Bulletin d’avalanche

Central Sierra Nevada

Sierra Avalanche Center
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Danger d’avalanche

Sat
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Rapid warming and decreasing winds today will allow for unstable wet snow to form in sun exposed areas. Watch for developing signs of unstable wet snow such as rollerballs, pinwheels, or wet loose avalanches. Move to lower angle slopes if these signs of instability are present.

Problèmes avalancheux

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    Cooler air temperatures over the past few days have allowed recent new snow to escape melt-freeze in many areas. Today's rapid warming, a substantial increase in maximum daytime air temperatures, and decreasing winds will allow snow surface melt to affect this recent new snow. As this recent new snow warms on sun exposed slopes, it is expected to become unstable. The vast majority of surface wet snow development will occur across ENE-SE-S-SW-WNW aspects. The sun angle is starting to get high enough to have more effect on some NE and NW aspects so treat all sun exposed slopes with caution today. Pay particular attention to terrain where shallow amounts of wind drifted snow from yesterday and steep sun exposed slopes intersect.

    Rollerballs, pinwheels, and wet loose avalanches are all signs of unstable wet snow. When these signs of instability are present, move to lower angle slopes without steeper terrain above. Instability will increase as daytime warming progresses through the late morning and afternoon hours. Time travel in or below avalanche terrain accordingly.

    Rollerballs and pinwheels on NE to E aspect terrain. A sign of potentially unstable wet snow.

Avalanche Discussion

  • Strong NE winds over the past 24 hours scoured and drifted small amounts of snow in near and above treeline areas. Any lingering unstable wind slabs should be small.
  • Snowmelt on SE-S-SW aspects has exposed bare ground in many areas. Over snow travel options are limited on these aspects.
  • The old near surface facet layer that was buried on Feb 14 following the prolonged Jan/Feb dry spell continues to gain strength in most areas. Isolated pockets where this layer remains drier and weaker with the potential future ability to collapse and propagate exist in well shaded areas.  We still need a sizable loading event to create an avalanche problem on this weak layer.

Régions couvertes