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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
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
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
1: Low
The avalanche danger rating below treeline will be low

Regions: Northwest Inland.

Wind slabs continue to build. Back off if you encounter drummy, hollow snow, whumpfing or recent avalanche activity.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

SATURDAY NIGHT: 5-10 cm snow. Strong south-westerly winds. SUNDAY: Mainly cloudy with light snow. Freezing level near 400 m. Moderate westerly winds.MONDAY: Mainly cloudy with light snow. Freezing level near 400 m. Strong westerly winds.TUESDAY: Mainly cloudy with light snow. Freezing level near 400 m. Moderate to strong westerly winds.More details can be found in the Mountain Weather Forecast.

Avalanche Summary

Rapid wind loading caused a natural avalanche cycle to size 2.5 on Wednesday. With ongoing moderate to strong winds forecast, wind slabs will remain possible to trigger over the next few days. Persistent slabs could still be triggered from thin-to-thick snowpack areas, or with a heavy load like a cornice fall.

Snowpack Summary

Light snow and strong winds over the weekend are building wind slabs in open terrain at alpine and treeline elevations. These overlie buried old hard wind slabs, scoured surfaces and sastrugi in many exposed areas. In wind-sheltered terrain, sun crusts or dry facets sit below the recent storm snow.The wind slabs sit on various old surfaces including sun crusts, facets and spotty surface hoar (which is most prevalent in sheltered treed locations). Around 50-150 cm down, you will find a crust/surface hoar layer from mid-January, which still has the chance to surprise you and could be triggered from a thin snowpack spot, or with a large trigger like cornice fall. Facets at the base of the snowpack can possibly be triggered from shallow snowpack areas.

Avalanche Problems

Wind Slabs

Wind slabs are widespread and could be triggered by the weight of a person.
Travel on ridgetops to avoid wind slabs on slopes below.Give cornices a wide berth when travelling on or below ridges.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2.5

Persistent Slabs

Buried weak layers are most likely to be triggered from thin or variable depth snowpack areas; or with a large load like a cornice fall.
Avoid thin, rocky or sparsely-treed slopes.If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 1.5 - 3.5