Avalanche Forecast

Issued: Apr 6th, 2017 3:55PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Wind Slabs, Cornices and Loose Wet.

mbender, Avalanche Canada

Kootenay Boundary.

There is the possibility that locally higher than forecast precipitation may fall in certain parts of the region. In the case of higher than forecast precipitation, the avalanche danger may be higher than indicated.

Summary

Confidence

Low - Due to the number of field observations

Weather Forecast

FRIDAY: Flurries, accumulation 10-15cm / Moderate to strong southwest wind / Alpine temperature -2 / Freezing level 1500mSATURDAY: Mainly cloudy with isolated flurries, accumulation 5-10cm / Moderate southwest wind / Alpine temperature -4 / Freezing level 1300mSUNDAY: Mix of sun and cloud / Light northwest wind / Alpine temperature -5 / Freezing level 1200m

Avalanche Summary

On Friday, the main concern is lingering wind slabs in high elevation north facing terrain and the possibility of large overhanging cornices releasing with overall warm temperatures over the coming days.

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 moist or wet snow sitting on top of 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.

Problems

Wind Slabs

Wind slabs have recently formed in north facing terrain at higher elevations and are expected to remain reactive to human triggering.

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/or sustained sun exposure.

Pay attention to overhead hazards like cornices which could trigger a deeper buried weak layer.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

Loose Wet

The weight of a smaller loose wet avalanche could trigger deeper weak layers at upper elevations

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.If triggered loose wet avalanches may step down to deeper layers resulting in larger avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Apr 7th, 2017 2:00PM