Avalanche Forecast Sea to Sky

Monday 11th February 2019

Avalanche Danger Ratings Mon 11th Feb 3:35PM Danger Ratings Alpine: Moderate Danger Ratings Treeline: Moderate Danger Ratings Below Treeline: Low Wind Slabs Wind Slabs

Avalanche Canada Forecaster: dsaly

Date Issued:

Valid Until:

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.

Confidence

Moderate - Forecast snowfall amounts are uncertain on Tuesday

Weather Forecast

MONDAY NIGHT: Cloudy with clear periods, isolated flurries with trace to 5 cm accumulation. Alpine temperatures near -19C. Ridgetop winds moderate from the east.TUESDAY: Mostly cloudy with isolated flurries, 5-10 cm accumulation. Alpine temperature near -12C. Ridgetop winds moderate from the east.WEDNESDAY: Mix of sun and cloud. Alpine temperatures near -10C. Ridgetop winds light from the southwest.THURSDAY: Sunny with cloudy periods, flurries starting later in the day. Alpine temperature near -8C, freezing level rising to 600 m. Ridgetop winds moderate from the south-southeast.

Avalanche Summary

Small pockets of wind slab have been reactive to skier traffic in steep and immediate lee features. Of note is a MIN from the Whistler backcounty reporting wind slabs at lower elevations and in more sheltered terrain than usual (see the MIN here).On Sunday, explosives work on cornices failed to initiate any wind slabs on the slopes below. Otherwise, no new natural avalanches have been observed recently.

Snowpack Summary

A dusting of snow fell on variable wind-pressed, wind-sculpted, exposed crust and windslab surfaces cover the 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 0-80 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 above 1800m. 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. The remainder of the snowpack is generally well-settled.

Wind Slabs Wind Slabs

Likelihood

Likely - Possible

Expected Size

1 - 2

Widespread wind effect is found in the region with more reactive wind slabs in steeper features and lee-terrain. 10 cms of snow is forecasted through Tuesday with moderate winds. Expect redistributed new snow be most reactive in wind-loaded terrain.

Watch for whumpfing, hollow sounds, and shooting cracks.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.The recent snow may now be hiding windslabs that were easily visible before the snow fell.

Aspects: All aspects.

Elevations: Alpine, Treeline.

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