Regions
Northwest Inland.
Confidence
Fair - Due to variable snowpack conditions
Weather Forecast
Synopsis: Residual moisture from the last Pacific system will give generally light amounts until Sunday, when a clearing trend develops.Friday: Most likely light snowfall (2-4 cm), but moderate snowfall possible in higher snow areas. Southwest winds 30 km/h. Freezing level around 800 m.Saturday: Light snow, 2-4 cm. Light winds. Freezing level around 600 m.Sunday: Dry and bright. Light northerly winds. Freezing level around 600 m.
Avalanche Summary
Small (size 1) soft slab avalanches could be triggered in response to ski-cutting at treeline on Wednesday; similar activity was reported on Tuesday and Monday from steep wind-loaded features. During the weekend there were reports of natural avalanches up to size 2.5 on north facing slopes following loading from new snow and wind.
Snowpack Summary
Recent storm snow amounts are 30-40 cm in the west of the region and more like 10 cm in the east. Strong southwest winds have formed touchy wind slabs in exposed terrain in the lee of ridges, gully side walls, and behind terrain features. There are a variety of old interfaces now down 60 - 100cm which include facets, crusts and isolated pockets of surface hoar. Recent observations indicate that these weaknesses have bonded fairly well now, but I still suggest digging and testing the snowpack to confirm.A strong mid-pack currently overlies a weak base layer of facets/depth hoar. It is worth noting that the snowpack in general is quite shallow in northern and eastern parts of the region. Triggering the basal weakness may still be possible from thin spots, rocky outcrops or under the weight of larger triggers such as cornice fall.
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.
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.