Avalanche Forecast

Issued: Feb 14th, 2019 4:22PM

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

Avalanche Canada shorton, Avalanche Canada

Danger ratings are for southern parts of the region where more snow is expected on Friday. Northern parts of the region are similar to the Sea-to-Sky region, where wind slabs are the main concern.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Friday

Weather Forecast

THURSDAY NIGHT: 10 cm of snow in south parts of the region (e.g. Coquihalla/Manning) and 5 cm further north, moderate southwest wind, alpine temperatures drop to -7 C.FRIDAY: Another 10 cm of snow in the south and trace amounts in the north, moderate southwest wind, alpine high temperatures around -3 C in the south and -6 C in the north.SATURDAY: Mix of sun and day with some isolated flurries, light wind, alpine high temperatures around -5 C.SUNDAY: Sunny with cloudy periods, light wind, alpine high temperatures around -10 C.

Avalanche Summary

On Wednesday, numerous size 2 loose dry and storm slab avalanches were reported on all aspects in the south of the region, particularly in the Cheam area where the storm slabs were thicker.On Tuesday, a size 2 natural wind slab was observed on a south-facing slope around 2000 m. Loose dry avalanches were also widespread.Wind slab avalanches were widespread over the weekend with two significant incidents being reported on the MIN. We really appreciate that the parties involved posted this information so we can all learn from it. Check out this MIN from the Backside of Heartstrings, and this one from Channel. These incidents show how widespread the wind effect was in the region.

Snowpack Summary

In southern parts of the region expect roughly 20 cm of new snow on Friday to form fresh slabs, particularly on wind loaded terrain features. Elsewhere in the region, less snow is expected, so the surface will be heavily wind-affected from recent strong winds (from the north-northeast-east-southeast).Due to the scouring and wind-loading, anywhere from 0-60 cm of snow sits on a crust on all aspects below 2000 m and on solar aspects into the alpine. Above 1800 m, recent cold temperatures have been working to facet and break down the crust. In sheltered terrain at and below treeline, a layer of weak feathery surface hoar or sugary facets may be identified, but this interface has produced little recent avalanche activity. A crust that formed in mid-January is now 50 to 80 cm below the surface. This crust is present right to mountain top on southerly aspects and on all aspects below 1700 m. The remainder of the snowpack is generally well-settled.

Problems

Storm Slabs

An icon showing Storm Slabs
Fresh storm slabs may form in southern parts of the region on Friday. Elsewhere, strong wind has formed wind slabs in exposed terrain. Recent snow may overlie a crust on south-facing features, which may increase the likelihood of human triggering.
Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Minimize exposure to steep planar south-facing slopes.Minimize exposure during periods of heavy loading from new snow and wind.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Feb 15th, 2019 2:00PM

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