A complex and unpredictable snowpack exists. Avalanche Canada has released a Special Avalanche Warning for this region. Check out the details here: http://www.avalanche.ca/news/VRHTjCUAADQcpVdL/spaw-150324
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
A Pacific frontal system reaches the coast today and affects the Interior regions tonight through the forecast period. Warm air aloft will invade the region until Friday night with associated freezing levels near 2600 m. A trailing cold front will bring light precipitations and strong ridgetop winds. On Thursday, light precipitation amounts up to 5-15 mm is expected, ridgetop winds strong from the SW and freezing levels rising to 2500 m. On Friday, solar radiation could come into play with a mix of sun and cloud. Freezing levels steady at 2500 m and convective precipitation amounts from 2-8 mm. Unsettled conditions on Saturday will bring light precipitation amounts 5-10 mm, ridgetop winds moderate from the NW and freezing levels dropping to 2000 m.
Avalanche Summary
On Tuesday, the region continued to see numerous natural slab avalanches up to size 2.5 from all aspects and 2000-2500 m in elevation. Natural cornice failures up to size 2 were also reported from southeast aspects near 2600 m. Some of avalanches were failing on a crust layer from mid-March and also stepping down to a deeper crust/facet layer from mid-February. Human-triggered storm slabs and persistent slabs remain a serious concern, especially in steep alpine terrain. Remote triggering slab avalanches from afar also remain a concern. There is currently a Special Avalanche Warning for this region through the forecast period. For more technical information regarding the fatalities last weekend go here: old.avalanche.ca/cac/library/incident-report-database/view/12b2631a-5b7f-4f0e-a2d8-c6f89bfb494d
Snowpack Summary
At higher elevations, 40-60 cm of dense storm snow sits over the mid-March interface which had included crusts, wind affected surfaces, and/or old wind slabs. Anywhere from 25-60 cm of snow sits on the mid- March interface, which has recently been reactive as a storm slab. The mid- February persistent weak interface is now down 80-120 cm and continues to be very reactive, producing very large and destructive avalanches. In exposed terrain, strong SW winds had redistributed the new snow into wind slabs on leeward features. Snow surfaces are reported to be moist below around 1900 m.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
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.