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Avalanche Forecast

Nov 23rd, 2017–Nov 24th, 2017
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: North Columbia.

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

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.

Avalanche Problems

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

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