Avalanche Forecast

Issued: Mar 22nd, 2021 2:00AM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Cornices and Storm Slabs.

Ryan Shelly, VIAC

Vancouver Island.

Size 2 avalanche (including a partial burial) Mt Cokely, initiated Saturday March 20 on North Facing Convex feature at higher elevation. Additional reports (South Island) of unstable snow and new storm snow in excess of 30cm.

Summary

Past Weather

A series of stormy and relatively cool winter days have deposited new snow on a variety of snow surfaces throughout Vancouver Island.

Weather Forecast

Monday: Less than 1cm Snow throughout forecast area, Winds Moderate from the NW shifting to Light NW winds in late afternoon, Freezing level 1,050MTuesday: Less than 2cm snow throughout forecast area, Winds Moderate from the SW shifting to Light SW winds in afternoon, Freezing level 1,000MWednesday: 10cm snow to 20cm Snow. Winds Moderate from the NW (gusting to Strong), Freezing level 1,050M.

Terrain Advice

Practice patience and allow time for new storm instabilities to stabilize prior to committing to any steep terrain.Plan routes and choose terrain that is low angle and supportive as you begin to venture into unmodified and uncontrolled snowpack and terrain.Identify and avoid travel either above or below cornice features.Adjust travel plans to ensure avoidance of slopes during warming and where rain events may occur at the Below Treeline elevation band over weekend.

Snowpack Summary

Mt Washington reporting a total storm snow accumulation of 50cm. Other areas have received similar amounts (30+ cm's) of snowfall over this past weekend's storm event. The upper snowpack at lower elevation (Below Treeline) was subjected to a melt freeze event on weekend however higher elevation bands (upper Treeline and Alpine) have 2+ feet of soft powder snow conditions resting on top of firm snow.

Snowpack Details

Surface: 50+ cm of new powder snow conditions at Treeline and Alpine elevation bands
Upper: Well bonded and dense moisture laden snowpack
Mid: Well bonded midpack
Lower: well settled and dense

Confidence

High - Weather models in agreement. Sufficient Professional and public observations. Thank you Faron, Evan and Derek for your MIN reports!

Problems

Cornices

Very large cornices exist and continued snowfall, wind and high humidity continue to promote cornice growth. Cornice failures have the potential to over load the snowpack and trigger both new snow instabilities as well deeper instabilities. Expect the new growth to be fragile and when temperatures and freezing levels rise become suspected triggers in bigger avalanche events. Location: Many aspects at ridge top in the Alpine and Tree line. Possibility: Triggering of this avalanche problem is likely to very likely from light loads such as skiers/snowmobilers. Natural avalanches are possible to likely. Size: If triggered expect these avalanches to be large size 2, on isolated terrain features very large, size 3

Likelihood

Possible

Expected Size

1 - 1

Storm Slabs

This new avalanche problem will develop Friday in areas that receive snow in excess of 20cm- sensitivity to triggering will increase over the course of the storm event. On isolated Alpine terrain expect this new snow to overly buried surface hoar. On solar aspects, expect the storm snow to overlie a melt freeze crust. Location: All aspects, Alpine and Tree line. Below tree line hazard is from above. Possibility: Triggering of this avalanche problem is likely to very likely from light loads such as skiers/snowmobilers. Natural avalanches are possible to likely. Size: If triggered expect these avalanches to be large size 2 (by Friday), on isolated terrain features very large, size 3.

Likelihood

Possible

Expected Size

1 - 1

Valid until: Mar 23rd, 2021 2:00AM