Avalanche Forecast

Issued: Dec 16th, 2013 4:00PM

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

snow safety, Parks Canada

Banff Yoho Kootenay.

Expect another 15-25 cm of snow on Tuesday with very strong winds. Conditions have deteriorated over the past few days through this storm. Be patient, cold air arrives on Wed and with that the avalanche conditions will improve. GS

Summary

Weather Forecast

Another system embedded in a strong westerly flow will bring 15-25 cm of snow to areas around Lake Louise and Bow Summit on Tuesday, with less snow expected in southern areas. Winds will continue to be very strong (35-85 km/hr), with temps from -5 to -9. Clearing and cooler air arrive on Wednesday, with temps reaching -15 to -20 by Thursday.

Snowpack Summary

Areas on the west side of the Continental Divide have received up to 20 cm of snow in the last 36 hours, for a total of approximately 40 cm over the past four days. Strong to extreme winds at treeline and above have created windslabs in most open areas. Total snowpack depths range from 60-100 cm, with the lower half comprised of weak facets.

Avalanche Summary

Sunshine Village reported a ski cut size 2 avalanche that started as a 40 cm deep wind slab, then stepped down to the facets at the base of the snowpack (max fracture depth 150 cm). Similarly, Lake Louise avalanche control reported loose snow avalanches acting as a trigger for a deeper size 2 running on the weak facets near the ground.

Confidence

on Thursday

Problems

Wind Slabs

Continued snowfall and strong winds will create deep windslabs in most areas above treeline. Stay off steep, loaded slopes and climbers should avoid deep, avalanche prone gullies where spindrift is forming windslabs.

Be cautious as you transition into wind affected terrain.Minimize overhead exposure; avalanches triggered by wind loading may travel long distances.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Deep Persistent Slabs

The base of the snowpack is weak and should not be trusted this early in the season. Avoid large open slopes in alpine and treeline areas.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Dec 17th, 2013 4:00PM