Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 2 years ago.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

Highlights

Look for pockets of freshly wind drifted snow as you climb into more exposed terrain. Pick more conservative terrain to reduce the consequences of getting caught in a low-likelihood but dangerous slab avalanche.

A snow immersion accident resulting in a fatality occurred in backcountry terrain on Wednesday. Keep your partners in sight at all times. Stay close enough to help them if they get buried in a tree well or some other deep snow hazard

 

Avalanche problems

  • Wind Slabs

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

    Increasing alpine winds overnight have the potential to build some fresh slabs. While wind speeds aren't necessarily strong, there’s plenty of soft, light snow at the surface available for transport. Areas that don’t see a wind increase won’t have this problem. Places that see stronger winds could have it at mid-elevations as well.  Areas north of Hwy 2 and east of the Mt Loop should see the most wind overnight.

    Textured or scoured snow surfaces, cornices, and wind lips will point towards slopes holding freshly wind drifted snow. Track changes in snow stiffness and use simple tests like hand shears and slope tests to figure out if you could have a run-in with a fresh wind slab.

    (3/13/2024)

    Visual  clues help highlight where wind slabs may occur.

    Photo: Dallas Glass

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2–2.5

    The likelihood of triggering a large, widely propagating, or surprising avalanche is lessening as the snowpack adjusts to the load of recent new snow. That being said, poor snowpack structure still exists with faceted snow lurking 2-4’ below the surface. 

    If you were to trigger one of these avalanches it would be . . . 

    • Where there is less new snow over the faceted layer - possibly easier to trigger
    • On very unsupported slopes like steep convex rolls or terrain above cliffs - more stress at the slab-weak layer interface
    • In less traveled terrain where there is less information about stability
    • If you put down a big load on a slope like multiple snowmobiles or a big group of people 

    At the end of the day, it comes down to risk tolerance. Want to completely avoid triggering one? Avoid steep slopes. But most also want to get a taste of the very, very, very good snow conditions of late. The best way to stack the deck in your favor is to stick to planar terrain with no consequences in the runout below like rocks, cliffs, gullies, or other terrain traps. 

    (2/3/2021)

    Avalanches that fail at a layer of buried facets tend to propagate wider and be much harder to escape than the typical new snow slab avalanche.

Avalanche Discussion

Soft unconsolidated snow at the surface means you could see small loose snow avalanches. Stay alert to snow moving with you if descending steep terrain. Look for loose snow avalanches below cliffs, especially as the sun causes snow to shed onto slopes below.

Most areas have three feet or more of right-side-up snow over the old snow surface buried on January 30th. This snow sits directly on crust in terrain that saw strong sun and warming from January 26th through 29th. On more shaded slopes, the new-ish snow lies over a layer of faceted snow over a crust - now decomposing - that formed closer to the new year.  More faceted snow is found below crusts on all aspects. 

The snowpack set up along the west slope of the Cascades is similar but avalanche activity has played out differently depending on forecast zone. Stevens Pass has seen minimal avalanche activity while a fresh natural avalanche was reported from Snoqualmie Pass on Thursday. West North saw a flurry of natural avalanches over the weekend and also a human-triggered avalanche on Sunday that resulted in a burial (and thankfully a successful recovery) . But avalanche activity has tapered there despite plenty of folks pushing into steep terrain. 

Minimal snowpack information is available for West Central. Don't ignore obvious signs of instability like whumphing or shooting cracks, but don't think the absence of these signs means you are good to go. Send in an observation if you get out there in the coming days.

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