Avalanche Forecast

Issued: Mar 21st, 2018 6:09PM

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

Avalanche Canada ghelgeson, Avalanche Canada

Watch for deteriorating avalanche conditions and steadily increasing hazard throughout the day. Both natural and human triggered avalanches will become increasing likely, especially in wind exposed terrain at and above treeline.

Summary

Confidence

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

Weather Forecast

A rather complex pattern is expected to deliver a significant shot of precipitation and wind with a warm to cold trend. This storm should be most intense Thursday and begin to clear as we enter the weekend. This is a great time to check out the Mountain Weather Forecast for further details! (Link below)WEDNESDAY NIGHT: Freezing level around 1600 m, strong to extreme southerly wind, 1 to 5 mm of precipitation. THURSDAY: Overcast, freezing level starting at 1600 m, lowering to 1000 m by sundown, moderate to strong south/southwest wind, 4 to 12 mm of precipitation possible. FRIDAY: Scattered cloud cover, freezing level beginning around 500 m rising to 1000 m, moderate southerly wind, 1 to 2 mm of precipitation possible.SATURDAY: Scattered cloud cover, freezing level beginning around 500 m rising to 1400 m, light variable wind, no significant precipitation expected.

Avalanche Summary

No new avalanche observations to report from Monday or Tuesday.On Sunday another skier triggered avalanche was reported from around the Duffey on a north/northeast facing feature between 1900 and 2000 m. The size 2 avalanche failed on the March 8th surface hoar with a crown depth of 20 cm. Small loose wet avalanches were also triggered by direct solar input in steep rocky terrain.On Saturday two size 1.5 skier triggered avalanches were reported from steep northeast facing terrain at 2200 m on the Duffey. The slabs were up to 20 cm in depth, failing on the March 8th surface hoar.We received a great MIN report on Saturday that details a size 3 skier triggered avalanche on the northwest face of Matier that likely occurred in the last few days. More details here.

Snowpack Summary

New snow Thursday will fall on a slippery crust that is present at all elevations on solar aspects. Low elevation polar aspects also have a crust, but treeline and alpine elevations feature a mix of large surface hoar and surface facets.In the north of the region, polar aspects (those that face north and east) are harboring cold snow and a tricky buried surface hoar interface down 20 to 40 cm below the surface. The layer is widespread in the alpine and at treeline, but it is not everywhere. This layer has recently produced large human triggered avalanches in the north of the region as detailed above. This layer has not been reactive in the south of the region. Also in the north of the region a weak layer buried mid-February is about 40 to 50 cm below the surface and has been reactive in snowpack tests. The layer is composed of sugary facets, a sun crust on solar aspects, and surface hoar that is present at and below treeline. The snowpack is well settled in the south of the region around the Coquihalla and in Manning Park.

Problems

Storm Slabs

An icon showing Storm Slabs
Natural and human triggered avalanches are expected to increase in size and sensitivity to triggering throughout the day. Storm slabs in motion may initiate large avalanches failing on buried surface hoar 20 to 40 cm below the surface.
Storm slabs are expected to be most sensitive to triggering in wind exposed terrain.Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.Avoid open slopes and convex rolls at treeline where buried surface hoar may be preserved.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Valid until: Mar 22nd, 2018 2:00PM

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