New snow totals are uncertain in this weather pattern. Danger ratings are based on 5-15 cm of new snow. If snowfall amounts are greater than 20 cm, the danger is CONSIDERABLE and time to dial back your terrain use while avoiding overhead hazard.
Confidence
Low - Forecast snowfall amounts are uncertain on Sunday
Weather Forecast
Sunday: 5-10cm of snow Saturday overnight to Sunday with another 5-10 cm possible during the day / Moderate gusting strong west winds / Freezing level at 1500mMonday: Mainly cloudy with isolated flurries / Light north westerly winds / Freezing level at 1200mTuesday: Isolated flurries (5cm possible) / Light to moderate south westerly winds / Freezing level 1000m.
Avalanche Summary
On Saturday we received reports of a skier triggered size 1.5 avalanche near Whistler on a north west aspect around 2100m.On Friday ski cutting produced several size 1 soft slabs on immediate down wind (lee) features. Explosives control on Thursday and Friday triggered cornices at ridge crests, mostly size 1.5 - 2.
Snowpack Summary
Over the past two days 7-12 cm of new snow has fallen as temperatures warmed up to +2 at tree line on Saturday afternoon. Winds, however, were strong to extreme from the south, creating fresh wind slabs in exposed downwind (lee) terrain. At lower treeline and below, generally light amounts of snow or rain now overlie a melt-freeze crust which formed during last Monday's warm storm. The new snow adds to the 170cm of snow that fell during the last few weeks of January. These series of storms were accompanied by strong to extreme winds which resulted in extensive scouring and impressive cornice growth in upper elevation terrain. These accumulations sit on a crust from mid-January which generally shows signs of bonding to the overlying snow; however, it has the potential to "wake-up" with a large trigger such as a cornice fall.Below this, the snowpack is thought to be generally strong and well-settled.
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.