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Avalanche Forecast

Archived

Jan 11th, 2023–Jan 12th, 2023

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

Regions

Lizard-Flathead, Flathead, Lizard, Moyie.

Likelihood of triggering deep persistent layers may be decreasing, however, they remain a primary concern. Specifically in shallow, variable, rocky terrain.

Confidence

Moderate

Avalanche Summary

Several natural storm slab avalanches were reported throughout the lizard range on Monday. Generally occurring above 1900 m on northerly terrain. Size range from 1 to 2.

Please continue to share any observations or photos on the Mountain Information Network.

Snowpack Summary

The upper snowpack continues to settle and stabilize. A widespread melt-freeze crust is buried by roughly 40 to 80 cm. The crust ranges in thickness from 1 cm at higher elevations to 20 cm thick at lower elevations. The mid-snowpack is generally well consolidated below the crust. A weak layer of large facets and a crust persists down 70 to 150 cm from the surface. The snow below the crust is generally weak and unconsolidated.

Treeline snow depths are roughly 150 to 200 cm.

Weather Summary

Wednesday night

Cloudy with isolated flurries, and trace snow. Light to moderate southwest ridgetop winds. Treeline temperatures -5 to -10 C.

Thursday

Mostly cloudy with flurries, and trace snow. Light to moderate southwest ridgetop winds. Treeline temperature -0 to -5 C.

Friday

Cloudy with light snow, 0 to 5 cm. Moderate southwest ridgetop winds. Treeline temperatures around 0 C. Freezing levels 2100 m.

Saturday

Cloudy with snow, 2 to 10 cm. Moderate southwest ridgetop winds. Treeline temperatures around 0 C. Freezing levels 1700 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Conditions may have improved, but be mindful that deep instabilities are still present.

Problems

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.