Avalanche Forecast

Issued: Mar 23rd, 2015 4:00PM

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

tim haggarty, Parks Canada

Waterton Lakes.

Cooler temperatures will allow for up to 20cm of snow this week but watch for warming on Thursday to bring an increase in the avalanche hazard.

Summary

Weather Forecast

Freezing levels should remain below 1900m with snow and then light snow to bring up to 20 cm by late Wednesday while west winds continue with moderate and even strong gusts . Thursday will bring a significant change with freezing levels rising to over 2500m as part of a warming trend that looks like it will continue into Friday

Snowpack Summary

Rain and solar heating created surface crusts below 2200m and to ridge top on solar slopes. 5 to 10 cm of new snow Saturday, as well as extensive amounts of snow available from last week, has been redistributed by strong Westerly winds to create extensive wind effect and slabs TL and ALP. The snowpack BTL is dwindling: not much remains below 1800m.

Avalanche Summary

It has been a fairly active week with high freezing levels driving a prolonged cycle. Storm and winds slabs that developed from last week's storms failed TL and above to size 2.5 mainly as a result continued wind loading. Extensive loose moist activity to sz 2 associated with rain or solar heating has affected many slopes mainly TL and below.

Confidence

Freezing levels are uncertain on Thursday

Problems

Wind Slabs

Although thin in many areas, there are some significant slabs that have grown along the ridge crests. While warm temps limited growth at TL, be prepared for larger slabs above. New snow and continued west winds will continue to build these slabs.

Use caution in lee areas in the alpine and treeline. Recent storm snow has formed touchy slabs.The recent snow may now be hiding windslabs that were easily visible before the snow fell.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Loose Wet

Heating on Thursday will likely provide quite a jolt to accumulating new now. Expect moist activity in the surface snow.

Travel early before the heat of the day, and avoid big slopes in the afternoon.Cornices become weak with daytime heating.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Deep Persistent Slabs

These layers from early season are still a concern on N aspects in the alpine, especially in shallow snowpack areas.

Avoid shallow snowpack areas where triggering is more likely.Be aware of thin areas that may propogate to deeper instabilites.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Mar 26th, 2015 4:00PM