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Avalanche Forecast

Archived

Feb 19th, 2025–Feb 20th, 2025

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

Regions

Lizard-Flathead, Flathead, Lizard.

Watch for persistent slabs to become more reactive as a gradual warming trend continues over the next few days.

Confidence

Moderate

Avalanche Summary

There have been numerous, small to large (size 1 to 2) dry and wet loose avalanches, both natural- and rider-triggered running in steep terrain over the past few days.

There were two reports of size 1.5 skier and snowmobile triggered persistent slab avalanches on a southeast and northwest aspects in the alpine. See details in this MIN here as well as this MIN here.

Snowpack Summary

20 to 30 cm of snow has fallen since last Friday. This storm snow is sitting on 30 to 60 cm of faceted old snow. Below this is a persistent weak layer consisting of facets and surface hoar buried in late January.

The mid and lower snowpack is generally well settled, with no other layers of concern.

Weather Summary

Wednesday Night

Cloudy with 1 to 3 cm of snow. 20 to 40 km/h southwest ridgetop wind. Treeline temperature -8 °C.

Thursday

Mainly cloudy. 20 to 40 km/h west ridgetop wind. Treeline temperature -5 °C.

Friday

Mostly cloudy with isolated flurries. 30 to 50 km/h southwest ridgetop wind. Treeline temperature -3 °C.

Saturday

Mostly cloudy with 2-5 cm of snow. 30 to 60 km/h southwest ridgetop wind. Treeline temperature -1 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
  • Make observations and continually assess conditions as you travel.
  • Loose avalanches may step down to deeper layers, resulting in larger avalanches.

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 Dry

Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.