Regions
South Coast Inland.
The new snow at higher elevations may become reactive with the first hit of sunshine. Natural slab and loose dry avalanches are likely.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
Friday: A mix of sun and cloud with alpine temperatures near -7 and freezing levels dropping to valley bottom. Ridgetop winds light from the northeast.Saturday: Mostly sunny. Alpine temperatures near -5 and freezing levels at valley bottom. Ridgetop winds light from the West.Sunday: A mix of sun and cloud. Alpine temperatures -8 and freezing levels rising to 800 m.
Avalanche Summary
On Thursday, several loose wet avalanches and glide releases up to size 2.5 were reported from the the southern part of the region. No new reports from the north.
Snowpack Summary
Recent snowfall totals are highly variable. In the south, up to 40 cm of new snow fell bringing the alpine totals up to 60 cm since the weekend. In the north, new snow totals are half that and rapidly decreasing below 1800m. This new snow sits on old wind slabs in alpine locations and has buried a crust at treeline. At lower treeline and below elevations, warm temperatures and rain have saturated the upper snowpack. A solid surface crust will likely form with forecast cooler temperatures. This new snow adds to the 80-150 cm mid pack that sits above the mid- January crust, which generally shows signs of bonding to the overlying snow; however, I would remain suspect of this deeper layer as the snowpack adjusts to the new load. Large, looming cornices exist, they are fragile and demand respect.
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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.