Avalanche Forecast

Issued: Apr 14th, 2018 4:04PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs and Persistent Slabs.

mconlan, Avalanche Canada

South Coast Inland.

More snow forecasted in the south of the region Saturday night will keep the hazard at Considerable. Observe for the bond of the snow with the underlying crust before committing into avalanche terrain. Be particularly cautious if the sun comes out.

Summary

Confidence

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

Weather Forecast

SUNDAY: 10 to 20 cm snowfall in the south of the region early-morning, otherwise a mix of sun and cloud with late-afternoon snowfall, light northeast winds, alpine temperature -4 C, freezing level 1500 m.MONDAY: Cloudy with snowfall, accumulation 15 to 20 cm, light west winds, alpine temperature -5 C, freezing level 1400 m.TUESDAY: Mostly cloudy, light west winds, alpine temperature -5 C, freezing level 1500 m.

Avalanche Summary

Numerous small wind slab avalanches were triggered by skiers on Friday, 20 to 35 cm deep and on northerly aspects in alpine terrain. These were running within the recent storm snow on the melt-freeze crust. They were reported as easy to initiate, indicating that the bond between the new snow and the crust is poor.

Snowpack Summary

Around 30 to 50 cm of snow has fallen in the region between Thursday and Saturday. This snow overlies a thick and hard melt-freeze crust. On ridges, cornices are reported to be large and fragile. At low elevations below treeline, recent rain has created moist or wet snow conditions.A weak layer consisting of surface hoar, facets, and/or a melt-freeze crust from late March is now buried about 50 to 100 cm. This layer is spotty in its distribution. It is mostly likely to be problematic on west, north, and east aspects between 1900 m and 2250 m.The mid and lower snowpack are well-settled and strong.

Problems

Storm Slabs

Recent snow has created slabs that are not bonding well to a crust. The slabs are particularly reactive in lee features, as the snow fell with strong south winds. Slab and loose avalanches will become more likely on south slopes if the sun comes out.

Avoid steep slopes when air temperatures are warm or the solar radiation is strong.Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.Use ridges or ribs to avoid pockets of wind-loaded snow.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2.5

Persistent Slabs

A weak layer buried 50 to 100 cm is still surprising people and producing large and destructive avalanches in the north of the region. Be particularly cautious around upper treeline and alpine terrain on shady aspects.

Pay attention to overhead hazards like cornices, which could trigger persistent slabs.Avoid steep terrain or areas with a thin or variable snowpack.Be aware of the potential for wide propagation due to the presence of buried weak layers.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Apr 15th, 2018 2:00PM