Avalanche Forecast

Moderate - Timing, track, or intensity of incoming weather system is uncertain

A series of storm systems will continue to impact the region during the forecast period. The next storm front should arrive late Saturday afternoon or early evening and is expected to yield 20-30cm of snow by Sunday evening. Freezing levels are expected to be 1000-1200m during this period with strong SW winds in the alpine. On Sunday overnight and Monday, another 20-30cm of snow is possible in the highest snowfall areas. Winds will continue to be moderate to strong from the SW and freezing levels should be around 1500m or lower. On Tuesday, similar amounts of precipitation are being forecast but freezing levels could rise to around 2000m.

On Friday, a natural size 3.5 was reported from a steep NE aspect at 2100m.  This was a wind loaded start zone and the slab was 60cm thick.  Ski cutting also produced a size 1 storm slab with a 50cm thick slab.  If we get the forecast snowfall amounts Saturday night, I expect the storm slab to become a widespread problem on Sunday. The slab will likely be very sensitive to human-triggering at all elevations, especially on steep, convex features.

The new overnight snowfall will fall on top of around 40cm of recent storm snow. This storm slab sits over a variety of old surfaces including wind-stripped north aspects, hard wind slabs, facets, sun crusts and/or large-sized surface hoar. Of most immediate concern is a crust/surface hoar interface that is already super-reactive. Reports suggest that the surface hoar exists as high as 2000m and the crust may be found on all aspects. I would not rule out the possibility of weak interfaces at higher elevations, especially sun crusts and facets. Strong SW winds are creating thick wind slabs in leeward features at alpine and treeline elevations. Deeper in the snowpack, surface hoar interfaces that were key players in November have 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.