Avalanche Forecast

Issued: Dec 10th, 2017 4:00PM

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

Parks Canada tim haggarty, Parks Canada

Email

Banff Yoho Kootenay.

While the alpine snowpack structure does not inspire too much confidence, we have been through a good test. With long periods of above freezing temperatures near mountain top and many people out exploring, no avalanche activity has been reported.

Summary

Weather Forecast

The high pressure system remains entrenched over the Rockies until at least Friday. The temperature inversion will rebuild Monday with mountain-top freezing levels through midday Tuesday.  Moderate winds can be expected at upper elevations and lower in areas that funnel West winds.

Snowpack Summary

Extensive wind effect at treeline and above. Sun crusts are present on some steep south facing slopes. Surface hoar up to 25mm has formed below 2200m and surface faceting is in progress. 15-40 cm of snow lies over the Nov 27th and Nov 23rd crusts. Both of these now overlie the Halloween crust/facet layer that sits 30-50cm above the ground.

Avalanche Summary

During the last few days with inverted temperatures yielding above freezing conditions treeline and above, only a few very small loose wet avalanches in the alpine were observed. These were in steep rocky terrain that was in the sun, and sheltered from the wind. Where observed, these did not triggered any deeper weaknesses.

Confidence

Due to the number of field observations

Problems

Persistent Slabs

An icon showing Persistent Slabs
Some uncertainty for triggering the Halloween layer remains but we have come through a warm period and a lot of skier testing produced no activity over the past five days.  These slabs still deserve respect in steep and shallow areas.
Assess start zones carefully and use safe travel techniques.Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely

Expected Size

1 - 2

Valid until: Dec 11th, 2017 4:00PM

Login
Join