Regions
Northwest Inland.
Avalanche danger will increase due to the forecast new storm moving into the region.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Strong southwest winds and a couple of cm of new snow overnight with freezing close to valley bottoms. Friday: Extreme southwest winds combined with 5-15 cm of new snow and freezing levels rising rapidly late in the day to 1200 metres. Another 10-15 cm by Saturday morning combined with extreme southwest winds. Freezing levels climbing during the day as the winds continue and another 5-10 cm of new snow falls. Sunday: 5-8 cm of new snow combined with moderate southwest winds and dropping freezing levels.
Avalanche Summary
No new avalanches reported. A few large avalanches up to size 3.0 were remotely triggered in the Kispiox area on Monday on south thru west aspects at 1700-1800 metres. These avalanches were about 80 cm deep and are suspected to have released on the December 25th surface hoar. New storm slabs are expected to develop during the day on Friday.
Snowpack Summary
5-20 cm of settled storm snow sits above a widespread rain crust up to about 1300 m. Recent winds have likely formed wind slabs on lee and cross loaded features. Several buried surface hoar layers have been reported 25-50 cm deep and have given moderate to hard results in snowpack tests. Many areas have hard slabs in the upper snowpack above weak sugary snow near the ground. Triggering a deep persistent slab above this sugary snow will remain a low probability high consequence scenario for some time. Snow profile information from Tuesday at Hankin reports 110cm at treeline with a buried surface hoar layer down 25cm and weak facetted snow down 75 cm as well as depth hoar above the ground. You can see the full report on the MIN.
Problems
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.
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.