Lawinenlagebericht

Central Sierra Nevada

Sierra Avalanche Center
Auf der Karte ansehen

Lawinengefahr

Hochgebirge
1 · Gering
Waldgrenze
1 · Gering
Unterhalb
1 · Gering
Veraltet — dieser Lagebericht ist 6 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Shallow early season conditions with lots of exposed and barely covered obstacles to hit will represent today's main concern. Avalanche activity has become unlikely on a regional scale. Unlikely does not mean impossible and overhangs of snow along ridges or a patch of unstable snow on an isolated terrain feature could still cause trouble today. LOW avalanche danger exists at all elevations. 

Lawinenprobleme

  • Cornices

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    1

    Data and observations seem to indicate that the thin snowpack has gained enough strength to support itself and triggering an avalanche has become unlikely in the majority of the forecast area. The caveat to this is that instability like fragile overhangs of snow along ridgelines (cornices) or a small area unstable of snow on some isolated terrain feature may still exist. A thin snowpack and numerous exposed and barely covered rocks, stumps, logs, bushes, and other obstacles more than makeup for the decreased instability. 

    It pays to be conservative when traveling in a thin snowpack since collisions with hard immovable objects tend to damage people and equipment. Sometimes these things stick up out of the snow. Sometimes they lurk just below the surface. Moving on low angle slopes at slower speeds and maintaining constant vigilance can help. Early season also represents a great time to practice avalanche rescue skills, route finding, and terrain identification. Start the season off by practicing safe travel strategies and make them a habit for the rest of the year.

Avalanche Discussion

Yesterday, snowpit data and observations from Relay Peak targeting the old weak snow near the base of the snowpack showed definite improvement over observations in the same area on 11/18. Yesterday that weak layer exhibited no signs of instability and none of the snowpit tests produced unstable results. Other observations from Tamarack Peak and in the Donner Summit area also did not find any lingering signs of instability associated with this layer. These observations continue a trend evidenced by data gathered on 11/19 and 11/20 at a variety of locations showing that the old weak snow is gaining strength and seems able to support the more recent snow above it now. This layer will continue to change and continued monitoring will tell if it starts to weaken again. 

Observations on Relay Ridge yesterday and Meiss Ridge and Donner Summit on 11/19 did not find any signs of wind slab instability. 

Other observations in the Mt. Rose backcountry and on Donner Summit found soft cold snow and surface hoar on more northerly aspects and warmer, sometimes wet and sticky sometimes crusty snow on sunny easterly and southerly aspects.

The snowpack remains thin with numerous things to hit. The best coverage exists above 7800’ along the Sierra Crest and above 8600’ in the Mt. Rose area.

Bushes and rocks poking out of the snowpack on Relay Peak at about 9500 ft.

Abgedeckte Regionen