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

Jan 14th, 2019–Jan 15th, 2019

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

Regions

Lizard-Flathead.

Some avalanche danger remains in alpine areas, in wind loaded pockets and on steep, thin/rocky slopes.

Confidence

High -

Weather Forecast

MONDAY NIGHT: Clear skies. Temperatures dropping to around -14C.TUESDAY: Dry and sunny above some valley cloud. Expect cool treeline and alpine temperatures, around -4C. Calm winds.WEDNESDAY: Dry with a mix of sun and cloud. Treeline temperatures around -6C. Light southwesterly winds.THURSDAY: Light snowfall, 2-4 cm. Treeline temperatures around -9C. Light easterly winds.

Avalanche Summary

On Saturday control work produced wind slab avalanches to size 2 on northeast facing features. A size 2 natural deep persistent slab was also reported on a south facing aspect around 2100 m. We're very grateful that a group of sledders shared a fantastic MIN report about their near miss here. A large avalanche was triggered on a thin, rocky, southwest facing feature near ridgecrest, the photos tell a compelling story about the structurally weak snowpack that exists in many places in the region. On Friday natural avalanches size 1.5 to 2 were reported from northeast through northwest facing terrain at and above treeline. Control work produced storm slab avalanches to size 2.5 on similar aspects. Control work also caused cornices to fail on southeast facing terrain which subsequently produced storm slab avalanches to size 1.5.

Snowpack Summary

Recent sunshine and warm alpine temperatures have created moist/crusty surfaces on solar aspects. The snow appears to have remained dry on shady aspects. Wind slabs have become difficult to trigger.In shallow snowpack areas, the base of the snowpack may still be composed of weak faceted grains. In deeper snowpack areas, the middle and lower portions of the snowpack are generally considered to be well-settled and strong.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.