Regions
Northwest Coastal.
Forecast new snow and wind will continue to add to the load of storm snow. Conservative terrain selection is recommended during the stormy weekend.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain on Sunday
Weather Forecast
10-15 cm of new snow is forecast overnight with strong southerly winds and freezing levels around 200 metres. Another 5-10 cm is forecast during the day Sunday with moderate westerly winds. The south of the region around Kitimat may see enhanced snowfall as the low pressure moves onshore in the central coast. Continued light snow on Monday with slightly higher freezing levels near 500 metres. Tuesday mostly flurries with cooler temperatures and a chance of broken skies.
Avalanche Summary
No new avalanches reported. Extensive wind effect reported in the alpine and at treeline.
Snowpack Summary
New snow continues to slowly build the load above buried weak layers. There is 15-25 cm above the December 17th (151217 SH) surface hoar, and 25-40 cm above the December 14th (151214 SH). At this time, the new snow continues to come in cold and dry and may not have the load needed to settle into a cohesive slab above these weak layers. The early December layer buried on the 1st or 2nd (151201 SH) is now down a metre or so depending on your area. This layers distribution is variable. In some areas, this layer may be sensitive to human triggering and wide propagations while in other areas it is non-existent or has gained significant strength. Most of this information is coming from the Shames area or from commercial operations near Terrace. Conditions may be different close to Kitimat, where it looks like recent snowfall amounts may be a bit higher and temperatures a bit warmer. The north of the region has a shallow early season snowpack and may have weak facetted crystals near the ground due to cold temperatures over a thin snowpack.
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.