Avalanche Forecast

Issued: Mar 21st, 2013 5:06PM

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

tim haggarty, Parks Canada

Waterton Lakes.

Great skiing at higher elevations with 20cm of new snow, but still fair at lower elevations with new snow starting to cover the recent crust. Watch for solar heating to raise the hazard on sunny slopes Saturday and especially Sunday.

Summary

Weather Forecast

Friday, Saturday: overcast with light flurries, light winds, highs of -5 at tree line, 5-10 cm total. Sunday increasing winds out of the North, clear skies with the temperatures increasing to -3 at tree line. The increased solar radiation on Sunday will have a strong effect on the surface layers and affect stability on the snow above the crusts.

Snowpack Summary

20cm new snow overlies the March 21 rain crust that can be felt as high as 1900m and a sun crust that goes to ridge top on S aspects. This HN tapers with elevation covering moist snow and a weak crust below 1600m. There is 40 to 60 cm over the March 15 rain crust that is present to 2400m. Thin wind slabs forming at ridge crests N to SE aspects

Avalanche Summary

There has been a fair amount of loose dry activity out of extreme terrain after last week's major storm but surprisingly little slab activity. Yesterday rain as high as 1900m generated minor loose moist activity at lower elevations. New wind slabs are now forming as winds from the West have increased.

Confidence

Timing or intensity of solar radiation is uncertain

Problems

Wind Slabs

Moderate West winds are building windslabs on N & E aspects near ridge crests in open areas treeline and above. These slabs are currently thin and spotty near treeline but will be more developed above. We would expect these to settle quickly and bond

Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Loose Wet

With the clear skies forecast on Sunday expect activity on solar aspects as things heat up. Most of this will likely be black body starts or minor surface sluffing but if the moisture penetrates to the well developed crusts this could produce more.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Mar 24th, 2013 4:00PM