Regions
Northwest Inland.
Heavy accumulations are possible as an Arctic front sits over the region. Be prepared to dial back your terrain choices.
Confidence
Moderate - Intensity of incoming weather systems is uncertain
Weather Forecast
FRIDAY: Flurries with accumulations of 5-10 cm / strong west wind / alpine temperatures around -12 C.SATURDAY: Another 5-15 cm of snow / moderate to strong west wind / alpine temperatures around -12 C.SUNDAY: Another 15-30 cm of snow / moderate to strong west wind / alpine temperatures around -10 C.
Avalanche Summary
On Wednesday, evidence of recent natural activity was reported in various parts of the region. Activity included storm slabs up to size 2 on all aspects and dry loose avalanches in steep terrain. On Tuesday, a small storm slab (size 1.5) was triggered by a skier on a southwest aspect at 1250 m. Some persistent slab activity has been reported on the December weak layer over the past few days as well. Several naturally-triggered size 2 persistent slab avalanches failed naturally at 1200 m in the Howsons on Tuesday. A large naturally-triggered size 3 persistent slab avalanche was reported on an east aspect at 1900 m in the Howsons on Monday. Two large remotely triggered avalanches (size 2.5) were reported on north and west aspects around 1600 m north of Kispiox late last week.
Snowpack Summary
Strong winds have built wind slabs in exposed terrain. 30-60 cm of snow lies over a crust and/or weak feathery surface hoar layer buried in mid-January. The crust exists well into the alpine and the surface hoar can be found in sheltered areas in the lower alpine and treeline elevations. Another two crust / surface hoar layers that formed in December are buried 50-80 cm below the surface. These layers produced sudden results in recent snowpack tests and have been the suspected weak layer in recent large remotely (from a distance) triggered avalanches.
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.