Avalanche Forecast

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

The ridge that has delivered beautiful cold and clear conditions the last few days begins to collapse on Wednesday. High cloud invades the forecast region Wednesday and Thursday ahead of snow that is expected to begin on Thursday night. Total storm amounts look to be on the light side for precipitable water, but, the cold nature of the flow should keep the snow very dry and light. This pattern continues with dribs and drabs of snow expected as we move through the weekend.TUESDAY NIGHT: Freezing level at valley bottom, light variable wind at most elevations with moderate northwest wind at ridgetop, no precipitation expected.WEDNESDAY: Broken cloud cover, freezing level near valley bottom, light variable wind at most elevations with moderate to strong northwest wind at ridgetop, trace of snow possible.THURSDAY: Overcast, freezing level beginning at valley bottom creeping up towards 1000 m in the afternoon, light west/southwest wind, trace of snow possible during the day, 10 to 15 cm likely Thursday night.FRIDAY: Overcast, freezing level near valley bottom, light southwest wind at most elevations with strong southwest wind at ridgetop, 10 to 15 cm of snow.

For the most part, avalanche activity really slowed down Monday. That being said, a size 2 natural wind slab was reported from a NE facing feature at 2600 m. A small (size 1) avalanche was reported from a steep northeast facing slope below treeline at 1300 m, which failed on the surface hoar. Activity on this interface has decreased in the last 48 hours, but this MIN post and this one do a great job of illustrating the nature of this problem which is most prevalent between 1200 and 1800 m. This MIN is a bit older, but it also offers a great visual of this mid and low elevation problem. This interface will likely wake up as storm snow begins to stack up over the weekend.

Saturday delivered warmth and strong to extreme wind out of the west, south, southwest and northwest. This left a crust up to 3 cm thick on steep south and some west facing aspects and redistributed quite a bit of snow into wind slabs in lee features at and above treeline. These wind slabs are probably growing old and tired. In the absence of solar input Wednesday, these are probably only suspect in extreme terrain. The warmth also allowed 25 to 60 cm of snow to continue to consolidate above the mid-January persistent weak layer (PWL). This PWL is made up of large surface hoar that is most prevalent at and below treeline, with enhanced reactivity noted between 1400 and 1800 m. On steep solar aspects this interface presents as a crust, there may be locations where the surface hoar actually sits on the crust.The middle and lower portions of the snowpack are generally well-settled and strong.