Avalanche Forecast

Issued: Feb 11th, 2019 4:03PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs.

Avalanche Canada dsaly, Avalanche Canada

A dusting of new snow and wind will hide older, recently formed wind slabs and build new slabs over old ones. The largest accumulations of snow, and potentially the most reactive, will be found in wind-loaded terrain.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Tuesday

Weather Forecast

MONDAY NIGHT: Cloudy with clear periods and isolated flurries, trace to 10 cm accumulation with the larger snowfall amounts forecasted for the southern part of the forecast region. Alpine temperatures near -20C. Ridgetop winds light to moderate from the northeast.TUESDAY: Cloudy with isolated flurries, up to 10 cm accumulation . Alpine temperature near -15C. Ridgetop winds light from the east-northeast.WEDNESDAY: Mix of sun and cloud. Alpine temperatures near -10C. Ridgetop winds light from the west-southwest.THURSDAY: Cloudy with sunny periods and isolated flurries, up to 10 cm accumulation. Alpine temperatures near -10C. Ridgetop winds light gusting moderate from the south.

Avalanche Summary

Two separate weekend reports from the Duffy/Joffre Lakes area document stiff wind slabs easily triggered by skiers including two size 2 skier triggered wind slab avalanches. In both cases, the avalanche occurred in steep and wind-loaded feature on a northerly alpine feature (see the Tszil MIN report here).

Snowpack Summary

A light dusting of snow fell on variable wind-pressed, wind-sculpted, exposed crust and windslab surfaces covering alpine and higher treeline elevations. The recent extreme wind event deposited snow lower in start zones than usual and developed wind slabs in more protected areas and at lower elevations.Due to scouring and wind-loading, anywhere from 0-60 cm of this wind-affected snow sits on a crust on all aspects below 2000m and solar aspects into the alpine. Current cold temperatures are promoting surface faceting and are breaking down the buried crust at high elevations. In isolated and sheltered terrain at treeline and below, a layer of weak feathery surface hoar or sugary facets may be identified, but with little reactivity. Below the recent wind affected snow and crust, another crust is found down 50-80 cm that formed mid-January right to mountain top on southerly aspects and on all aspects below 1700 m. Additionally at this depth, feathery surface hoar may be found in shady sheltered areas at treeline, but with little reactivity.The remainder of the snowpack is generally well-settled.

Problems

Wind Slabs

An icon showing Wind Slabs
Recent widespread wind effect through the region developed reactive wind slabs in steeper features and wind-loaded terrain. With 10 cm falling Tuesday with moderate winds, expect new slab development and older wind slabs hidden under new snow.
Watch for whumpfing, hollow sounds, and shooting cracks.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Feb 12th, 2019 2:00PM

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