Archived

Avalanche Forecast

Feb 24th, 2018–Feb 25th, 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

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: Lizard-Flathead.

New wind slabs are building quickly. These can be triggered by the weight of a person.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

SUNDAY: 15 cm light dry snow. Freezing level near 1000 m. Light to moderate south-westerly winds.MONDAY: Mainly cloudy with flurries possible. Freezing level near 700 m. Moderate west to north-westerly winds. TUESDAY: 5-10 cm snow. Freezing level near 1000 m. Moderate to strong south-westerly winds.More details can be found in the Mountain Weather Forecast.

Avalanche Summary

A skier triggered a size 2 slab on a steep south-east facing slope near ridge crest at 1970 m on Saturday. It was 20-60 cm deep and failed on facets. Explosives testing produced several loose dry avalanches in steep terrain. A natural cornice fall triggered a size 2 wind slab on a north-east aspect.A skier also remotely triggered a size 2 persistent slab on a north aspect at 1750 m. It failed on surface hoar, which is isolated in its distribution, but is most likely found on sheltered north aspects.A developing wind slab problem was observed as winds picked up throughout the day. These problems are expected to continue to develop, and may be especially touchy in specific locations where they overlie buried persistent weak layers.

Snowpack Summary

New wind slabs are building quickly as available light dry snow is moved around by moderate winds. Snow spillage from steep ground is also loading up fan features. In more sheltered locations, you may encounter storm slabs or loose dry sluffing. These upper snowpack problems overlie various old surfaces including old hard wind slabs, crusts, facets and spotty surface hoar. Storm slabs and wind slabs were becoming reactive to human triggers on Saturday in some areas.Deeper in the snowpack, the widespread mid-December weak layer sits about 130-220 cm deep. This consists of a crust, facets or surface hoar. Near the base of the snowpack, a crust/facet layer could be awoken from a thin-spot trigger point, or with a very large load like a cornice fall.

Avalanche Problems

Wind Slabs

Wind slabs are touchy and can be triggered by you. They can be found near ridges and ribs.

Travel on ridgetops to avoid wind slabs on slopes below.Minimize exposure to overhead hazard from cornices.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2

Storm Slabs

Storm snow will be especially sensitive to human triggers in steep or convex terrain.

Avoid travelling on ledges and cliffs where sluffing may have severe consequences.Avoid open slopes and convex rolls at treeline where buried surface hoar may be preserved.Choose conservative lines and watch for clues of instability.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2.5