Avalanche Forecast

Issued: Mar 18th, 2013 3:00PM

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 Persistent Slabs.

jeremy.mackenzie, Alberta Parks

Kananaskis.

Periods of intense solar radiation are possible on Tuesday, so watch for the associated rise in avalanche danger on solar aspects. The upper snowpack is complex with several crusts. Carefully evaluate the snowpack before committing to a line.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Tuesday should bring some sunny weather, but not particularly warm temperatures. Winds are expected to be moderate from the W to NW. Another wave of warm, windy and wet weather is expected late Wednesday.

Avalanche Summary

A more isolated natural avalanche cycle continued today. Both slab and loose avalanches were observed up to size 2.0, and seemed to be confined to the storm snow.

Snowpack Summary

Between 10 and 20cm of new snow fell in the past 24hrs depending on location. Storm snow totals are now near 50cm at treeline. Reverse wind loading yesterday and "traditional" wind loading today have formed touchy storm slabs on all aspects at alpine and treeline elevations. Wind transport at ridgetop was intense at times today and some sluffing was observed in steep alpine terrain. Two separate crusts crusts buried between 50 and 100cm in the snowpack are still causing concern for a step-down avalanche.

Problems

Storm Slabs

Storm slab formation continued today in alpine and open treeline terrain. Slabs up to 40cm thick are found on all aspects due to variable winds. In some cases the slabs sit on a crust layer. These slabs are currently sensitive to human triggering.

Be cautious as you transition into wind affected terrain.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 5

Persistent Slabs

A buried rain crust is found on all aspects up to 22-2400m. The bond with this new snow and the underlying crust is variable. Be sure to dig down and inspect this layer as you travel. Convex slopes at treeline and gullies are suspect.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Be very cautious with gully features.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

Up to 80cm of recent snow is overlying the Mar 3 temperature crust that is being found on solar aspects well up into the alpine. Field tests are showing the bond of the new snow to this crust as good but warm temperatures may wake up this layer.

Avoid steep Southerly aspects.>Avoid unsupported slopes.>Be aware of thin areas that may propagate to deeper instabilites.>

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 4

Valid until: Mar 19th, 2013 2:00PM