Spring sun and rising freezing levels may increase the hazard above the forecast. Large, mature cornices are now worth paying close attention to.
Summary
Confidence
Fair - Intensity of incoming weather systems is uncertain
Weather Forecast
Synopsis: A weak frontal system will pass through the area today and will be followed by a short-lived high pressure ridge.Tonight: Cloudy with clear periods, trace of precipitation in the forecast, freezing level at valley bottom, winds light, from the south west.Saturday: Cloudy with snow, 5 to 10cm of precipitation, freezing level around 300 metres, ridge top winds should be light from the south east.Sunday: Cloudy periods, trace of precipitation in the forecast, freezing level around 900 metres, light ridge top winds from the south east.Monday: Cloudy with snow flurries, 10 to 15cm precipitation, freezing level around 600 metres, winds light to moderate from the north.
Avalanche Summary
Continued reports of size 2 and 3 avalanches, initiating in the storm snow and stepping down to the persistent weak layers. There are also reports of loose wet avalanches on steep solar aspects stepping down to the weak layers. With rising freezing levels and spring sunshine, solar aspects may become quite active. Cornices have become quite large in some parts of the forecast region. They are definitely something to watch out for.
Snowpack Summary
The area has received 75 to 150cm of snow over the past 5 to 7 days. The recent storm snow arrived with strong winds and built more wind slabs at tree line and above, increasing the depth of the storm slab that now overlies the March persistent weak layer. In addition, the recent storm snow has fallen on a melt freeze and/or rain crusts that exist in most parts of the region below 1200 metres. This will most likely become reactive on solar aspects when the sun finally comes out.The March weak layer is a combination of hard wind-scoured slab surfaces in exposed terrain, facets and/or surface hoar in sheltered and north aspects, and sun crust on steep solar aspects and is widespread throughout the forecast region. This layer is now buried close to 150cm in most parts of the region. A late January/early February crust/facet/surface hoar combo is still showing up in snowpack tests with moderate to hard shear tests. Recent warming temperatures will be good for bonding around on this layer, but a sudden increase in load, cornice failure, or a large rainfall event could "wake up" this layer and result in a large destructive avalanche.
bcorrigan,
Avalanche Canada
