Avalanche Forecast

Issued: Feb 12th, 2015 5:09PM

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

tim haggarty, Parks Canada

Waterton Lakes.

A few cm over the week and warm temperatures have improved travel conditions however the avalanche hazard will not drop until the temperatures do.

Summary

Weather Forecast

After a week freeze tonight, warm conditions with a freezing level around 2000m will persist through Saturday. Sun on Friday could weaken snow on solar slopes.Â 10mm of precip expected midday Saturday. We look forward to the first good freeze in a while on Saturday night followed by mainly dry weather into the start of the week.

Snowpack Summary

Above 2000m 5 to 10cm and thin windslabs cap the 50 to 80 cm slab above the Jan 31 crust. Rain has created surface crusts below 2000m and the entire snowpack remains moist with warm temps allowing poor recovery below 1900m. 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

Cornice fall triggered thin windslabs that were enough of a load to pull a 100m wide slab out of the hanging face above Wall lake sometime in the last 36 hrs. This slab was 60 to 100cm deep and likely ran on the Jan 31 interface.

Confidence

Freezing levels are uncertain

Problems

Wind Slabs

At treeline and above expect to find superficial slabs formed by SW winds this week.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.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 - 2

Loose Wet

Below 2000m surface crusts are all that there is to hold the lid on a wet snowpack. Without a solid freeze these crusts remain weak and will break down quickly with further heating. Loose wet activity may also trigger wet slabs in isolated locations.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

These slabs that formed last weekend are sitting on a firm surface or crust 50 to 80cm deep. With continued warm conditions these slabs remain possible to trigger in many areas. The deep persistent layers could also be triggered in isolated areas.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Feb 15th, 2015 4:00PM