Bulletin d’avalanche

Seeley Lake

West Central Montana Avalanche Center
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Danger d’avalanche

Wed
Alpin
2 · Modéré
Limite forestière
1 · Faible
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 5 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

The rating is Moderate at upper elevations in the Seeley Lake zone and Low in the rest of the forecast area. The snowpack is generally stable. The exception is ridgelines above 6500’. A skier or rider could trigger wind-loaded pockets in terrain over 35º. Terrain traps and committing terrain will increase the consequences of a slide. 

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    Windslab can be found throughout the forecast area at upper elevations, below exposed ridges. The southern Missions have the most concerning windslab, with multiple avalanches from over the weekend reported. Some took place on rounded treed ridges that were not obvious avalanche terrain and had crowns up to two feet thick. While bonding has taken place, reactive windslab remains.

    It is possible to trigger a windslab in the Seeley Lake zone that could bury, injure or kill a person. Easterly slopes are the most likely place to find these, but cross-loading on other aspects is possible. Watch for wind lips and pillows around gullies that indicate wind transport and loading. 

    The likelihood of triggering wind slab is low in the rest of the forecast area but not impossible. 

    Always approach wind-loaded slopes with suspicion. Test small, safe, representative slopes for reactivity before stepping into bigger terrain. Travel one at a time. 

     

Avalanche Discussion

A quick storm yesterday brought a very welcome refresh of snow. Up to 4” fell with the Rattlesnake being favored. Winds were light to moderate during the storm, with upper elevations receiving the strongest gusts. There was some snow transport, but wind slab remained small and isolated. 

Strong winds over the weekend were evidenced by extensive wind-affected surfaces throughout the forecast area. The debris from multiple natural windslab avalanches were found yesterday in the Seeley Lake zone. Stiff windboard and scalloped surfaces affected skiing and riding quality in other places. 

Overnight winds were northerly and light with strong gusts. No new snow fell. An inversion today means sunny warm mountains and cool valleys. Expect sun warming of southern aspects. 

Today the conditions are mostly stable. Overall we are finding a very well consolidated right side up snowpack. However, there are two exceptions:

  1. Wind slab at upper elevations. In the southern Missions, these are more reactive and common on easterly slopes. Elsewhere in the forecast area, windslab is isolated and stubborn
  2. The deeply buried facets in the southern Bitterroot are still failing in tests in certain places. Above 7400’ on shaded aspects, we are still finding spots where the propagation saw test (PST) shows a likelihood of propagation. This is a very low likelihood but high consequence layer. It last failed on Dec. 22nd. It weathered the January 5 to 8 storm and following warm weather without failing, indicating it is very stubborn and unlikely to avalanche naturally. As such, we are not adding it back in as a problem but will keep an eye on how it develops. This could be the sort of layer to reawaken late in the season with significant weather or warming. There is a very slight chance that skiers and riders could find a trigger spot for this layer in shallow windswept or rocky areas. 

Remember that Low danger does not mean no danger. There are always exceptions to the rating, and isolated pockets of instability could be lurking. Continue to take care in the mountains. Watch for red flags and travel one at a time in avalanche terrain.

Please submit your observations. They help us provide a more thorough and accurate forecast. You can submit them here.

Ski and ride safe. 

Régions couvertes