The Bottom Line: Strong winds will drift the new snow into thick slabs. In places these are sitting on a hard, refrozen crust, and may not bond well. Identify wind slabs by their shape, texture, and feel. Look to avoid these slabs on steep slopes.
Snow and Avalanche Discussion
An observer in the Gallagher Head Lake area on Saturday found a stout rain crust up to his high point at 6,500ft. This is good news for the persistent slab problem in this area. Uncertainty remains as to how high and thick this melt freeze crust exists in the greater eastern slopes. A very deep avalanche was observed to have peeled away from a convex roll on a Southeast slope at 6,600ft near Mt. Daniel. This appears to be at least a day or two old.
Large avalanche off a peak near Mt. Daniel observed on 1/5.
Avalanche Problems
Wind Slabs
With strong winds, fresh snow, and cool temperatures, wind slabs will be the main concern for Sunday. Use extra caution at upper elevations on leeward, wind loaded slopes steeper than 35 degrees. Look for fresh drifts and areas of variable snow depth as indicators that you could trigger a wind slab avalanche. Use surface texture and feel to help identify where you can find these on the slopes. Steer around thickly pillowed areas and convex rolls where the slopes steepen. Use small, inconsequential test slopes to clue you in to how well the new snow is bonded. In many locations, the new snow may be sitting over a firm, refrozen crust and may not be well bonded.
Aspects:
All aspects.
Elevations:
Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 2
Persistent Slabs
On the 31st, a highly reactive layer of buried surface hoar was found above Leavenworth in the Icicle Creek drainage. The instability was obvious above 6,400ft where shooting cracks ran long distances. A number of avalanches were triggered from up to 200ft away while walking on a ridgeline. Activity appeared to be mainly on North through Southeast aspects. These avalanches were surprising in how widely they broke across the slopes. This layer is likely much less reactive at this point, but surface hoar is still being found from 1.5 to 3 feet down from the surface in the region. Fresh snow and wind drifting may stress it again.
On the 5th, an observer near Gallagher Head Lake found this layer down 18" at 6,500ft, but a stout rain crust was found over the top of it. At the uppermost elevations and further north in the zone, this rain crust may not exist, so the layer may still be in play. At elevations below about 6,000ft, water has percolated through much of the upper snowpack and refrozen, so this layer is less of a concern. Be observant of shooting cracks or collapsing, or the absence of a stout rain crust about a foot down.
