Archived

Avalanche Forecast

Mar 9th, 2018–Mar 10th, 2018

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

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

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Regions: South Rockies.

Sunshine and warming will increase hazard throughout the weekend. Natural loose wet avalanches are expected on steep south facing slopes and lingering wind slabs reactive to human triggers below ridgetops.

Confidence

High -

Weather Forecast

SATURDAY: Sunny / Light southwesterly ridgetop winds / Freezing level rising to around 1700 m.SUNDAY: Sunny / Light southwesterly ridgetop winds / Freezing level rising to around 2000 m.MONDAY: Sunny / Light southwesterly ridgetop winds / Freezing level rising to around 2400 m.

Avalanche Summary

No new avalanches were reported in this region on Thursday. Explosive control work northwest of Elkford on Tuesday produced numerous size 3 persistent slab avalanches failing on facets near the base of the snowpack. The most notable results were on steep, rocky north aspects, and lower angled west aspects.

Snowpack Summary

Up to 20 cm of new snow overlies sun crusts on solar aspects. Cornices are large and prone to failure over the weekend due to forecast sunny skies and rising freezing levels.The upper/mid-pack is generally well settled and strong.The lower snowpack is weak with a combination of crusts and facets near the bottom of the snowpack that are widespread. The primary concern looking ahead towards the weekend and early next week is the potential of these deeper persistent weak layers becoming active by rapid warming of the snowpack through rising freezing levels and intense solar radiation.

Avalanche Problems

Wind Slabs

Freshly formed wind slabs reactive to human triggers are expected on lee features below ridgetops

Use ridges or ribs to avoid pockets of wind loaded snow.Watch for newly formed wind slabs as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Loose Wet

Forecast sunshine is expected to trigger loose wet avalanches on steep south facing slopes.

Avoid terrain traps such as gullies and cliffs where small avalanches can have high consequence.Watch for signs that the snow is heating up such as pin-wheeling and point-releases below cliffs.Start early to staff off south facing slopes during the heat of the day.

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

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 2

Deep Persistent Slabs

Deeply buried weak layers are lingering near the base of the snowpack. These layers are most likely to be triggered from thin or variable snowpack areas or with a large load like a cornice fall.

Extra caution needed around cornices with current conditions.Avoid steep convexities or areas with a thin or variable snowpack

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely

Expected Size: 2 - 3.5