Northwest Coastal

Fair - Timing, track, or intensity of incoming weather system is uncertain on Saturday

Synopsis: A low pressure system over northwest BC will track south eastward through BC and into Alberta.Tonight: Cloudy with flurries, freezing level around 200 metres, winds from the south light occasionally moderate.Thursday: Cloudy with sunny periods and possible flurries, trace of precipitation, freezing level around 700 metres, winds light, from the west.Friday: Cloudy with flurries, Freezing level around 600 metres, light ridge top winds, occasionally gusting to moderate.Saturday: Cloudy with snow, 15 to 20cm of precipitation, freezing level around 800 metres, ridge top winds, light from the south east.

Not many reports of avalanche activity from Tuesday, which is more likely because of poor weather and visibility, rather than lack of avalanche activity. Large natural avalanche cycle up to size 3's reported on Monday, initiating in the storm slab and running on the early March and Feb. 10th persistent weak layers. With continued loading and wind, rider triggering is definitely possible at this time.

35 to 50 cm of 24 hr. precipitation combined with moderate to strong winds continues to build wind slabs at tree line and above, increasing the depth of the storm slab that now overlies the March persistent weak layer. This persistent weak layer is now buried well over a metre in most parts of the region. 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.A late January/early February crust/facet/surface hoar combo is still showing up in snowpack tests with moderate to hard shear tests. This layer will be with us for a long time, and a slide triggered on this layer would be very large and destructive. Recent warming temperatures will be good for bonding on this layer, but a sudden increase in load, or a large rainfall event could "wake up" this layer and result in very large avalanches.