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Archived

Avalanche Forecast

Dec 29th, 2023–Dec 30th, 2023
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
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
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Above freezing alpine temperatures mean persistent weak layers will remain a concern.

Steep, convex and shallow areas are where triggering is most likely.

Confidence

Moderate

Avalanche Summary

On Wednesday, a few large (size 2 to 3) natural and explosive triggered persistent and deep persistent slabs were reported in the alpine. A few smaller (size 1.5) natural windslab and storm slabs have also been seen.

Moving forward, natural avalanche activity has tapered, but large human-triggered slabs remain possible.

Snowpack Summary

Generally wind affected snow is present on the surface in the alpine and treeline. Below treeline a new crust is on or near the surface.

The mid pack contains several layers of note; a layer of surface hoar and a crust down 20 to 40 cm, a significant crust from the early December rain event down around 50 cm and a layer of surface hoar down 50 to 90 cm.

The make up of the lower snowpack is variable throughout the region, in shallower snowpack areas, basal facets exist. This is most concerning in shallow alpine areas.

Weather Summary

Friday night

Clear with no new snow. Southeast alpine wind 10 to 30 km/h. Freezing level up to 2400 m.

Saturday

A mix of sun and cloud, no new snow. Southeast alpine wind 10 to 30 km/h. Freezing level up to 1700 m, with the potential for an above freezing layer in the alpine up to 2400 m.

Sunday

Mainly cloudy with isolated flurries, 1 to 3 cm accumulation. Southwest alpine wind 10 to 30 km/h. Treeline temperature -2 C.

Monday

Mainly cloudy with isolated flurries, 1 to 3 cm accumulation. Southwest alpine wind 10 to 40 km/h. Treeline temperature -4 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Keep in mind that human triggering potential persists as natural avalanching tapers off.
  • Use careful route-finding and stick to moderate slope angles with low consequences.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
  • Overhead hazard may not be obvious, evaluate prior to commiting to terrain.

Avalanche Problems

Deep Persistent Slabs

A weak layer of basal facets means shallow snowpack areas are most likely trigger points. The possibility for large natural avalanches means that overhead hazard should be given due caution.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3.5

Persistent Slabs

A layer of surface hoar is down 50 to 90 cm and is still concerning in places that haven't already avalanched.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 1.5 - 3