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Avalanche Forecast

Mar 27th, 2016–Mar 28th, 2016
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
2: Moderate
The avalanche danger rating below treeline will be moderate
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
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

Regions: South Columbia.

Warming and sunshine will drive avalanche danger this week. Plan to start your day early and to avoid large sun-drenched slopes during the heat of the day.

Confidence

High

Weather Forecast

MONDAY: Cloudy with a chance of flurries and sunny breaks in the afternoon. The freezing level climbs to 1600-1800 m and winds are moderate from the N-NE. TUESDAY: Mainly sunny. The freezing level is around 2000 m and winds remain light to moderate from the N-NE. WEDNESDAY: Mainly sunny. The freezing level spikes to 2300-2600 m and winds are light from the NE.

Avalanche Summary

On Saturday there was a report of a natural cornice fall that triggered a size 3 persistent slab on a steep, rocky, north-facing slope. There was also some minor loose wet sluffing to size 1.5 on steep sun-exposed slopes in the afternoon. On Friday, just outside the northern extent of the region, there was a report of a very large (size 4) persistent slab on a large south-facing slope that was triggered by new snow loading. This avalanche likely failed on the late February interface.

Snowpack Summary

Light new snow covers a variety of old surfaces including crusts on solar aspects, moist snow up to treeline, and dry snow or fresh wind slabs in the alpine on shaded aspects. Approximately 40-50 cm of settled storm snow sits on a melt-freeze crust buried on Mar. 22. The late February persistent weak layer is an aspect dependant mix of surface hoar, facets and/or a thick crust down around 60-110 cm below the snow surface. Commercial operators continue to see hard sudden planar results in snowpack tests, which suggests that wide fracture propagations are possible. Cornices continue to be described as large and fragile. Expect loose wet avalanches and natural cornice falls during periods of strong solar radiation and/or daytime warming.

Avalanche Problems

Storm Slabs

Forecast strong northerly winds could create new wind slabs on solar aspects, which could become very touchy if the sun makes an afternoon appearance.
Be alert to conditions that change with elevation.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Avoid travelling in areas that have been reverse loaded by winds.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 3

Persistent Slabs

A buried persistent weakness, around 60-100 cm deep, could reactivate with strong spring sunshine and climbing temperatures this week.
Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Use conservative route selection, stick to moderate angled terrain with low consequence.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely

Expected Size: 3 - 6

Cornices

Cornices are large and weak and could fail easily during periods of sun and from daytime warming.
Do not travel on slopes that are exposed to cornices overhead.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 5