Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

We’ve already have a weak snowpack, and now it’s going to start snowing. Saturday’s storm totals probably won’t tip the scales, but they’ll start to build new slabs in wind-loaded areas. Watch for firm pillow-like drifts along exposed ridges and rocky terrain.

Avalanche problems

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2–3

    This problem is much less likely, but it’s super scary and hard to predict. Older facets exist 3-6 feet deep in the snowpack on or just above the Early February Crust (EFC). They have a track record of producing slides over the past 10 days. Sure, avalanche activity has slowed more recently, but we keep finding huge crowns in the mountain. Two were spotted Thursday, one near White Pass and one on Mt Rainier. Snowpack tests also continue to produce consistent and sudden results. 

    The likelihood may be very low, but these things will be big! You may not get any signs you need to turn around until the slope releases. The only tool we have to manage this thing is avoidance. Consider fully staying out of large avalanche paths. This will be even more important as these storms continue.

    (3/7/2024)

    A widely breaking crown on the Conrad Glacier below Gilbert Peak. [N 7500']

    Photo: Andy Harrington

  • Wind Slabs

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

    Increasing winds will start to drift the soft surface snow into new slabs. As the snow starts to fall, this will only make this process easier. Winds should shift from SE to SW during the day, this could result in shallow wind slabs on both sides of the same ridge. 

    Fortunately, these avalanches should be fairly small. However, they could trigger easily or even break above you. Keep an eye out for firm pillow-like slabs along ridges, cliffs, and rocy exposed terrain. 

    One scary potential, is these smaller avalanches could trigger the much larger deep persistent slabs. Given the combination of the two problems, put plenty of space between you and the avalanche concerns Saturday.

    (3/1/2024)

    Example: A small but wide intentionallly triggered wind slab avalanche. NNE, 6500ft. 

    Photo: Dallas Glass

Avalanche Discussion

NWAC is devastated to report the death of one of our Avalanche Forecasters, Matt Primomo. Tragically, Matt passed away in a non-avalanche accident away from work on Thursday, March 7th. Matt has been a key member of the NWAC family since 2017. His life in the mountains touched so many people. We are absolutely heartbroken. Please join us as we mourn this immense loss with Matt’s family, friends, and community.

Discussion:

The first in a series of winter storms will start to impact the West South zone on Saturday. Areas closer to Mt Rainier will see the most snow. It may take a while for the snow to start to stack up, but with the underlying deep persistent issue, the avalanche danger will be present, even first thing in the morning. 

The snowpack became very aspect-dependent over the past few days. A surface crust formed on most southerly slopes. In some places, its thick and strong, in others weak an breakable. Surface hoar and facets formed on nearly everywhere during the past few cold clear nights. It almost certainly survived in shaded terrain, but may have hung on even on some sunny slopes. If you’re out before the snow flies, pay attention to what’s on the surface. “Today’s surface is tomorrow’s weak layer.”

Below the top, several feet of well settled right-side-up powder exists. This caps the deep persistent weak layers from February (2/19, 2/14, 2/11, EFC). The EFC is the very prominent and thick crust typically 3-6 feet below the surface. 

At the lowest elevations, wet snow and rain could create a few very small wet loose slides. These tiny avalanches shouldn’t pose too much of a threat. 

Regions covered