Vancouver Island Avalanche Bulletin

There are a few tickets still available for the  Fourth Annual Party for the Bulletin. The event will sell out this year again so don't miss your chance to attend this now legendary party 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.

Valid Until: Saturday 28 January, 2012.

Confidence:  Fair. Uncertainty about intensity, timing and freezing levels of coming system. If this system comes in sooner on Saturday, Hazard levels will rise earlier. Watch freezing levels and be aware that when precipitation comes as snow load increases significantly with wind transport.

Main Concerns: (Avalanche problems)

Wind Slab - Strong to very strong winds have created widespread and touchy wind slabs mostly on east through north west aspects from our recent large storms. These slabs remain sensitive to human trigger in the alpine and at tree line and could produce large avalanches particularly in the alpine where slabs are stiff. With wind changing direction to west and north west on Thursday new wind slab has formed in the alpine and at tree line on east through south east aspects. More new wind slabs will form in the alpine and possibly at tree line (depending on how high freezing levels rise) from moderate to strong west to south west winds on Saturday and Sunday.

Storm Slab - Variations in temperature during the past storms have resulted in weaknesses within the storm snow which remain triggerable by humans on all aspects at tree line and in the alpine. New storm slab will form with the coming system on Saturday/Sunday in the alpine and at tree line on all aspects.

Cornices - Great quantities of snow and very strong winds have built cornices which are a hazard in their own right but can also act as very heavy triggers for large avalanches.

Weather:

The island Alps received from 125 to 165cm of snow since Sunday. The snow came with winds that exceeded 100kph at times and came from the SW through to SE. Freezing levels varied but stayed mostly at or below 1000m for the most part except for a rise to tree line for about four hours on Tuesday evening. A ridge of high pressure has shifted winds around to the NW and dropped temperatures since Thursday. The outlook is as follows:

Friday: Mix of sun and cloud. Trace amounts of snow. Moderate west to south westerly winds, freezing levels around 500m.

Saturday: Our next system approaches starting later in the day and giving about 30mm of water by midnight. This will come either as rain or as snow depending on elevations and how high freezing levels rise from 500m to possibly as high as 1800m overnight. Moderate to strong SW winds.

Sunday: 5-35mm of precipitation (most on the west island, least on the north) will come as rain or snow depending on elevation and rate of freezing level drop from as high as 1800m back down to 800-1200m. MOderate to strong west to south west winds.

Snow Pack:

Great quantities of new snow and very strong winds have created wind slab mostly on East through to Northwest aspects. Variations in temperature during the storms have created weaknesses within the storm snow. These remained touchy in tests on Wednesday and Thursday delivering easy results. A crust was formed when freezing levels rose to tree line on Tuesday evening. With cold temperatures since, this crust has thickened to support a skier by Friday. At tree line the crust is less than 1cm thick and it does not reach to the alpine. There is 10-25cm of new snow on top of this crust depending on location. This snow is not bonding well to the crust and has been moved by north and north west wind to create new wind slabs on south to south east aspects. The mid and lower pack are strong.

Avalanche Activity:

A widespread natural avalanche cycle during the past storms with avalanches to size two observed.

Travel Advisory:

In the alpine and at tree line be aware of deep and stiff winds slabs which are sensitive to the load of a human. Stay out of wind affected areas and be aware of what is above you. Winds shifting to west and north west on Thursday have also created new wind slab on east through south east aspects. Also be aware that even where there is not wind slab, instabilities exist withing the storm snow which remain triggerable by humans. Sticking to lower angled and supported terrain in the alpine and at tree line is recommended. Be aware that cornices are a hazard in their own right but can also act as very heavy triggers for large avalanches. Cornice failure is very difficult to predict. Give them a wide berth. Watch the approach of our next system on Saturday. If it arrives earlier than forecast hazard levels will rise sooner. New wind and storm slab will form with this system. Stay out of avalanche terrain on Sunday.

Prepared by Jan Neuspiel