Avalanche Forecast

Issued: Dec 9th, 2017 4:18PM

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

conrad janzen, Parks Canada

Banff Yoho Kootenay.

Travel is easy, and while the ski quality has suffered from the recent winds, it is a great time for an alpine tour. There are still places where you could trigger an avalanche on the buried facets so use caution when entering steep alpine terrain.

Summary

Weather Forecast

The high pressure system remains entrenched over the Rocky Mountains with no snow for the next week. The temperature inversion remains and strengthens through the beginning of next week with very high freezing levels forecasted for Monday and Tuesday. Winds remain in the moderate range out of the West for the next few days.

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. 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

In the last 24 hours 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

Freezing levels are uncertain on Monday

Problems

Persistent Slabs

Some uncertainty around the possibility for triggering the Halloween layer remains but we are not seeing any avalanches at this point. The most likely trouble spots would be steep alpine areas where a hard surface slab sits over the weaker facets.

Be aware of thin areas that may propogate to deeper instabilites.Assess start zones carefully and use safe travel techniques.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Dec 10th, 2017 4:00PM