Regions
Northwest Inland.
Warming and solar radiation will drive the avalanche danger on Monday. Use extra caution in sun-exposed terrain and limit your exposure to large overhead slopes.
Confidence
Low - Freezing levels are uncertain on Monday
Weather Forecast
Sunday night: 3-6mm of precipitation / Moderate southerly winds / Freezing level at about 2000mMonday: Mainly clear / Moderate southerly winds / Freezing level at about 2000mTuesday: 2-5cm of new snow / Moderate southerly winds / Freezing level at 1700mWednesday: Mix of sun and cloud / Light and variable winds / Freezing level at 2300m
Avalanche Summary
No new avalanches have been reported, however it is expected that warm alpine temperatures and sunshine initiated natural activity on steep solar aspects at higher elevations on Sunday.
Snowpack Summary
With the recent temperature inversion, solar and temperature crusts are expected to have formed on sun-exposed slopes, while stiff, stubborn wind slabs linger in lee alpine terrain. Approximately 30-50 cm of storm snow now overlies two crusts that were buried near the end of November. These crusts are widespread and extend into the alpine. Although snowpack tests have previously shown hard results at these crust interfaces, more recent observations have been limited. Below these crusts, a well settled mid-pack overlies the late October crust near the base of the snowpack. This "crust/facet combo" layer is widespread and has been reactive to rider and remote triggers. It also continues to produce sudden snowpack test results. Average snowpack depths now total 80-140 cm at treeline elevations and up to 160 cm in the alpine. (Depths of up to 210 cm have been reported from the Howsons.)
Problems
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.
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.
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.