Avalanche Forecast

Issued: Mar 14th, 2014 5:51PM

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

jon stuart-smith, Parks Canada

Waterton Lakes.

Conditions continue to be tricky because of warm temperatures, rain/snowfall. There continues to be concern for the persistent week layer and it's potential to propagate. Crusts exist on all aspects up to ridgetop making for challenging travel.

Summary

Weather Forecast

Saturday will be cooler with isolated flurries but sunny periods because another storm system arrives on Sunday morning. This storm could bring another 40cm of snow with strong SW winds adding to already building windslabs on lees slope. Freezing levels will climb up to around 1700m again meaning rain or wet snow is likely below this elevation.

Snowpack Summary

Suncrusts have formed on solar aspects. These are buried by 10cm of snow that fell today above 1700m, below that was wet snow/rain. Moist snow is still present under the crusts to 1900m from rain on 0310. Feb facet layer down 70-170cm and large avalanches have resulted when this layer is triggered because of the propagation potential of this layer.

Avalanche Summary

Although natural activity has tapered off, helicopter bombing of the path that hit the Akamina parkway on the weekend produced numerous sz 1.5 as well as a 2.5 that almost hit the road again. The active layer is still the Feb facet layer. Small loose dry avalanches occurred today at higher elevations while loose wet avlanaches occurred below 1700m.

Confidence

Intensity of incoming weather systems is uncertain on Sunday

Problems

Wind Slabs

New snow Fri is starting to build windslabs on lee slopes. The storm snow forecast for Sun/Mon will build these deeper. These will need some time to settle.

Use caution in lee areas. Recent wind loading have created wind slabs.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

1 - 2

Loose Wet

With freezing levels climbing during the daytime, precipitation at lower elevations will be wet snow or rain. Loose wet avalanches will be likely depending on the amount of snow and if rainfull is heavy wet slab avalanche will also be a concern.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Persistent Slabs

The layer down 70-170 cm is still active as demonstrated Thur with avalanche control work up Akamina. Any slope not yet slid should be a concern. Windslabs, cornices, storm slabs or wet loose avalanches could step down and result in large avalanches.

Minimize overhead exposure during periods of heavy loading from new snow, wind.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely

Expected Size

1 - 3

Valid until: Mar 17th, 2014 4:00PM