Vancouver Island Avalanche Bulletin

Valid until April 4th 2010.

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

Below Treeline (BTL) zones are gaining snowpack once again, still mainly below threshold.

Confidence: Good short term, Precipitation amounts could be 40% higher on West Coast and will continue longer into Saturday before scaling back to showers for the remainder of weekend.

Main Concerns:

• Storm Snow 30 to 90 cm in next 36 hours
• Wind Slab NW through NE Aspects Alpine and Treeline Crossload East & West aspects.
• Cornice Fall, North West North North East East aspects (potential large natural trigger).

Weather:

A surprising amount of precipitation falling mostly as snow continued the wintry trend on the Island this week. The South and West regions saw from 60 to 140mm! The temperatures this past week were generally below freezing except for a few sunny hours. The winds were West to South West with some southerly squalls.

Another winter storm cycle will effect the Island for Thursday night & Friday.  Snow amounts 30cm, to 50 cm in the West, by later Friday and 15 cm as flurries and snow for Saturday except the West 30 cm Saturday, Sunday the snow is forecast as light 5 or 10 with local amounts varying. Freezing levels a 1000m dropping Friday to 500 m and falling further for Sunday to 500 m to Surface for the North and East Isle. Strong winds accompany the storm from the S to SW but turn to West SW Saturday and WNW by Sunday.

Avalanche Activity:

Cornice falls have occurred, triggering slabs.  Wind slabs continue to be sensitive to human triggering and avalanche control. Some steeper terrain shed some loose snow slides with warming earlier this week.

Snowpack:

New storm snow and new wind slab sits on top of recent slabs and new snow over a fairly traditional Maritime base with an old crust that has gained strength.  Solar aspects have a crusts at or near the surface .  North or leeward aspects have much more snow over old crust.  Some sudden planer shears exist in the top 10 to 25 cm in Northerly cooler terrain and at higher elevations.  Moderate to Hard shears at the old crust / newer snow inter phase.  New slabs and snow will build up the potential depth of slabs to more than 60cm.

Cooler temperatures and continued winds could redeposit snow on Saturday or Sunday Mostly in Alpine areas and usually Westerly winds reloading East aspects.

Terrain Discussion: 

Friday: Avoid Avalanche Terrain or choose SIMPLE Avalanche Terrain, Ridge Tops, Heavily forested areas or Wide Valley bottoms.

Saturday & Sunday choose SIMPLE or CHALLENGING Avalanche Terrain with Extra Caution.  Extra Caution for overhead hazards from over head slopes and steeper ground.

Travel Advisory: 

Travel in avalanche terrain is not recommended Friday. On Saturday Sunday avoid COMPLEX Terrain and use Extra Caution in CHALLENGING TERRAIN.  Wide spread Storm snow and localized  wind slab in lee aspects will be fresh on Saturday. Human triggering is LIKELY to PROBABLE in certain terrain during this period.  Consider avoiding large slopes and slopes steeper than 35 degrees.  Cornice or leeward slopes are heavily loaded. Cornice Falls could trigger deeper slabs. 

Outlook:

Friday looks very stormy until late in the day 30 to 50 cm, Saturday looks better but the snow or flurries will continue 10 to 30cm. By later Saturday and into Sunday drying +- 5cm and further cooling to near sea level freezing. Winds are expected from the South  switching to West North West Saturday Lighter and Sunday West North West.