Regions
Northwest Inland.
While conditions are generally good, extra caution is warranted in windy areas and around convoluted rocky areas with a shallow snowpack.
Confidence
Low - Due to the number of field observations
Weather Forecast
Wednesday: Dry with some clear spells until late in the day. Strong northwesterly winds. Models indicate a weak inversion may set up for Wednesday afternoon with valley temps around -12C and alpine temps more like -5C. Thursday: Light snow, 2-4 cm expected, clearing thorough the day. Winds remaining strong northwesterly. Treeline temps around -12C. Friday: Cold and dry. Light easterly winds. Treeline temps around -20C.
Avalanche Summary
Some natural and skier-triggered avalanche activity was noted from the weekend - it appears as though it can be characterized as small wind slab activity. If you're out in the mountains and see recent avalanches please snap a photo and submit your information to the Mountain Information Network.
Snowpack Summary
The inland region picked up 5 to 15cm of new snow over the weekend accompanied by wind that was initially out of the west, but has since switched to being out of the southeast. This new snow rests on a wide variety of old surfaces including small facets, crusts on solar aspects and stubborn old wind slabs near ridge crest. In protected areas below 1500m the new snow may be sitting on previously formed feathery surface hoar.Two crusts formed near the end of November are found approximately 30 to 50cm below the surface. These crusts are widespread and extend into the alpine. Previous snowpack tests produced hard results on these crusts, but we have not seen any recent information about their sensitivity to triggering. Below these crusts, a well settled mid-pack overlies the late October crust which is down near the ground. The October crust is widespread and has not been reactive to human triggering since the end of November. Average snowpack depths in the region are between 80 and 140cm at treeline, with up to 160cm in the alpine.
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.