Regions
Northwest Inland.
Continued wind, snow and warming has added more stress to buried weak crystals. Conservative terrain selection remains critical.
Confidence
Poor - Due to the number and quality of field observations
Weather Forecast
The active weather pattern will continue as a fairly strong and moist southwest flow remains aimed at the region. Monday: Light to moderate snowfall, intensifying throughout the day / Light southwest winds intensifying to strong values throughout the day / Freezing level at 1000m Monday night and Tuesday: Up to 20cm of snow / Strong southwest winds / Freezing level at 1000m Wednesday: Light to moderate snowfall / Strong southwest winds / Freezing level at 1000m
Avalanche Summary
Avalanche observations have been very limited in recent days. This may speak more to a lack of observations rather than actual conditions. Periods of heavy snow or rain, strong ridge winds, and warming will probably tip off a natural avalanche cycle in parts of the region. We could see wet activity at lower elevations with storm/wind slabs where snow accumulates. There is also potential for deep persistent weaknesses to be overloaded producing isolated very large and deep slides.
Snowpack Summary
Continued snowfall has contributed to ongoing storm slab development. Warm temperatures have promoted rapid slab settlement, while rain has created wet loose surface snow at lower elevations. Southwest winds continue to build slabs on leeward slopes with cornices overhead in exposed treeline and alpine terrain. A crust/ surface hoar combo buried in the middle of January may be around 50-80 cm deep now. In the mid-pack, a crust weakness buried in mid-December seems to be unreactive for the time being. Near the base of the snowpack is the crust-facet combination buried in November that could remain problematic, especially in shallower snowpack areas with heavy loading and warming.
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.
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.