We experienced a significant natural avalanche cycle yesterday. Expect the strong effects of the sun today to destabilize the snowpack again.
Weather Forecast
A strong upper ridge of high pressure is building over much of the province bringing sunny skies and warm temperatures. In our region we will see freezing levels at 1600m, an alpine high of -4 deg C and light ridge top wind. This warming trend will continue with freezing levels forecast to reach 2700m by mid week.
Snowpack Summary
20cm of storm snow has fallen in the last 48hrs, this came in with strong, gusting extreme Southerly winds. Above freezing temps at valley bottom will have created a surface crust below ~1500m. A crust buried 60cm is present on steep solar aspects. Deep PWLs are dormant and buried over 1.5m. Cornices have seen new significant growth.
Avalanche Summary
Yesterday we experienced a significant natural avalanche cycle at Roger's Pass due to heavy snowfall and strong winds. Over 50 avalanches were observed, the largest were sz 3.5s and many ran to the full extent of their runouts. Expect another avalanche cycle again today with warm temps forecast and strong solar radiation.
Confidence
Timing or intensity of solar radiation is uncertain
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.