Confidence
Fair - Timing or intensity of solar radiation is uncertain on Tuesday
Weather Forecast
Synopsis: The trough that delivered snow through the weekend is starting to weaken, giving way to sunny skies and seasonably cool temperatures.Monday: Freezing Level: 1300 - 1600m; Precipitation: Nil; Wind: Treeline: Light, E | Ridgetop: Light, SETuesday: Freezing Level: 1400 - 1700m; Precipitation: Nil; Wind: Treeline: Light, Variable | Ridgetop: Light, NWWednesday: Freezing Level: 1300m - 1500m; Precipitation: Trace; Wind: Treeline: Light, W | Ridgetop: Light, W
Avalanche Summary
Avalanche activity in the northern portion of the region was limited to natural wet surface sluffs out of steep terrain below treeline. On the Coquihalla a few loose moist avalanches initiated in rock slab start zones ran to size 2.5, terminating in the bottom of the runouts.
Snowpack Summary
The storm produced 10 - 25 cm in the north and around 10 cm in the south. Light to moderate winds generally out of the south formed sensitive wind slabs on isolated terrain features at and above treeline. Below 2000m the new snow rests on a thin melt freeze crust on all aspects, with the exception being north facing terrain features above 1500m. The persistent weak layers from early March and early February continue to be a concern. The March weak layer of wind-scoured crusts, melt-freeze crusts, and/or surface hoar is reported to be down 60 - 100cm. The February crust/facet/surface hoar layer is now deeply buried down 150 - 250cm and may still be triggered by heavy loads like cornice falls or storm slab avalanches in motion. Long fracture propagations resulting in very large avalanches are possible with this layer. Avalanches releasing on these layers may step down to the ground during periods of strong solar radiation or warm spring rain.
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.
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.