Avalanche Forecast

Issued: Mar 28th, 2016 8:37AM

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

pmarshall, Avalanche Canada

South Columbia.

Expect avalanche danger to rise during the day, particularly on sun-exposed slopes. Plan to start your day early and move away from large sun drenched slopes during the heat of the day.

Summary

Confidence

Moderate

Weather Forecast

WEATHER SUMMARY: It will be a sunny and warm week! Temperatures will steadily climb each day with the freezing level reaching at least 2500 m by Thursday (treeline temps near +5). Ridge winds should be generally light from the NW-NE.

Avalanche Summary

Avalanche activity was minimal on Sunday. Only minor loose wet sluffing was observed, and one natural cornice fall was also reported. On Saturday there was a report of a natural cornice fall that triggered a size 3 persistent slab on a steep, rocky, north-facing slope. On Friday, just outside the northern extent of the region, there was a report of a very large (size 4) persistent slab on a large south-facing slope that was triggered by new snow loading. This avalanche likely failed on the late February interface.

Snowpack Summary

Approximately 5-10 cm of snow fell on Sunday, which will probably be sun-affected on solar aspects and wind-affected in exposed terrain from forecast northerly winds. Approximately 40-50 cm of settled storm snow sits on a melt-freeze crust buried on Mar. 22. The late February persistent weak layer is an aspect dependant mix of surface hoar, facets and/or a thick crust down around 60-110 cm below the snow surface. Commercial operators continue to see hard sudden planar results in snowpack tests, which suggests that wide fracture propagations are possible. Cornices continue to be described as large and fragile. Expect loose wet avalanches and natural cornice falls with strong solar radiation and significant warming this week.

Problems

Storm Slabs

Strong sunshine and warming could make recent storm slabs sensitive to triggering, particularly on southerly aspects where new snow overlies a solid crust and recent wind-loading may have occurred.

Avoid travelling in areas that have been reverse loaded by winds.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Be alert to conditions that change with elevation.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

Intense spring sun and rising temperatures could reactivate buried persistent weaknesses in the upper snowpack.

Choose well supported terrain without convexities.>Use conservative route selection, stick to moderate angled terrain with low consequence.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Cornices

Tread cautiously near large overhanging cornices. Weak cornices could pop off naturally, potentially triggering large slabs on the underlying slope.

Do not travel on slopes that are exposed to cornices overhead.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 5

Valid until: Mar 29th, 2016 2:00PM