Avalanche Forecast

Issued: Feb 16th, 2015 4:00PM

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

tim haggarty, Parks Canada

Waterton Lakes.

Fast travel and good weather make for some of the best conditions in weeks. The snowpack has gained a lot of strength but problems continue to linger in the high and shaded terrain where deep layers are not protected by thick crusts.

Summary

Weather Forecast

After a cold start to the day on Monday clearing skies and light winds will allow modest heating under a gradual warming trend. By Wednesday freezing levels could reach the alpine especially combined with clear skies however winds may start to increase as well. More cloud is expected by Thursday. Solar heating seems like the variable to watch.

Snowpack Summary

10cm of snow that fell over the weekend sits on rain and temperature crusts to 2000m and thin solar crusts to mountain top. Below this old windslabs cap the 50 to 80 cm slab that seems well bonded to the Jan 31 crust. The Mid-December 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 significant solar and heat induced loose moist activity while conditions remained warm last week. Things have cooled over the weekend and the snowpack has begun to refreeze creating strong surface crusts below tree line. Avalanche activity has diminished as a result with no new avalanches seen since Saturday.

Confidence

Freezing levels are uncertain on Wednesday

Problems

Wind Slabs

Although these old slabs have seen a lot of abuse from warm temperatures they do produce the only shears in the upper snowpack. Keep an eye on these if you are considering taking on serious terrain.

Use caution in lee areas. Recent wind loading have created wind slabs.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Deep Persistent Slabs

Now 40 to 120cm deep these slabs continue to stand out as a concern in the TL and ALP areas where there is not a strong Jan 31 crust over them (2200m+). Be particularly mindful in thin snowpack areas where this layer is more likely to be triggered.

Carefully evaluate big terrain features by digging and testing on adjacent, safe slopes.Avoid convexities or areas with a thin or variable snowpack.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Cornices

Given the amount of sun in the forecast and that cornices exist above some of the more sensitive snowpack areas out there right now, keep your mind tuned to your exposure. These big triggers may get the deep persistent slabs moving.

Pay attention to overhead hazards like cornices.Cornices become weak with daytime heating.

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Feb 19th, 2015 4:00PM