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Archived

Avalanche Forecast

Apr 4th, 2017–Apr 5th, 2017
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Kootenay Boundary.

Recently formed wind slabs on high elevation north aspects may remain reactive to triggering. Extra caution is needed around any slopes exposed to large cornices during the heat of the day.

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

WEDNESDAY: Cloudy with isolated flurries / Moderate south wind / Alpine temperature 2 / Freezing level 2000mTHURSDAY: Flurries / moderate to strong south wind / Alpine temperature 3 / Freezing level 2100 mFRIDAY: Flurries / Light to moderate southeast wind / Alpine temperature 3 / Freezing level 2300m

Avalanche Summary

On Sunday, natural sluffing was reported from very steep terrain. Ski cutting was triggering size 1 sluffs with the recent storm snow sliding on a crust. On Saturday, isolated natural storm slab avalanches were reported with thickness of 20 cm. On Wednesday, the main concern is lingering wind slabs in high elevation north facing terrain.

Snowpack Summary

The region is expected to have entered a period of widespread melt-freeze conditions on all aspects and elevations except for high north facing terrain where the surface snow is expected to remain dry. In high elevation terrain, recent strong southwest winds and new snowfall has formed wind slabs in leeward features. At lower elevations and on sun exposed slopes, there are likely several well bonded crust layers in the upper snowpack. A rain crust which was buried on March 21 extends into the alpine is now down 60-80 cm. This crust was the bed surface for several avalanches during the solar cycle at the end of last week. At elevations above around 2100m, the February persistent weak layers may still be lingering down around 100-150cm and weak basal facets may still be lingering in shallow snowpack areas. These deep weak layers appear to have gone dormant but an isolated avalanche or cornice fall still has the potential to step down in the right conditions.

Avalanche Problems

Wind Slabs

Wind slabs have recently formed in north facing terrain at higher elevations and are expected to remain reactive to human triggering on Tuesday.
Use ridges or ribs to avoid pockets of wind loaded snow.Use caution on steep open slopes and unsupported convex rolls

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Cornices

Large cornices are expected to become weak with daytime warming and sustained sun exposure.
Pay attention to overhead hazards like cornices which could trigger a deep persistent slab.Give cornices a wide berth when travelling on or below ridges.

Aspects: North, North East, East, South East.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 2 - 3