Confidence
Fair - Freezing levels are uncertain on Tuesday
Weather Forecast
A ridge of high pressure intensifies over the region through the forecast period culminating with a significant warm up on Tuesday. Sun interrupted by periods of convective snow flurries continue for Sunday & Monday. Sunday: Freezing level starts near the surface, climbs to around 1900 m and then returns to the surface overnight. Winds calm at all elevations for much of the day. A bit of light east wind develops at upper elevations in the afternoon. Monday: Upper level flow switches from northerly to a more mild southerly in the AM setting the stage for a very warm Tuesday. Freezing levels start near the surface, climb to around 1900m and then return again to the surface; the classic spring diurnal temperature swing. Winds should be light to moderate with an easterly component at lower elevations, switching to a light southerly at ridge top. Tuesday: Looks to offer the most significant warm up the region has seen yet this spring. Freezing levels start near the surface and then climb to 3000 m. Winds should again be light east at lower elevations, light southerly ridge top.
Avalanche Summary
In the Fernie area a skier triggered a size 1.5 avalanche with a 20 cm crown on an E facing slope at 2000 m Friday. Some loose snow activity on a SE facing slope was also reported, but, there is surprisingly little avalanche activity in the region currently.
Snowpack Summary
Mild temperatures in combination with the strong spring sun have helped to settle out the 20 cm from Wednesday's storm which came to rest on the April 4th melt/freeze crust. The new snow was introduced to the sun Friday as skies clear and the temperature at 1600 m climbed to +5. The snow behaved well, very little activity was observed despite the warming. Recent storm snow has added up to 60-120 cm depending on the drainage. Our field team was out in the region Saturday; they were able to find the March 27th interface down around 90cm below the snow surface but test profiles did not produce any results on this layer. Large cornices loom over many lee slopes.
Problems
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.
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.
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.