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Avalanche Forecast

Archived

Feb 21st, 2025–Feb 22nd, 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 and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.

Regions

Lizard-Flathead, Flathead, Lizard.

6:30 AM Update: Storm delayed until this evening.

Temperatures will still rise and persistent slabs may become more reactive.

Confidence

Low

Avalanche Summary

On Thursday, a size 1.5 naturally-triggered wind slab was reported in the Lizard Range on a north-facing slope.

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

On Tuesday there were two reports of size 1.5 skier and snowmobile triggered persistent slab avalanches in the alpine. See details in this MIN here as well as this MIN.

Snowpack Summary

Around 5 to 15 cm of new snow is expected to fall overnight and through Saturday, with the highest amounts forecast for the Lizard Range. This will add to the current 20 to 30 cm of more recent snow overlying 30 to 60 cm of facets. Below this is a persistent weak layer consisting of a crust or 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

Friday Night

Cloudy with 5 to 10 cm of snow. 30 to 40 km/h southwest ridgetop wind. Treeline temperature -4 °C.

Saturday

Cloudy with 2 to 5 cm of snow. 30 to 40 km/h southwest ridgetop wind. Treeline temperature -1 °C. Freezing level rising to 1800 m.

Sunday

Mostly cloudy with 15 to 25 cm of snow or rain below 1700 m. 40 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing level rising to 2000 m.

Monday

Mainly cloudy with 0 to 5 cm of snow or rain below 1400 m. 30 to 50 km/h southwest ridgetop wind. Treeline temperature -4 °C. Freezing level rising to 1700 m.

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.
  • Pay attention to the wind; once it starts to blow, sensitive wind slabs are likely to form.
  • Be especially cautious as you transition into wind-affected terrain.

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.

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.