forecast
The region is set to receive an additional 15 - 25 cm of dense snow Monday night and the new snow will be at the mercy of strong to extreme winds out of the W. Snow will continue through Monday delivering an additional 10 cm or so before clearing briefly Tuesday. Freezing levels stay relatively high Monday as they top out around 1500m. Another pineapple (warm/moist) system will move into the region Thursday.
Avalanche Summary
Our field team was out in the region Thursday investigating a slide that ran full path. This avalanche path has a SE facing start zone that had been crossloaded by the recent westerly winds. A wind pillow failed high on the slope triggering a size 3 avalanche with a crown as deep as 85 cm. The likely culprit is a crust/facet combo from mid-December. Very little avalanche activity was reported over the weekend, but it's important to note that On Sunday we received a report of a size 2+ avalanche that was likely human triggered on a sparsely treed slope just below steep rocky terrain in the Smith Basin area. This avalanche had a crown of 100 - 150 cm and likely failed on basal facets near the ground.
Snowpack Summary
The freezing level was as high as 1500m Sunday, as a result, a lot of precipitation that fell on Sunday was rain. It's pretty tough to gauge how much snow the region received as a result. Our field team will be out and about Monday, so, we should have a much better idea of just what happened out there soon. Last week 40-60cm of snow formed soft slabs over a crust/facet/surface hoar combo which has settled remarkably quickly.Deeper in the snowpack, a surface hoar layer buried in early December remains a concern, as avalanches triggered on this layer would be destructive. There may have been releases on this layer post storm but at this time nothing has been reported. It should be noted that basal facets exist in many parts of the region too. Facets sandwiched between two firm layers in the top metre of the snowpack are being monitored in the south-east.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.
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.