Vancouver Island Avalanche Bulletin

Valid for end of season period.

DANGER RATINGS (Make sure you understand the danger level meanings)

Confidence: The forecast accuracy is diminished his time of year due to lack of field information. Our forecast product relies on weather data, visual scans with high power binoculars,  and weekly visits to the mountains. 

Weather can spike the Hazard 'for a period of time' ; such as  Sun, Rain, Snow, Wind, light cloud cover during day, which causes a green house effect.  Further warming problems develop when cloud over night can prevent freezing of the surface and high prolonged above freezing temperatures persist making the snowpack Slushy or ISO THERMAL.

• Wet loose surface avalanches. (Potential Natural Trigger)
• If storms materialize * Wind Slab in Alpine, on leeward aspects West, North and to East. (North and West Isle)
• Cornice Fall above 1700 m, North West North North East East aspects (potential large natural trigger).
• Wet New and Old slab and or deeper wet slab potentially stepping down into February or January layers.

Avalanche Behavior in Spring:  A couple of things do occur in the spring that are worth mentioning:

1. Change happens Fast:    One minute a supportive crust the next slush. Many scenarios are possible but expect rapid change in stability as the temperature and other localized factors influence.
2. Entrainment:      Snow once Isothermal can be picked up by the original starting zone snow or cornice piece, this is called 'Entrainment'. Entrainment potential increases as the snow looses strength and this process greatly increases the volume of snow in involved in an avalanche. 
3. Distance avalanches travel:      Higher water content snow in spring avalanches can exceed normal run outs. The path the debris follow is typically more confined and follows 'Drainage' type features and does not usually travel as fast.
4. Packs a punch:     High water content snow and older deeper layers of the snowpack will typically have a higher water content or density. This means that the debris is heavier, will likely be much harder to dig if it sets up hard (normal).
5. Random Natural triggers:     Avalanche activity may taper right off and lull you into over confidence and then wham! The random large natural trigger cornice or old slab lets go and more snow often releases with it.

Weather:

Avalanche Activity:

Terrain Discussion: 

Travel Advisory: If you are deeper than your ankles in slush the snow is not to be trusted.

General Spring time advice: Watch the temperatures and sun and back out before the heat sets in. This time of year the sun, rain and above freezing temperatures are common. This brings the possibility of rapid temperature increases and changes in the snow cover. Natural triggers such as cornice, tree bombs could be active at this time. Human Triggering is unlikely when frozen and Possible to Probable if sudden or prolonged melting or rain occurs. Caution with Travel on or below cornices.   Caution Solar aspects during day warming. Keep good track of your surroundings as large natural triggers could start slides high above you or trigger and propagate  horizontally.

Outlook:

Spring and winter mixing, spring wins in the end.