Avalanche Forecast
Issued: Dec 8th, 2016 4:55PM
The alpine rating is Wind Slabs and Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
Moderate - Wind effect is extremely variable
Weather Forecast
Friday: Sunny / Strong to moderate easterly winds diminishing in the afternoon / Strong inversion with a alpine high of -14 C.Saturday: Sunny / Light easterly winds / Alpine high of -15 C.Sunday: Sunny / Light to moderate southwesterly winds / Alpine high of -12 C.
Avalanche Summary
Wind slab avalanches are a big concern in all areas within the region, and could easily step down to the surface hoar layer below. This surface hoar layer may remain reactive to human triggers for a longer period than is common for this region because it is being well preserved my cold temperatures. Last weekend, there were a couple of close calls with people being surprised by the touchiness of the buried surface hoar layer.
Snowpack Summary
The storm from last weekend brought 30-80 cm of cold powder. This new snow has been blown around by the wind - first by southwesterly winds during the storm, then by northerly winds with the onset of arctic air, and now by easterly outflow winds. As a result, expect wind slabs in a wide variety of locations. Unless you're really certain about the recent local wind history, the safest bet is to assume wind slabs could be present on all aspects in exposed alpine, treeline, and even some below treeline locations. The recent snow buried a surface hoar layer, which now lies 60-120 cm in many parts of the region. This layer was reactive during and after the storm and is likely still reactive to human triggers. A thick rain crust exists 20-30 cm below the surface hoar layer, with isolated reports of weak facets (sugary snow) forming above the crust; however, that interface hasn't become a concern as of yet. Treeline snow depths are around 140-200 cm in the Terrace and Stewart areas, but substantially less further north. Concerns in the north are basal weaknesses that may exist in the shallower snowpack areas especially on smooth alpine features like glaciers.
Problems
Wind Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 9th, 2016 2:00PM