Vancouver Island Avalanche Bulletin

Valid Until: Thursday 12 January, 2012.

 Confidence:  Good.

Main Concerns: (Avalanche problems)

Wind Slab - In the Alpine only wind slabs will remain sensitive to triggers and can be found in the lees of ridges and in cross loaded features from the West through North all the way around to the South East.

Persistent Slab - Instabilities deeper in the snowpack in the alpine only which date from mid November have significant depths of snow on them where they have not failed in recent storms and could produce large avalanches in those areas. While not widespread they could be triggered from thin slab areas, from heavy triggers such as cornice falls, or from wind slab avalanches stepping down to the deeper weaknesses.

Storm Slab - In the alpine only (above where the rain reached to), on all aspects, significant quantities of storm snow will remain reactive to human trigger on Tuesday.

Weather:

The Island Alps saw 40 to 50mm of water from Friday evening to Monday evening. Only about 10cm of snow came from this precipitation up to about tree line whereas above that rain line it all came as snow to the alpine. Winds were moderate to strong mostly from the South West. The outlook is for a ridge of high pressure to bring a mix of sun and cloud and no precipitation for the forecast period except perhaps for a little later on Thursday. Winds will be generally light and from the North. Freezing levels will be from surface to 700m Tuesday, up to 1000m on Wednesday and up to 1300m on Thursday.

Snow Pack:

The island snowpack varies quite a bit from the east coast to the west and north island and is more complex in the alpine than many are accustomed to seeing on the island. Snow pack conditions described below may or may not apply exactly to the area that you are in so local investigation is important. Up to around tree line the snow pack has been soaked with rain which will now freeze up into a firm crust. Below that are alternating layers of crusts and moist snow. It is a strong snow pack. In the alpine it is a different story. Up to 50cm of storm snow is still settling and has weaknesses within it. Recently formed wind slabs as well as older ones exist on aspects from West through North all the way around to the South East. These will likely be sensitive to human trigger at least for Tuesday if not longer in places. Weak facet/crust layers have been the failure plane for avalanches during previous storms but likely persist in places in the alpine and offer potential for avalanches stepping down to these layers. While these are not widespread and may be difficult to trigger they could produce large avalanches. The mid pack in the alpine is strong.

Avalanche Activity:

Skier triggered avalanche size 1.5 on wind slab in the West Bowl at Mount Cain. See Incident Reports.

Travel Advice:

Travel up to the elevation that has been soaked by rain and formed a crust (around tree line) is generally safe. Caution is recommended regarding the possibility of slipping and falling a long way on hard icy slopes. Above the rain line where snow has fallen rather than rain (generally above tree line) be very aware of where wind has loaded snow and formed slabs and avoid these areas. Be aware that there is the possibility of not only a wind slab avalanche but of that stepping down to weak layers deeper in the snow pack causing larger avalanches.

Prepared by Jan Neuspiel

Tickets go on sale for the Fourth Annual Party for the Bulletin on Wednesday. Don't miss your chance to attend this now legendary event with live music, silent auction and lots of fun. This is the thing that keeps your source of avalanche info going so come out in support. It all happens at the Riding Fool Hostel in Cumberland on Friday 27 January. More info here.