The recent storm snow is expected to remain touchy on Tuesday, especially in wind loaded terrain and on steep slopes where it overlies surface hoar or a crust.
The new snow is expected to be most reactive in wind loaded terrain, especially where it overlies surface hoar and/or a crust. The wind was recently blowing from the SW during the storm but has now shifted to the NW so wind slabs should be expected on most aspects.
Unsettled conditions are expected on Tuesday as Arctic air shifts southward.
Monday Night: Partly cloudy, moderate NW wind, treeline temperature dropping to around -10 C°.
Tuesday: Snow flurries up to 5 cm in the morning, sunny breaks in the afternoon, light to moderate NW wind, treeline high around -8 C°.
Wednesday: A mix of sun and cloud, light variable wind, treeline high around -10 C°.
Thursday: A mix of sun and cloud, light variable wind, treeline high around -6 C°.
On Sunday, ski cutting triggered three size 1 wind slabs on NE aspects at around 2000 m failing on the Jan 14 SH down 20-30 cm. A skier also triggered a size 1 slab on a NE aspect at around 2100 m failing on the newest surface hoar down 15 cm. Some other small skier triggered slabs were reported failing down 25-35 cm on surface hoar and small loose dry avalanches were observed in very steep terrain. This MIN report suggests the new storm snow was becoming reactive immediately on Sunday in wind loaded terrain, even with only 4-6 cm of new snow.
Up to 20 cm of new snow has buried a highly variable snow surface which consists of wind affected surfaces in exposed high elevation terrain, a melt freeze crust at lower elevations and on solar aspects extending into the alpine, and/or widespread surface hoar in sheltered areas which is appears to typically be 5-15 mm but could be as large as 20-30 mm in places.
There are several crusts and surface hoar layers buried 30-60 cm deep. These layers have not been much of a problem recently but may become more reactive with the additional storm loading.
The early December crust/facet persistent weak layer is down 100-200 cm and has been responsible for sporadic avalanche activity throughout the first half of January. The layer has been mainly dormant in the region for the past couple weeks but still remains a concern. See the most recent forecaster blog for more details on this layer.
