Regions
Northwest Inland.
High danger may overstate things Thursday if the expected snow amounts come through less than anticipated. However, strong winds will still increase danger rapidly in exposed areas.
Confidence
Poor - Timing, track, or intensity of incoming weather is uncertain for the entire period
Weather Forecast
Synopsis: A Pineapple Express to the south of the region will spill some moisture over into this region starting Thursday. Note, poor confidence in snowfall amounts at this time.Thursday: Moderate snowfall, with the potential for locally heavy amounts. 10-20 cm. Freezing level rising to around 1000 m in the afternoon. Winds southwest 35 km/h becoming 60 km/h in the afternoon/evening.Friday: Most likely light, but moderate snowfall possible. Southwest winds 30 km/h. Freezing level around 800 m.Saturday: Flurries. Winds becoming light. Freezing level around 600 m.
Avalanche Summary
Small (size 1) soft slab avalanches could be triggered in response to ski-cutting at treeline on Tuesday and similar activity was reported 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
A new sun crust has formed on steeper solar aspects. In shady areas there is 40-60 cm of well settled storm snow. Strong southwest winds formed touchy wind slabs in exposed terrain in lee of ridges, in gullies, 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.