Avalanche Forecast

Issued: Mar 17th, 2014 5:13PM

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

jon stuart-smith, Parks Canada

Waterton Lakes.

New snow on top of crusts and rain soaked snow are adding to an already complex snowpack. The hazard will be higher on South facing slopes if there is significant solar radiation Tue. Hazard will also increase Wed depending on snowfall amounts.

Summary

Weather Forecast

After receiving 30-40cm over the last 48hr the snowfall will taper off tonight. Tue will be a bit of a lull but then the next system arrives on Wed with possibly another 25cm by Fri. Temperatures will be cooler, with daytime highs in the -5 to 10 ranger. Winds will return to the Waterton 'normal' of strong westerlies for the forecast period.

Snowpack Summary

Sundays rain left moist snow and crust that are now 30-40 under the surface. Below 1900 there is a complex of crusts and moist snow 40-45cm thick. Above 1900m the crusts are more discrete, with dry snow in between. The Feb facet layer is still persistent, down 70-180cm and could still be reactive in places that have not already gone.

Avalanche Summary

Not much avalanche activity has been seen Sun/Mon because of poor visibility. A long audible avalanche was heard off the back of Cameron Lake on Mon. This was likely the storm snow running on the Mar 14 melt freeze crust.

Confidence

Intensity of incoming weather systems is uncertain on Wednesday

Problems

Storm Slabs

The 30-40cm of snow from the last few days is sitting on crusts or moist snow that could provide a poor bond. Daytime heating could trigger these instabilities on south facing aspects but they may persist on cooler north aspects for a few days.

Be cautious of sluffing in steep terrain.The new snow will requires several days to settle and stabilize.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Wind Slabs

Previous windslabs are lurking just under the surface and now there is a lot of snow available for transport to start building new ones.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Avoid avalanche terrain during periods of heavy loading from new snow and wind.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

The chance of triggering the deep weak layers from early February are diminishing but these layers have not completely disappeared. Any slope that have not slid should be suspect for possible large destructive avalanches.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely

Expected Size

1 - 3

Valid until: Mar 20th, 2014 4:00PM