Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Dec 2nd, 2018–Dec 3rd, 2018

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Lizard-Flathead.

Uncertainty exists around the buried weak layers in the snowpack. Human triggers are still possible, especially where the slab sits above a weak layer. If the sun comes out, heads up on sun-exposed slopes for loose wet avalanches.

Confidence

Moderate - The weather pattern is stable

Weather Forecast

MONDAY: Cloudy in the morning with sunny skies in the afternoon/ alpine temperatures near -9/ generally light winds from the West/ freezing level valley bottomTUESDAY: Mix of sun and cloud/ alpine temperatures near -12/ ridgetop winds light from the West/ freezing level valley bottomWEDNESDAY: Sunny with some clouds/ alpine temperatures -12/ ridgetop winds light from the northeast/ freezing levels valley bottom

Avalanche Summary

On Sunday, a human triggered avalanche size 1.5 was reported. This ran on a northwest aspect at 2300 m. The crown was 15 cm, 20 m wide and ran 300 m. Explosive control also triggered a few storm slabs up to size 2 from northeasterly aspects 1800-2000 m. Check out the initial report here.On Monday, If the sun comes out the surface snow may become wet and deteriorate on sun-exposed slopes. Loose wet avalanches may occur.Even though the avalanche hazard has decreased I suspect human triggered avalanches will be possible, especially where the storm slab sits above a weak layer like surface hoar or the early November crust. If you're in the backcountry and have observations to share, please post to the Mountain Information Network.

Snowpack Summary

Up to 55 cm of recent snow sits on a series of crusts and a feathery surface hoar layer. A predominant crust can be found below this recent snow at treeline and into the alpine on all aspects. Reports indicate that the slab above this crust may be more reactive on northerly aspects. I would investigate this bond before jumping onto large, planar terrain features. We have a lot of uncertainty around this weak surface hoar layer, its distribution is spotty. I suspect that it could exist on sheltered slopes in the alpine and at treeline. At the bottom of the snowpack you'll likely find another crust and sugary weak facet crystals around it. At treeline the average snowpack depths are 80 cm. These depths taper rapidly at lower elevations.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.