Regions
South Coast Inland.
Danger ratings are forecast for the south of the region where precipitation amounts and freezing levels are predicted to be higher Friday night through Saturday.
Confidence
Low - Forecast snowfall amounts are uncertain on Saturday
Weather Forecast
FRIDAY NIGHT: Snow, accumulation 10-15 cm in the south and 5-10cm in the north / Moderate to strong southwest wind / Alpine temperature -3C / Freezing level 900mSATURDAY: Snow, accumulation 15-25 cm in the south and 5-10 cm in the north / Moderate to strong southwest wind / Alpine temperature -1 C / freezing level 1500-2000mSUNDAY: Mostly cloudy with sunny breaks / Light to moderate northwest wind / Alpine temperature -5 C / Freezing level 700 mMONDAY: Mix of sun and cloud / Light west wind / Alpine temperature -4 C
Avalanche Summary
Reports are limited, but no avalanches have been reported in past few days.
Snowpack Summary
15-30 cm of recent new snow covering what is reported to be a widespread weak layer of feathery surface hoar. Below this, about 30 cm of recent storm snow sits on a melt-freeze crust below around 1800 m. Reports are limited, but they suggest that the snow is bonding well to the crust. Expect the deepest deposits of storm snow to be in lee and cross-loaded terrain features.In the north portion of the region and possibly the far south, a weak layer of facets and surface hoar lies below all this storm snow, around 100 to 150 cm deep. The weak layer appears most prominent around treeline, up to 2000 m. There has not been reports of avalanche activity on this layer for the past week. Although this layer is likely gaining strength, field observations show that slab avalanches remain possible on this layer where it exists.Near the base of the snowpack, a crust exists with weak and sugary facets beneath it. This could potentially still be of concern in high north-facing aspects where the snowpack rests on very smooth ground cover. A very large trigger, such as a cornice fall, would likely be needed to form an avalanche on this layer.
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.