Continued snow and wind over the past few days will keep the avalanche danger elevated at upper elevations.
Confidence
Moderate - Forecast snowfall amounts are uncertain on Saturday
Weather Forecast
SATURDAY: Flurries, accumulation 5-10cm / Moderate southwest wind / Alpine temperature -5 / Freezing level 1400mSUNDAY: Mix of sun and cloud / Light to moderate south wind / Alpine temperature -6 / Freezing level 1300mMONDAY: Flurries / Light southwest wind / Alpine temperature -6 / Freezing level 1300m
Avalanche Summary
Reports from Wednesday and Thursday include explosives triggered storm slabs running size 1.5 - 2, 25-30cm deep. On Monday a few natural cornice releases to size 2.5 were observed running to the bottom of their run outs entraining loose snow only. On Saturday, expect newly formed wind slabs to be reactive to human triggering.
Snowpack Summary
30-50cm of new snow at upper elevations sits on widespread melt-freeze crusts that exist on all aspects and elevations except for high elevation north facing terrain. On all aspects below 2000 m and higher on sun exposed slopes, there may be multiple crust layers in the upper snowpack. Moderate to strong alpine wind from the south will have redistributed the new snow and formed additional wind slabs in the alpine and at tree line. Large overhanging cornices exist primarily on north aspects in the alpine.
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.