Archived

Avalanche Forecast

Mar 4th, 2016–Mar 5th, 2016

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: South Rockies.

Strong winds on Saturday will continue to add new load to leeward features in exposed alpine terrain.Extra caution is required around and below large cornices during the heat of the day.

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

A weak storm pulse is expected to bring 2-4mm of precipitation on Saturday. Freezing levels are expected to be around 2000m or higher and alpine winds are forecast to be strong from the southwest. A bit of a break is expected Saturday afternoon or evening before a second storm system arrives Saturday overnight. 4-8mm of precipitation is expected by midday Sunday with freezing levels around 2300m and strong southerly winds in the alpine. Sunday afternoon and Monday are currently forecast to be dry and sunny.

Avalanche Summary

No new avalanches were observed on Thursday. On Wednesday, two natural size 1.5 storm slabs were reported from the north of the region. These were 30cm thick and released on an southeast-east aspect in the alpine. A natural size 1.5 loose dry avalanche was also reported in the north from an east aspect gully feature in the alpine. In the southeast of the region, several size 1 wind slabs were ski cut on north through east aspects at 1800-2100m elevation. These were 10-30cm thick on steep leeward features around ridge crests. Ongoing strong southwest winds are expected to continue to build wind slabs in leeward features in the alpine on Saturday. Cornices are expected to become weak with daytime warming and sun.

Snowpack Summary

15-25cm of recent storm snow with strong southwest winds have formed wind slabs in leeward features. The recent snowfall may overlie a sun crust on steep solar aspects or small surface hoar in isolated sheltered areas. The recent wind has also formed large cornices which are expected to become weak with the forecast warming and sun. Old weak layers can still be found in the snowpack but these layers are reported to be well bonded and triggering has become unlikely.

Avalanche Problems

Wind Slabs

Recently formed wind slabs are expected to be reactive to human-triggering. Ongoing winds will continue to load leeward features.

Travel on ridgetops to avoid wind slabs on slopes below.>Avoid freshly wind loaded features.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3

Cornices

Cornices are expected to be fragile and may fail naturally with daytime warming and sun exposure. Not only are they a hazard in themselves, but also a heavy trigger for slabs on the slope below.

Cornices become weak with daytime heating, so travel early on exposed slopes.>Extra caution needed around cornices with current conditions.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 3