Avalanche forecast

Avalanche forecast

Payette Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Triggering a persistent slab avalanche on older, buried weak layers remains possible today. You are most likely to encounter this problem on NE-facing slopes between 7000-7500 feet, especially in the West Mountain zone. Recent W/NW winds have been drifting soft snow into dense slabs on east-facing aspects above 7000 feet.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2

    Monday, we observed several snowmobile-triggered avalanches near Council Mountain (read observation here). These avalanches ranged in size, but most were large enough to bury, injure, or kill a person. Common characteristics that we found were:

    • Avalanches failed on a layer of buried surface hoar from January that ranged in depth from 40 cm (16") to 110 cm (3.5 ft.)
    • These avalanches were on NE-facing slopes between 7200-7400 feet
    • These avalanches were in pockets of wind-sheltered terrain(pictured at right) that had been loaded by Sunday's storm 

    Yesterday (Wednesday), we were in the northeast corner of our advisory area in the Lick Creek zone. We observed a stable, right-side up snowpack. We did not observe evidence of any avalanche activity on buried weak layers. We did not observe propagation in ECTs. Professionals who had been skiing in the zone since Sunday's storm reiterated these findings.

    Buried weak layers, particularly surface hoar, are spotty and can be difficult to find. We know the possibility of triggering an avalanche on buried weak layers from January are more likely in the West Mountain/Council Mountain zone, especially in terrain features described above. I would avoid these suspected terrain features, especially in the southwest part of the advisory area.

    (2/6/2023)

    Avalanches such as these are possible in pockets that were protected just enough from the wind to preserve older weak layers 

    Photo: Studley

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Yesterday (Wednesday), winds shifted out of the W/NW and began drifting soft snow on the surface onto eastern aspects (photo to the right) . With all of the recent snow in the past five days, there is a lot of snow available for transport.  Today, winds will shift yet again to the south/southwest. All of this wind-shifting adds up to a level of uncertainty with where exactly wind slabs could be lurking. You're most likely to encounter a wind slab on slopes above 7000 feet, particularly on east-facing aspects. Due to the uncertainty and erratic winds, all wind-exposed slopes should be carefully evaluated for the presence of wind slabs.

    Pay attention to clues like shooting cracks from your skis or machine. If you feel a dense or hollow feeling in wind-exposed terrain, you've found evidence of a wind slab. Find aspects that are not presenting these clues to avoid wind slab avalanches.

    (2/8/2023)

    W/NW winds were filling in the skin track within an hour's time. Wednesday (02/08) in the Lick Creek zone.

    Photo: Studley

Avalanche Discussion

Today's avalanche forecast is sponsored by Brundage Mountain Resort. Thanks for supporting the Payette Avalanche Center.

The storm from Sunday into Monday brought 12-18 inches of snow to the mountains with southwest winds. Monday into Tuesday wind slabs were present in terrain above 7000 feet, especially on N, NE, and E aspects. Monday we observed several natural wind slab avalanches near Council Mountain. These were around 8000 feet, just under ridgelines, and mostly confined to NE aspects. We also observed several larger avalanches on persistent weak layers (mentioned above).Tuesday night, another quick-hitting storm brought 2-4 inches of snow and more southwest winds. Wednesday, W/NW winds were drifting and blowing snow on eastern aspects. Shallow wind slabs were beginning to build yesterday afternoon and dry loose snow (sluff) was moving in terrain steeper than 35 degrees.

A ridge of high pressure will bring several days of dry weather to the region. With clear skies, warmer temperatures and solar radiation will begin to take effect today. You can expect to see new snow shedding off trees, rocks, and cliffs, especially in terrain over 35 degrees.