Bulletin d’avalanche

West Slopes Central

Northwest Avalanche Center
Voir sur la carte

Danger d’avalanche

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

Points saillants

 

Danger from wet avalanches is decreasing in most areas. Evaluate conditions as the day warms and be prepared to change course if you make observations different from expected. Check the forecasts for Stevens or Snoqualmie Passes if traveling in areas adjacent to those zones.

 

Problèmes avalancheux

  • Loose Wet

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

    Areas south of the Mountain Loop that received 6-12” of new snow on Thursday are where there is the greatest likelihood of encountering a loose wet avalanche. South facing slopes near treeline are the most suspect. At that elevation, there could be enough new snow to avalanche compared to below treeline where there is minimal new snow and the surface is a supportable, frozen crust. Significant warming is more likely near treeline than above due to moderate alpine winds and dropping freezing levels. Avoid travel on and under steep terrain when the snow surface warms and becomes unsupportable. Choose terrain based on options to minimize exposure to loose wet avalanches. If you find a thick crust topping snow surfaces, then loose wet avalanches are unlikely.

    (1/22/2022)

    Small wet loose avalanche off steep south facing terrain on Lichtenberg Mtn.

    Photo: Matt Primomo

Avalanche Discussion

No recent avalanche activity was noted on Sunday but observers at Stevens Pass noted very warm temperatures at pass level with rollerballs even on slopes in the shade at lower elevations. On Saturday in the same zone, observers reported a handful of wet avalanches on steep sunny slopes.

Farther north conditions were less active with little new snow on the surface and minor melting. No avalanches were reported over the weekend with only minimal heat related instabilities (like rollerballs) reported on solar aspects. Observations indicate the snow surface remained frozen.  The exception was in terrain receiving strong sun where the crust softened - but still remained supportable.

Large glide cracks and “wrinkled” snow surfaces abound in some areas, especially in rocky, rugged terrain. These features indicate where the entire snowpack is slipping on the smooth ground below and could potentially avalanche. Even with Low danger, there is still a chance one or more of these could sporadically release in isolated terrain features. The likelihood is greatest on sun-warmed slopes near treeline, but glide avalanches can release at any time. Identify and minimize time spent below these features, cornices, or anything else that looks unstable and poorly attached to the rest of the slope. Danger from all the above will persist until temperatures cool.

At the highest elevations, small wind slabs could still present risk in steep, exposed terrain. Identify and evaluate wind loaded terrain before moving onto consequential slopes.                                             

This weekend brought a combination of the strongest sun and warmest temperatures yet this year.  On the other hand, we have a very strong rain affected snowpack capped with a stout crust that has resisted significant melting. Between the solid snowpack (bring a pickaxe to dig a pit), low January sun, and other factors that inhibited melt, the big warm-up delivered no increase in avalanche danger. This could change in the coming week with continued above freezing temperatures. 

Expect challenging travel conditions on frozen, uneven surfaces. If you haven’t made it to the mountains since the rain and then high pressure took over, be prepared to see a very different environment. Exposed rock, glide cracks, open creeks, and a rough snow surface all present new hazards to avoid.

Régions couvertes