Archived

Avalanche Forecast

Feb 9th, 2015–Feb 12th, 2015

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Waterton Lakes.

New slabs formed at upper elevations are substantial and will take some time to settle over the previous crusts. Weak surface crusts breaking down with daytime heating make for difficult travel below treeline.

Weather Forecast

A weak ridge will form over the region by midday on Tuesday to bring some drier air and hopefully allow some cooling through Wednesday with only trace amounts of precip forecast. Thursday marks the beginning of an increasing trend in the freezing level through to the weekend. Winds will remain light to moderate out of the SW for the period.

Snowpack Summary

50cm of snow fell with strong SW winds on the Jan 31 crusts above 2000m with the last storm. Rain has created surface crusts below 2200m and the entire snowpack remains moist with warm temps allowing only poor recovery. The Dec 13 layer down about 1m average is still a concern in high shaded terrain where there are no strong crusts above it.

Avalanche Summary

There was a great deal of avalanche activity over the weekend. With the rapid loading and winds, storms slabs to sz 2.5 failed above the Jan 31 crusts treeline and above some as a result of cornice failures. Below treeline surface crusts broke down with the rain allowing loose wet activity and a few wet slabs failing on the Dec 13 crust layer,

Confidence

Avalanche Problems

Storm Slabs

At upper elevations the new snow combined with mild temperatures and strong SW winds has created 50cm soft slabs. Rain crusts overly these new slabs to 2200m. Be cautious with steep or unsupported terrain until these slabs can settle and cool.

Be cautious as you transition into wind affected terrain.The new snow will require several days to settle and stabilize.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3

Loose Wet

Below 2000m the snowpack has been hit mainly by rain. Surface crusts are just beginning to form and are all that there is to hold the lid on what remains of the soaked snowpack.

Avoid unsupported slopes.Travel early on frozen crusts before the heat of the day.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Deep Persistent Slabs

Now 40 to 120cm deep these slabs continue to stand out as a real concern in the TL and ALP areas that do not have strong surface crusts. Be particularly mindful in thin snowpack areas where this layer is more likely to be triggered.

If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Dig down to find and test weak layers before committing to a line.

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

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3