South Columbia

Convective snowfall and strong southwest winds are expected to quickly form touchy new storm slabs. Seek out supported lines around sheltered lower elevations on Friday.

Thursday night: Flurries bringing 10-15 cm of new snow. Moderate to strong southeast winds shifting to southwest.Friday: Cloudy with continuing flurries and another 5-10 cm of new snow with locally enhanced amounts, continuing overnight. Moderate to strong southwest winds. Freezing level to 1000 metres with alpine high temperatures around -9.Saturday: A mix of sun and cloud with continuing isolated flurries and another trace to 5 cm of new snow, continuing overnight. Light southwest winds. Freezing level to 1000 metres with alpine high temperatures around -9.Sunday: A mix of sun and cloud. Light southwest winds. Freezing level to 1000 metres with alpine high temperatures around -9.

Moderate - Forecast snowfall amounts are uncertain

Reports from Wednesday were limited to small wind slab ski cuts as well as natural and ski cut loose wet releases to size 1.5. Adjacent regions have continued to show isolated small (size 1) ski cut and skier-triggered storm slabs on various aspects in the alpine. These have been failing on recently buried crust and surface hoar layers down 20 -30 cm.Reports from earlier in the week included several small (size 1-1.5) storm slabs that were ski cut and skier-triggered on steeper alpine slopes on a range of aspects. On Saturday there were several reports of solar-triggered cornice and glide crack failures up to size 3 on predominantly south to west aspects at all elevations.Looking forward, avalanche danger will be increasing as strong southeast winds (then southwest) and potentially heavy snowfall form new slabs over Thursday night. These newly formed slabs are likely to be touchy and reactive to human triggering over the near term. The convective nature of forecast snowfall suggests that localized pockets of enhanced precipitation may lead to increased avalanche danger in parts of the region.

Recent light snowfalls (10-20 cm) have been followed by warm daytime temperatures and glimpses of sun, setting up a couple of thin storm snow layers over temperature and sun crusts on south aspects. On shaded aspects at higher elevations, the recent snow has buried a couple of surface hoar layers now found up to 40 cm deep. Mainly small loose dry releases have been observed on the shallowest of these layers (down about 15cm), while the deepest (down 40 cm) has been the failure plane in a few slab avalanches. New snow amounts taper with elevation and below 1900 m, minimal accumulations have buried a supportive crust on all aspects. This crust will likely break down with daytime warming, becoming moist in the afternoon. Deeper persistent weak layers from January and December are generally considered dormant, but could wake up with a surface avalanche stepping down, large cornice fall, or a human trigger in a shallow or variable-depth snowpack area. These layers consist of sun crust, surface hoar and/or facets.