Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Regions
South Rockies.
Confidence
Fair - Timing or intensity of solar radiation is uncertain on Tuesday
Weather Forecast
Overview: A ridge of high pressure will bring dry conditions to the region on Tuesday. A frontal system will bring moderate snowfall on Wednesday before the dry ridge rebuilds on Thursday.Tuesday: Generally clear skies / Light to moderate northwest winds / Freezing level at 1500mWednesday: 10-15cm of snow / Moderate to strong southwest winds / Freezing level at 1400mThursday: Mix of sun and cloud with light flurries / Moderate northwest winds / Freezing level at 600m
Avalanche Summary
In recent days avalanche observations have been very limited, likely because of inclement weather. There was, however, a report of a size 1.5 human triggered slab avalanche in the Harvey Pass area. See our Incident Report Database for more details.
Snowpack Summary
On Sunday up to 40cm of snow fell at higher elevations and was blown by strong winds into much deeper deposits in lee terrain. Snowpack tests suggest there are still likely weaknesses on a graupel layer near the base of the storm snow. The recent accumulations overlie hard rain crusts which exist on all aspects below 2000m and on solar aspects in the alpine. North of Sparwood and in the Crow's Nest Pass area the buried crust seems more specific to previously sun-exposed slopes. Rain below about 1700m continued to saturate the snowpack, and surfaces may now exist as a hard refrozen crust if temperatures dip below freezing.The deep facet/crust persistent weakness buried at the beginning of February, now down up to 150cm, is still producing sudden results in snowpack tests. I would be very leery of any slopes that have not already avalanched as any activity at this interface would be large and destructive. Triggering will become more likely with forecast clearing and solar radiation.Cornices have also become large and unstable.
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.
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.