Sea To Sky

Watch for signs that the recent storm snow is still reactive to triggering.  Slabs will be most reactive in wind loaded terrain features.

Low - Due to the number of field observations on Friday

Light snowfall is expected for Saturday afternoon with 2-5 cm of accumulation. Alpine wind is forecast to be moderate to strong from the northwest and treeline temperatures are expected to be around -10C. A mix of sun and cloud is forecast for Sunday with moderate to strong northeast winds and treeline temperatures around -15C. Sunny conditions are currently forecast for Monday with moderate outflow winds continuing and treeline temperatures falling close to -20C.

On Thursday during the storm, widespread natural storm slab avalanches up to size 1.5 were reported as well as natural sluffing from steep terrain. Most of the slab avalanche activity was described as soft or very soft slabs which were touchy in wind loaded terrain. One remotely triggered avalanche was reported as well as one sympathetically avalanche.  On Friday, explosives triggered numerous storm slabs up to size 2 in the Whistler area.  Slab thickness varied from 20 to 75 cm.  On Saturday, storm slabs remain a concern but wind loaded areas are expected to be the primary area of concern.  Strong alpine winds were from the south at the start of the storm on Thursday and were from the west by the end of the storm.  Winds on Saturday are now coming from the north.  As a result, wind slabs should be expected on all aspects in wind affected terrain.

Between Monday and Friday, 70-100 cm of storm snow accumulated in the region.  Below the new snow from this week lies the Boxing Day interface which consisted of wind affected surfaces, faceted (sugary) snow, or surface hoar. Recent observations suggest the overlying snow is generally well bonded to this interface. Recent weaknesses in the snowpack have been isolated to storm snow interfaces.  Recent strong winds have been from a variety of directions and have been loading leeward and cross loaded features in wind exposed terrain. The mid-December interface is now down 100-150 cm and is generally considered to be stable in the region.