South Columbia

We've arrived at the tail end of the natural avalanche cycle and now is when it gets tricky. Be particularly conservative between 1500 and 1800m where the storm slab overlies a persistent weak layer that remains sensitive to human triggering.

Low - Timing, track, or intensity of incoming weather system is uncertain on Sunday

The region has been bombarded by the storm chain since December 2nd, but the caboose is in sight. No significant weather is forecast for Friday or Saturday. A rather mundane storm Saturday night will likely be the last pulse before the region enters into a period of high pressure Monday. FRIDAY: No significant precipitation. Freezing level around 1000m, light winds generally out of the west. SATURDAY: Winds ramping up to strong SW during the day. 5 to 15cm expected Saturday night with a freezing level around 800m. SUNDAY: 2 to 8cm of snow, light SW winds, freezing level around 1000m.

Observations have been limited during the storm, especially from alpine elevations. On Monday, Tuesday & Wednesday several natural and human-triggered storm slab avalanches were reported up to size 2.5. These storm slabs were typically 30-60cm thick and occurred on all aspects and elevation bands. A few spooky remotely triggered avalanches to size 2 were reported around 1500m too. Storm slabs are expected to remain sensitive to human-triggering on Friday, but natural activity should taper off now that the storm has ended.

Over the past week, 60-100cm of storm snow has typically accumulated in the region. On Tuesday, rain affected the snow surface as high as 2000m but new snow has subsequently fallen as low as 1500m. The storm slab sits over the early-Dec interface which consists of large surface hoar below 1800m, sun crusts on south-facing slopes, old wind affected surfaces above treeline, and possibly faceted surfaces in some areas. This interface appears to be quite variable throughout the region and information on this layer has been limited, so treat the layer with extra respect until more info is available and give the storm snow extra time to stabilize. Recent strong SW winds have built thick wind slabs in leeward features at alpine and exposed areas at treeline. Deeper in the snowpack, the surface hoar interface from early November has been dormant but still may wake up with heavy loading or smaller avalanches stepping down. On very high northern aspects, a crust/facet interface may be found near the ground.