Triggering large avalanches remains possible. Carefully evaluate conditions before venturing into bigger terrain.
Confidence
Moderate - Intensity of incoming weather systems is uncertain on Saturday
Weather Forecast
FRIDAY: Mainly cloudy with light snow bringing as much as 5cm throughout the day and another 5cm overnight. Freezing levels reaching 1700m and light southerly winds. SATURDAY: Mainly cloudy with continued light snowfall bringing another 1-3cm of accumulation. Freezing levels should drop to 1600m and winds are expected to be light from the southwest. SUNDAY: Mainly cloudy with continued light snowfall bringing another 1-3cm of accumulation. Freezing levels should drop to 1600m and winds are expected to be light from the southwest.
Avalanche Summary
Reports from Wednesday include limited results with explosives control producing only one Size 2.5 persistent slab avalanche releasing on the early-January surface hoar down 100cm in a lower elevation start zone where previous surface hoar growth was prevalent.
Snowpack Summary
A supportive surface crust is likely in most places aside from shaded aspects at treeline elevations, and lower elevations that are under melt-freeze conditions. New surface hoar could be covered by a skiff of fresh snow. This recently buried surface hoar is likely larger on sheltered shady slopes, but could be more sensitive where it is sitting on a crust. Recent snowpack tests have been producing easy to hard results in the top 25-35cm on storm snow weaknesses as well as buried surface hoar and crusts with associated facets. Avalanche professionals are still monitoring the persistent weakness buried early January, which is now down 80-120 cm. In most places it is no longer sensitive to light triggers. However, in specific locations it still produces hard, but sudden results in snowpack tests.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.