Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Be prepared for frigid temperatures and deep snow if you head into the mountains on Tuesday. The snowpack will need some time to adjust to the recent load, so stick to conservative terrain as you gather information. Avalanches should be largest in wind-loaded terrain and easier to trigger on convex slopes, near rocky features, or on slopes over 35 degrees.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    The winds could pick up just enough that you could be dealing with some freshly built Wind Slabs on Tuesday. With snow this light, it doesn’t take much wind to transport the snow. Fresh slabs should be shallow and easier to identify by looking for textured snow surfaces or actively blowing snow. You could find that some older and possibly thicker Wind Slabs are lingering from the recent storm. Older slabs may be a bit more difficult to identify, so look for large drifts or freshly built cornices as indicators as to which slopes may be wind-loaded. If you feel stiffer or hollow-sounding snow under a few inches of light snow, that could be an indication that you are traveling on wind-loaded terrain. Although older slabs could be more difficult to trigger, if you do, the resulting avalanche will probably be large enough to bury or kill you. Take extra time to evaluate terrain features where Wind Slabs like to form such as at the base of cliffs, sides of gullies, convex rollovers, or in rocky chutes.

    (12/27/2021)

    Newly built cornices may be sensitive. If they fail, they could trigger slides on the slopes below like this one did near Crystal Mountain on 12/27.

    Photo: Shane Robinson

  • Storm Slabs

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

    In the simplest of terms, the sheer volume of snow accumulated over the past few days could be hazardous. We continue to receive reports of shallow and isolated soft slabs, which is why we are categorizing these new snow problems as Storm Slabs. Depending on where you are recreating, Dry Loose avalanches could also be a fit to capture the hazard presented by the recent storm snow. The management of these two issues should remain largely the same, regardless of your categorization preference. You can look at the upper snowpack to see if you are dealing with slabs or loose snow by using upslope tests to look for cracking, or quick hand pits and test slopes to look for failing blocks of snow. These signs would all point toward slab avalanches compared to loose avalanches. No matter which problem you are dealing with, be suspect of slopes over 35 degrees where loose snow could knock you off your feet.

    (12/19/2021)

    Using simple hand pits while you travel is a quick way to gain some information about slab potential and the depth of potential weak layers in the upper snowpack. 

    Photo: Dallas Glass

Avalanche Discussion

Around the West South, a generally right side up and well-bonded snowpack exists. That does not mean that there are no storm instabilities that still need to settle out or that avalanches are not possible. We have received up to 4 feet of snow in some areas in the zone in the last 5 days and all that snow needs some time to heal. The cold temperatures will slow the healing process of the snowpack, so be sure to take the time to do your homework before stepping into consequential terrain. On Monday, NWAC forecasters at Paradise found the Solstice Crust almost 4 feet (120cm) below the surface and plenty of evidence of wind transport. We expect any potential avalanche activity to occur above the Solstice Crust.  Professionals in the Crystal Mountain area reported sensitive cornices which could be a trigger for larger avalanches on the right slope.

Dress warmly and be sure to keep your partner in sight. The snow is still deep and soft, which creates a hazard, particularly near treewells. With some uncertainty in the weather forecast, don't be surprised if you see some flakes falling from the sky in some areas of the zone.

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