Avalanche Forecast

Issued: Nov 23rd, 2017 4:24PM

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

Avalanche Canada mconlan, Avalanche Canada

Conservative travel is recommended at all elevations because of generally poor snow quality and uncertainty from limited data.

Summary

Confidence

Low - Due to the number of field observations on Friday

Weather Forecast

Cooler temperatures with light flurries are expected Friday and Saturday until the next warm and wet storm on Saturday night and Sunday.FRIDAY: Cloudy with flurries, accumulation 5-15 cm / Moderate to strong southwest winds / Alpine temperature -7 C / Freezing level 1300 mSATURDAY: Cloudy with light flurries, accumulation 2-5 cm / Moderate to strong southwest winds / Alpine temperature -5 C / Freezing level 1500 mSUNDAY: Flurries in the morning and rain in the afternoon, accumulation 10-20 mm / Strong southwest winds / Alpine temperature 0 C / Freezing level 2000 m

Avalanche Summary

Many natural and explosive-controlled avalanches were observed on Wednesday and Thursday. Loose wet avalanches were generally size 1 and 2 and most often observed at treeline and alpine elevations and on all aspects. The slab avalanches were generally size 2-3 and between 1700 and 2700 m on all aspects. The natural avalanche activity should decrease into Friday with the cooler temperatures and decreased precipitation.

Snowpack Summary

The wet weather on Thursday dropped around 30 mm of rain onto the snowpack, likely to mountain top for most of the region. Rain switched to snow Thursday afternoon, which may not bond well to the underlying wet snow. Deeper in the snowpack, there are two weak layers, including a layer down around 50 to 80 cm at treeline elevations as well as a crust with weak facets around it down around 80 to 130 cm. The layer down 50 to 80 cm may be more prominent in the northern area of the forecast region and the crust may be widespread across the forecast region. Both layers may not be as prominent below treeline, particularly below 1500 m. There is much uncertainty with the spatial variation of these layers, largely because of limited data in the forecast region.

Problems

Wind Slabs

An icon showing Wind Slabs
New snow has fallen with moderate to strong winds. Wind slabs are expected in lee terrain features.
Use caution in lee areas. Recent wind loading has created wind slabs.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs
Rain and snow have loaded the snowpack. A person or machine could trigger an avalanche in areas where a weak layer remains intact, particularly where the snowpack is thin.
Avoid steep convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Nov 24th, 2017 2:00PM

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