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Archived

Avalanche Forecast

Feb 14th, 2019–Feb 15th, 2019
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
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
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
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: South Rockies.

A storm is incoming, but total snowfall amounts for Thursday night into Friday are uncertain. The forecast herein assumes 30+ cm of snow accumulation by Friday afternoon.

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

THURSDAY NIGHT: Cloudy with snowfall, accumulation 10 to 20 cm, alpine temperature -10 C.FRIDAY: Cloudy with snowfall, accumulation 5 to 15 cm, moderate to strong southwest wind, alpine temperature -10 C.SATURDAY: Cloudy with snowfall, accumulation 10 to 20 cm, light to moderate west wind, alpine temperature -16 C.SUNDAY: Mostly cloudy with light snowfall, accumulation 5 cm, light north wind, alpine temperature -23 C.

Avalanche Summary

Many large avalanches were triggered naturally, by explosives, and by skiers and sledders on Wednesday. The avalanches were generally within the recent storm snow, around 30 to 60 cm deep, and at treeline and alpine elevations.

Snowpack Summary

More snowfall is expected Thursday night into Friday, with total amounts uncertain but could be upwards of 20 cm or more. The snow may have slab properties where it falls with wind and could be low-density and loose in sheltered areas. This new snow will overly around 20 to 40 cm of recent snowfall, which sits on a variety of surfaces, including wind-affected snow in exposed areas and a layer of weak and feathery surface hoar crystals in sheltered and shaded areas. Below 1700 m, recent snowfall overlies a melt-freeze crust.The mid-January layer of surface hoar or a crust is buried around 50 to 80 cm. The surface hoar is found on shaded and sheltered slopes and is most prominent between 1600 m and 1900 m but has been found up to 2200 m. The melt-freeze crust is found on south aspects at all elevations.The middle of the snowpack is generally consolidated. The bottom half of the snowpack is unconsolidated and composed of weak and sugary faceted grains.

Avalanche Problems

Storm Slabs

More snow is forecast Thursday night, but there is uncertainty in the amounts. It could be 10 cm or could be 30+ cm. Avoiding avalanche terrain is the prudent choice. This snow could form large avalanches and step down to deeper weak layers.
A good day to avoid avalanche terrain.If triggered, storm slabs may step down to deeper layers resulting in very large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 2.5

Persistent Slabs

A weak layer of surface hoar is buried around 50 to 80 cm, which is best preserved in shaded and sheltered areas between 1600 m and 1900 m. The likelihood of triggering this layer will increase with further snow load.
A good day to avoid avalanche terrain.Below treeline, use added caution in open terrain features such as cutblocks, gullies, and cutbanks.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood: Possible - Likely

Expected Size: 1.5 - 3