Heading into a stable weather pattern to start the new year with a gradual rise in temperature. Consider the potential to trigger persistent slabs as the recent storm snow starts to finally settle and consolidate more rapidly.
Summary
Confidence
Moderate - Due to the number of field observations
Weather Forecast
SUNDAY: Mix of sun and cloud / Light to moderate northwest wind / Alpine temperature -8MONDAY: Mix of sun and cloud / Light to moderate west wind / Alpine temperature -5 TUESDAY: Mix of sun and cloud / Light northwest wind / Alpine temperature -3 with possibility of a temperature inversion
Avalanche Summary
Recent reports continue to show both natural and human triggered loose dry avalanches in steep terrain to size 1 in areas that have not been affected by wind. Additionally isolated wind slab avalanches have been reported in the alpine to size 1. Expect continued potential for triggering loose dry avalanches in steep terrain and consider the potential to trigger persistent slabs where last week's storm snow has settled into a cohesive slab.
Snowpack Summary
20-40 cm low density new snow has accumulated and buried a recently formed layer of weak feathery surface hoar and/or sugary facets. Another layer buried mid-December that consists of surface hoar, sun crust and/or sugary facets is down approximately 40-70cm. The bond at this old snow interface is of critical importance where the overlying storm snow has consolidated into a slab. The most concerning areas are those that saw pronounced surface hoar development before the storm, such as sheltered areas at and below treeline and any area where the surface hoar may have formed on top of a sun crust. Recent snowpack tests show wide ranging reactivity on this layer but suggest that it may be most reactive on northerly aspects. A rain crust that formed in late November is now buried 70-110cm deep. Recent reports show this layer to be unreactive at this time.
mbender,
Avalanche Canada
