Regions
Northwest Coastal.
Recent snowfall and strong winds are creating new problems. Solar inputs on Wednesday may elevate your local hazard. Assess the stability in your riding area before committing to avalanche terrain.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
A ridge of high pressure should keep the North Coast mainly dry on Wednesday. A mix of sun and cloud is expected with freezing levels around 500m and moderate alpine winds from the SW-W. On Thursday, sub-tropical moisture will mix with arctic air resulting in moderate-to-heavy snowfall. Freezing levels should remain at or near valley bottom and alpine winds will become strong-to-extreme. Conditions on Friday should be much the same with heavy snowfall, valley bottom freezing levels, and strong-to-extreme winds.
Avalanche Summary
On Monday, skiers triggered a few size 1 to 1.5 storm slabs. The size 1.5 avalanche released 40cm deep on a NE aspect at 1200m elevation. Sluffing from steep terrain was also reported. Some natural activity was reported on Monday in the NW Inland region. On Wednesday, natural avalanches are possible on sun exposed slopes or recently wind-loaded features. Skier-triggering is likely in wind loaded features and areas where the recent snowfall is settling into a cohesive slab.
Snowpack Summary
30-40cm of new snow has fallen in the last couple days. Strong winds have redistributed this snow in exposed terrain forming winds slabs in leeward features and stripping exposed slopes. The late-January crust is typically down 100-130cm in the south of the region and about half this depth in the north. Tests are indicating that this interface is generally well bonded but isolated avalanches have been reported to have released on this layer recently. The mid-January rain crust and/or surface hoar layer is down over 150cm in the south and has generally become inactive. It may still be a concern in thinner snowpack areas. The November crust/facet combo near the bottom of the snowpack is thought to be generally well bonded. However, this deep and destructive layer is still reported to be reactive in the far north of the region.
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.
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.