South Columbia

Avalanche danger will increase over the day as a warm spring storm builds fresh storm slabs at higher elevations.

Moderate - Forecast snowfall amounts are uncertain

Thursday: Cloudy with wet flurries bringing 5-10 cm of new snow, increasing and cooling overnight. Light southwest winds, becoming strong at ridgetop. Freezing level to 1900 metres with alpine high temperatures around -1.Friday: Cloudy with continuing scattered flurries and another 2-5 cm of new snow, continuing overnight. Moderate to strong southwest winds. Freezing level to 1300 metres with alpine high temperatures around -7.Saturday: Cloudy with flurries bringing another 5-8 cm of new snow. Light southwest winds. Freezing level to 1200 metres with alpine high temperatures around -6.

Reports from Tuesday included two small (size 1) storm slabs that were ski cut and skier-triggered on a steeper east-facing slope in the alpine. The slab depths were just over 20 cm.Monday's reports included a few small (size 1-1.5) skier-triggered wind slabs and storm slabs as well as small ski cut and natural loose dry releases. These all occurred in steeper terrain on a wide range of aspects.On Saturday there were several reports of solar-triggered loose wet avalanches as well as cornice and glide crack failures up to size 3 on predominantly south to west aspects at all elevations.Last Friday there were reports of natural cornices failures up to size 2 on north and northeast facing slopes in the alpine that had little effect on the slopes below.

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.