Avalanche Forecast
Issued: Dec 11th, 2019 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Wind Slabs and Persistent Slabs.
ahanna,
Avalanche Canada
The Monashees in the north of the region will see enhanced snowfall amounts compared to the rest of the region. Reactive storm slabs building through the day will elevate the danger rating to Considerable at alpine and treeline in this area.
Summary
Confidence
Weather Forecast
Wednesday Night: Mainly cloudy with flurries starting, accumulating up to 10 cm by morning in the monashees in the north of the region. Alpine low -6, moderate southwest wind increasing to strong overnight.
Thursday: Flurries in the morning accumulating 5-10 cm, with evening flurries in the south of the region. Alpine high -3, moderate southwest wind gusting to strong.
Friday: Cloudy with scattered flurries accumulating 5-10 cm, alpine high -3, light northwest wind.
Saturday: Cloudy with scattered flurries accumulating 5 cm, alpine high -3, light northwest wind.
Avalanche Summary
Natural and skier triggered windslab and persistant slab avalanches averaging size 2 have been widely reported in the north of the region and in neighboring Glacier National Park. Natural events have been reported on a range of aspects and are suspected to have been triggered by wind loading or solar radiation.
Snowpack Summary
Large, feathery surface hoar crystals have been observed on the snow surface at all elevations throughout the region, and are now covered by 3-5 cm of snow. As new snow falls on this layer over the day Thursday, reactive storm slabs may build in areas of higher snowfall.
Soft wind slab can be found in the lee of features such as ridge tops, ribs and gulleys. In more sheltered areas, the upper snowpack remains soft and unconsolidated in the cool temperatures.
A weak layer formed in late November is now buried 60-100 cm below the surface. This is the layer of concern relating to the persistent slab avalanche problem. The weak layer may present as surface hoar, a crust, facets or a combination, depending on elevation and aspect. It can most likely be found in areas sheltered from the wind, but open to a view of the sky, such as near treeline. Below this, variety of crusts from late October are buried deeper in the snowpack.
Problems
Storm Slabs
Reactive storm slabs may build over the day Thursday in the Monashees in the north of the region, where snowfall amounts are forecast up to 20 cm. The new snow will fall on large, feathery surface hoar crystals have been observed on the snow surface at all elevations throughout the region. This can be a recipe for remote triggering and wide propagation in the storm snow.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Wind slabs can be found in lees of features such as ridgetops, ribs and gullies. Windslab avalanches have surprised a number of skiers in recent days.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
This weak layer formed in late November may present as surface hoar, a crust, facets or a combination, depending on elevation and aspect. It is buried 60-100 cm below the surface and can most likely be found in areas sheltered from the wind, but open to a view of the sky, such as near treeline.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 12th, 2019 5:00PM
