Avalanche Forecast

Issued: Mar 11th, 2015 8:31AM

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

pgoddard, Avalanche Canada

South Rockies.

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Summary

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

Light drizzle is possible on Thursday. Then it is expected to be dry and warm until late Saturday, when light precipitation should begin again. The freezing level is around 2200 m, climbing to 3000 m on Friday. Winds are moderate to strong from the SW.

Avalanche Summary

On Tuesday, our field team members in the north Elk Valley experienced several whumpfs on south facing treed terrain at 2200 m. They also experienced a whumpf of a hard slab near ridge top at 2450 m and saw a deep slab release on a sunny aspect that probably occurred some time in the last week. Recent loose wet avalanches up to size 1.5 appeared to have been triggered by solar warming. On Sunday, a skier-triggered slab released on a weak layer near the ground in Kananaskis Country. As temperatures remain very warm for the next few days, it might be time to change your thinking and treat the snowpack with more caution than recent conditions have warranted.

Snowpack Summary

If any snow arrives on Thursday, it may be shifted by SW winds at high elevations. Lower down the mountain, drizzle may weaken the snow surface layers, adding warmth and weight to the snowpack. Previous snow surfaces are variable and include moist snow, crusts and a little dry snow on high north aspects. The most prominent snowpack feature is a thick supportive crust 10-30cm below the surface. It extends up to around 2200m elevation. This crust has begun to break down in response to warm temperatures, and may not be providing the “capping” support it once was. Persistent weak layers still react in snowpack tests and could wake up with continued warming. It may be time for a mentality shift.

Problems

Wind Slabs

Hard wind slabs may be triggered by the weight of a person near ridge tops.

Use ridges or ribs to avoid pockets of wind loaded snow.>Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Deep Persistent Slabs

We have concerns about this problem "waking up" with warm temperatures. A crust that previously isolated deep weaknesses has broken down with warming. Recent whumpfing indicates unstable snow.

Be aware of thin areas and rock outcroppings where you are more likely to trigger a deep slab.>Avoid large slopes during times of warm temperatures.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Loose Wet

Both loose wet avalanches and cornice falls are a concern while the weather remains warm.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Cornices become weak with heating, so avoid exposing yourself to them.>Avoid steep or committing slopes if the snow is moist or wet.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Mar 12th, 2015 2:00PM