Archived

Avalanche Forecast

Feb 13th, 2015–Feb 14th, 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

3: Considerable

The avalanche danger rating below treeline will be considerable

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

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Kananaskis.

A Special Public Avalanche Warning (SPAW) has been issued for the region. The concern is the unusually slow bonding within the entire snowpack. Recent slab avalanches have been large and in many cases very surprising.

Confidence

Good

Weather Forecast

Saturday will be very similar to today. The temps today exceeded the forecasted values, so we can expect something similar tomorrow. Sunny periods are expected, solar heating could be an issue on south aspects. The forecasted freezing level is 2000 with a 2500m high of -2. The 2500m winds should be steady at 40km/hr from the NW. No snow (or rain) is expected.

Avalanche Summary

A bombing mission on Rundle had limited results. 3 of the 4 bombs produced avalanches up to sz2. All of them failed on the Jan31st layer. Previous control had dealt with the deeper layers, so these results are not necessarily transferable to the backcountry.

Snowpack Summary

Today's temperatures reached well above zero in all forecast areas. The Aster Lake region hit +3 degrees. The lack of an overnight freeze left the valley bottom snow isothermal in places. This condition gradually improves with elevation, but generally the snow up to treeline has had significant warming. Treeline and above has windslabs that are dense, and relatively warm. Whumphing is less common now, but the weak interface is still present. The Jan31st interface is still the main concern at all elevations. At treeline it is down 50-60.

Avalanche Problems

Wind Slabs

At treeline these slabs have gone through some warming/cooling trends. Despite this, the bond with the Jan31 layer is still considered to be weak and suspect. Treat steep terrain at treeline and alpine elevations with caution.

Choose well supported terrain without convexities.>Dig down to find and test weak layers before committing to a line.>Resist venturing out into complex terrain, even if you observe no obvious signs of unstable snow.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Deep Persistent Slabs

In big terrain this is a serious concern. Variable depth snowpacks and terrain with large, potential triggers should be avoided. Avoid exposure to avalanche runout zones.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.>Be wary of slopes that did not previously avalanche>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 3 - 6

Cornices

With the warmth, comes the risk of cornices collapsing. Most cornices have had extended exposure to the sun and warm air. They are ripe, and ready to be a trigger for deeper layers.

Avoid steep slopes below cornices.>Cornices become weak with daytime heating. >

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 3