Regions
Kootenay Boundary.
Rising temperatures and Solar radiation will play a leading role in the avalanche hazard in the coming days. Pay special attention to large ripe cornices !
Confidence
Fair - Freezing levels are uncertain
Weather Forecast
Synopsis: The Pineapple express that plowed its way across the province in the last few days has moved south and east leaving us with a high pressure ridge for the next few days.Tonight: Cloudy with some clearing, freezing level should drop to valley bottom. ridge top winds light to moderate from the north west.Tuesday: Mix of sun and clouds, no precipitation in the forecast, light to moderate winds at ridge tops, freezing level climbs to 1400m, and possibly above.Wednesday: Sunny with cloudy periods, no precipitation in the forecast, freezing level rising to 2000m. winds from the south west, light to moderate.Thursday: Sunny with cloudy periods, possibility of flurries, freezing level rising to 1900m. Light ridge top winds.
Avalanche Summary
Cool temperatures in the next 24 hrs. will slow down the amount of natural avalanche activity, but temperatures are forecast to rise later in the week. We are still receiving reports of large avalanches having run in the past 24 hrs., and the previously mentioned weak layers will be with us for the foreseeable future. There is still the possibility for a rider or skier to trigger an avalanche that might step down to any of the persistent weak layers in this years snow pack and produce a very large and destructive avalanche. Cornices should also be on the radar now. As temperatures rise the chance of a cornice failure producing a large avalanche will go up..
Snowpack Summary
Warm temperatures have promoted rapid settling of the recent storm snow into a slab that now sits above a variety of old surfaces. There are buried facets on north aspects and sun crust on many south facing slopes. Rain up to 1800m has saturated the upper snowpack in some parts of the forecast area. At elevations above the freezing level strong SW winds have have formed winds slabs in lee features. 3 persistent weak layers are now buried in the snowpack, A January 28th layer of surface hoar, facets and crusts, a Feb.10th layer of surface hoar, facets and crusts, and the March 2nd layer of surface hoar, facets and crusts. Of these layers, the Feb. 10th layer appears to still be problematic, with field reports still indicating easy and sudden planar shears on this layer, especially on north aspects. The most recent weak layer, March 2nd, will be on the radar for a while as we wait for it to bond.
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
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.