Archived

Avalanche Forecast

Mar 18th, 2015–Mar 19th, 2015

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

2: Moderate

The avalanche danger rating below treeline will be moderate

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

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

Regions: Glacier.

Human triggered avalanches continue to occur. Be diligent in your terrain selection and pay attention to the clues of instability. Whumphing is a good indication that weak layers are reactive in your area.

Weather Forecast

Today expect mostly sunny skies. Gusty winds will keep alpine temps cool, but sun and above freezing temps below treeline may weaken the surface. By tomorrow expect cloudy skies with flurries starting in the afternoon. Freezing levels will be ~1800m, with up to 10cm of new snow and moderate SW winds. By Friday freezing levels will rise to 2100m.

Snowpack Summary

At treeline and above, pockets of wind slab formed by strong to extreme winds from last Saturday night overlie a combination of crusts, faceted snow and old windslabs. The Feb19th surface hoar down 30-45cm has variable distribution. Below 1800m a melt freeze cycle, following recent rain, is starting to form a supportive melt freeze crust.

Avalanche Summary

Yesterday skiers triggered a slab avalanche on Youngs Peak. It was on a NW aspect, ~2400m, was reported to be 15-60cm deep, 30m wide and 100m long. In the region, windslabs have been triggered by riders daily causing avalanches to size 2. Whumphing continues to be reported from treeline areas throughout the park.

Confidence

Timing, track, or intensity of incoming weather system is uncertain

Avalanche Problems

Wind Slabs

Touchy windslabs continue to be reactive to human triggering. They are most likely to be triggered from a convexity and may propagate widely. Recent winds have also added to cornices, which are fragile and if they fail provide a large trigger.

Watch for whumpfing, hollow sounds, and shooting cracks.Choose well supported terrain without convexities.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Persistent Slabs

The upper snowpack is complex, with a multitude of crusts, weak facetted layers, and surface hoar. Solar radiation weakens surface crusts and may make these layers in the top 60cm more reactive. Large slab avalanches have occurred on these layers.

Be aware of the potential for large, deep avalanches.Be aware of the potential for wide propagations.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 3

Loose Wet

Watch for moist snow and loose avalanches originating from cliffs as indications of instability. At lower elevations you can probe with your pole to see how thick the crust is and determine whether it is breaking down with day time warming.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2