Archived

Avalanche Forecast

Mar 21st, 2017–Mar 22nd, 2017

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

Regions: South Rockies.

Forecast snowfall and freezing levels are uncertain, but expect a pulse of weather on Tuesday night to drive up the danger on Wednesday.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

TUESDAY NIGHT: A short pulse of warm wet weather overnight will bring 5-10 mm of precipitation, strong southwest wind, and freezing level up to 2000 m.WENDESDAY: Cloudy with isolated flurries, strong southwest wind, freezing level dropping to around 1800 m.THURSDAY: Mix of sun and cloud, moderate southwest wind, freezing level around 1700 m with alpine temperature around -4 C.FRIDAY: Increasing cloud, moderate southwest wind, alpine temperature around -1 C.

Avalanche Summary

No recent avalanches have been reported. Evidence of a large natural avalanche cycle during last week's storm has been reported around the Crowsnest Pass / Sparwood area (typically size 2.5 deep persistent slabs). A fresher size 3 avalanche in the Alexander Creek drainage was possibly triggered by a cornice fall on Sunday. Widespread natural activity in the neighboring Kananaskis region suggest conditions may be touchier north of Elkford.New snow should form wind slabs at higher elevations, well warming and cornice falls are potential triggers for deep persistent slab avalanches.

Snowpack Summary

Light amounts of alpine snow will form wind slabs in the alpine on Tuesday night. Meanwhile at lower elevations, light rain will soak the snowpack once again. Recent rain and sun have left a variety of crusts that are thicker and most supportive in open south facing terrain. Below the new snow and crusts, roughly 50-90 cm of snow sits above the February crust and facet interfaces. In some areas there may still be a poor bond to these interfaces. The bottom third of the snowpack is composed of weak facets and full-depth avalanches over this basal weakness remain a concern.

Avalanche Problems

Wind Slabs

Incoming snow and wind will likely form fresh wind slabs in the lee of exposed terrain.

Use ridges or ribs to avoid pockets of wind loaded snow.If triggered, wind slabs may step down to deeper layers and result in large avalanches.Be alert to conditions that change with elevation and aspect.

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

Elevations: Alpine.

Likelihood: Likely

Expected Size: 1 - 2

Deep Persistent Slabs

Warming and cornice falls are potential triggers for large avalanches on deep weak layers. Be aware of this as a potential overhead hazard when traveling at lower elevations.

Avoid exposure to overhead hazards during periods of rain.Wind slabs or cornice releases may trigger deep layers and result in large avalanches.Recognize and avoid avalanche runout zones.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 4