Avalanche forecast

Eastside Region

Eastern Sierra Avalanche Center
View on map

Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
Open full map
Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Large, unstable wind drifts have formed in the last 24 hours on a variety of snow surfaces, and have loaded the weak layers at the base of our snowpack. You’re most likely to encounter these hazards near steep wind-loaded areas, and where the snowpack is generally shallower. Stick to slopes less than 30º with no overhead hazard to minimize your exposure today.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5

    South - Southwest winds have been consistently blowing snow for the past 24 hours. With ample snow available for transport, unstable wind drifts have developed at all elevations on leeward slopes. Winds continued to howl overnight as certain areas in the region received new snow, allowing for even larger wind slabs to form. Blowing snow and cornice formation are key indicators of wind slab formation. Hollow, stiff, textured snow can clue you into where this problem lies. You’ll likely find it beneath ridgelines, in gullies, on open slopes, in cross-loaded bowls, and in open areas below treeline. These wind slabs have developed on a variety of surface types which may affect their reactivity. We are thinking both natural and human-triggered wind slabs are on the menu today. It is important to remember that a wind slab avalanche could step down to our buried weak layers and trigger an avalanche involving the entirety of our snowpack. Stick to low-angle terrain without overhead hazards to minimize your exposure.

    (2/14/2024)

    Blowing snow visible at all elevations, and even in areas with minimal snow available for transport. Winds are moving snow over long distances today. 

    Photo: Samantha Rubin

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–3

    We are still talking about buried weak layers at the base of our snowpack. Depth hoar and buried facets have shown variability in depth and structure throughout our forecast region. In areas where the snowpack is generally deeper, such as along the crest, and in the Mammoth and June Lake areas, we are seeing limited signs of instability, such as cracking and wumpfing. However, the weak structure still exists, and is vulnerable to human trigger near shallowly buried trigger points, and natural loading. An avalanche on these layers in these areas could break deeper than 6 ft, and would almost certainly be unsurvivable. 

    In other areas where the snowpack is generally shallower, we have seen reactivity in response to loading, including wumpfing, cracking, and slopescale collapsing. An avalanche on these weak layers could be fairly easy for a human to trigger, and is more susceptible to failing naturally under a new load. Be wary of shallowly buried trigger points such as rocks, bushes, steep rocky faces, and convexities, as well as wind loaded areas and the runouts of start zones. Persistent slab avalanches can be triggered remotely, so your best bet is to avoid traveling on, above, or below 30º slopes.

    (2/5/2024)

    Large persistent slab avalanche off of McGee, observed 02/05 in the am. 

    Photo: Samantha Rubin

Avalanche Discussion

After a few days of high pressure, and intense wind events, we are working with lots of different snow surfaces. We have observed crusts, large amounts of soft snow available for transport by our strong Sierra winds, surface hoar and near surface faceting. Due to variability, we have a decent level of uncertainty regarding how well the new snow and wind deposits have bonded to the surfaces beneath. 

The variability in snow surfaces matches the variability in snowpack structure throughout the region. We are starting to see healing of the depth hoar and the 1/02 facets in certain areas, and we are still seeing reactive depth hoar up to 10 mm in others. We are seeing new layers of facets developing between melt freeze crusts in areas with a shallower snowpack, and we will be monitoring this closely. The new load from last night, and the incoming load this weekend, will be a good gauge to help us better understand where we are at regarding our weak layers at the base of our snowpack. In areas where the snowpack is generally shallower, it will not take much to trigger these layers.

Regions covered