60 - 120 cm of storm snow in the last week and surprisingly little avalanche activity, the sun may change that when it makes it's full appearance on Wednesday. Fat wind loaded features in wind exposed terrain remain suspect, and buried surface hoar at treeline is also a concern.
Cornices have been reported to be especially large. Cornice collapses become likely in warmer temperatures and/or when the sun is out. The weight of a large cornice dropping could be sufficient to trigger a large avalanche on the slope below.
A weak layer of buried surface hoar may be found in parts of the region. There is uncertainty on where this layer is a problem, but it appears to be of highest concern in sheltered terrain features near treeline. Continued rapid loading of the snowpack could re-activate this interface.
50 to 120 cm of storm snow fell between Wednesday Feb 12 and Monday Feb 17. The storm snow is reportedly settling nicely with the continued cold temperatures and the riding has been rediculously good. But, the sun begins to poke through Tuesday and then should be out in full force Wednesday. We're not sure exactly what that is going to do, it may have very little effect, or it may bring on a sharp increase in avalanche activity.
The forecast period is filled with plenty of sun and wind for the foreseeable future.
MONDAY NIGHT: Light to moderate northwest wind, freezing level at valley bottom, no significant precipitation expected.
TUESDAY: Scattered cloud cover at dawn clearing to just a few clouds in the afternoon, moderate northwest wind, freezing level at valley bottom, no significant precipitation expected.
WEDNESDAY: Clear skies, moderate southwest wind, freezing level rising to about 1300 m, no significant precipitation expected.
THURSDAY: Clear skies at dawn with some cloud building in the afternoon, strong southwest wind, freezing level rising to about 1300 m, no significant precipitation expected.
Surprisingly little avalanche activity has been reported. On Sunday explosive control work produced small avalanches running in the upper 20 cm of storm snow.
The weekend storm added 10 to 25 cm of snow to the phenomenal snowfall last week where the wed/thur/fri storm produced 50 (Kakwa) to 100 (Torpy) cm of storm snow under mild temperatures and moderate wind from the south, southwest and southeast. Most of the observations we're seeing suggest that the copious amount of storm snow arrived warm and is settling well in the cooler recent temperatures. The storm snow reportedly has very little slab property, but we're short on observations from more wind effected terrain. This MIN from the Renshaw on Saturday really tells the story.
Last week easy sudden planar shears and widespread storm slabs were observed. The presence of buried surface hoar about 40 to 60 cm below the surface has been confirmed in the Pine Pass, Torpy & Renshaw zones, it may be more widespread throughout the region too.
Below all the recent storm snow there is a thin rain crust from the warm, wet storm on Feb 01. This rain crust has been reported to exist up to treeline elevations around 1700 m. Initially this layer was described as reactive and was the focus of a number of avalanches but no recent activity involving this crust has been reported.
Deep in the the mid-pack there may still be a layer of surface hoar buried in late December. It's gaining strength, but should remain a concern since snowpack tests still demonstrate this layer has the potential to slide, albeit in isolated areas and/or with very large triggers.
