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Archived

Avalanche Forecast

Mar 11th, 2018–Mar 12th, 2018
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
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
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.

Freezing levels above the mountain tops and sunny skies are warming the snowpack, particularly around midday. Best to avoid sunny slopes and overhead avalanche terrain. Read our blog on the impact of warming.

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

MONDAY: Sunny, light southwesterly winds, alpine temperature 1 C, freezing level rising to 2500 m.TUESDAY: Sunny, light southwesterly winds, alpine temperature 3 C, freezing level 3000 m.WEDNESDAY: Mostly sunny, light southwesterly winds, alpine temperature 3 C, freezing level 2500 m.

Avalanche Summary

Numerous small loose avalanches were noted on solar aspects on Saturday with strong solar input.  The forecast warming and sunshine may wake up a deeper weak layer on steep south facing slopes resulting in large and destructive avalanches.

Snowpack Summary

20 cm of recent storm snow is settling rapidly with warm daytime temperatures.  Expect moist snow on solar aspects and on all aspects up to 1400 m.Cornices are large and prone to failure with warm air temperatures and sunny skies.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 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. This is most likely to occur on south-facing slopes.

Avalanche Problems

Deep Persistent Slabs

Deeply buried weak layers linger near the base of the snowpack. These layers are most likely to be triggered from thin snowpack areas or with a large load like a cornice fall.  Avoid overhead avalanche paths and looming cornices.
Steep, south facing slopes are the most likely areas to trigger deeper layers.Avoid steep, rocky, and shallow snowpack areas where triggering deeper layers is more likely.Pay attention to overhead hazards like cornices which could trigger deep persistent slabs.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 3.5

Loose Wet

Rising freezing levels and sunny skies are causing intense warming of the snowpack on solar aspects.  Pay close attention to the effects of the sun on avalanche terrain and avoid overhead exposure.
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

Expected Size: 1 - 2