Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

Tue
Alpine
4 · High
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Uncertainty is the main topic of the day, which makes Monday a good time to travel conservatively. As you gain elevation, transition from avoiding steep terrain to avoiding all avalanche terrain where snow is deeper and dryer. Dry snow avalanche problems will shift to wet snow problems as the day progresses. 

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2–2.5

    Expect large natural and human-triggered new storm snow avalanches at mid and upper elevations Monday. Snowfall rates and temperatures will increase throughout the day, leading to a more unstable snowpack. Higher elevations that stayed cooler are where you will encounter the largest avalanches and most reactive conditions. Mid-elevation snowpacks became heavier with warmer temperatures Sunday and may not be as reactive with storm slabs. Failures could occur within or underneath the new snow layer, which may be up to 3 feet deep. Either way, this isn't a good time to test avalanche terrain. Avoid all steep slopes and lower-angle terrain beneath slopes greater than 30°. 

    (12/2/23)

    A human triggered avalanche in the 10 Minute Trees area of the Baker backcountry. NW, 4800ft. The crown was 50-100cm deep. It ran at the new/old interface, on facets. SS-ASr-R2-D2-I

    Photo: Phil Straub - Cascade Mtn Ascents 

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1.5–2.5

    Freezing levels will rise all day and at some point wet snow avalanches will become your number one problem. Wet snow avalanches will start at lower elevations, and as temperatures rise, wet snow avalanche activity will creep up in elevation. At first, you'll see loose avalanches but at some point, they may transition to wet slab avalanches. Loose avalanches are generally predictable and will probably stay less than a foot deep, but wet slabs are a completely different scary and unpredictable beast. If you're out on Monday pay attention to indicators like the snow becoming water-saturated around a foot or more deep, indicating that wet slab avalanches could start coming down.

    Timing is uncertain regarding wet loose and wet slab activity. We expect you'll see wet loose avalanches for much of the day, elevation-dependent. As wet loose activity reaches upper elevations that were previously cold and dry you can expect to see extensive natural activity at that elevation band. This will probably start occurring in the afternoon.  Slab avalanches may hold off until overnight, with a natural cycle that will probably happen as temperature and precipitation rates peak. Due to the uncertainty, remain extra cautious today and avoid all avalanche terrain, especially if you make your way to higher elevations. 

    Example photo: Wet loose avalanche activity from a rain event in 2019.

Avalanche Discussion

Many backcountry users were out on Saturday. Two reported triggering avalanches and most people experienced whumphing, obvious signs of an unstable snowpack. A lull in overnight precipitation was followed by rising freezing levels and just over half an inch of water on Sunday. The few folks who were out Sunday reported a stubborn snowpack at mid-elevations. We'll see another lull in precipitation Sunday night before extreme warming up to 8000ft with the atmospheric river Monday night. We're not quite sure how the snowpack will react when over an inch of water and the rising temperatures come into play Monday. This is a good time to stick to mellow slopes away from large avalanche paths. 

Upper elevations may have 3 or more feet of snow from the storm that began Thursday. This is sitting over a base of 2-3 feet. The base is a mix of wind-packed snow, melt-freeze crust on the south, and weak, faceted forms on some northerly aspects. Snowline before this storm was in the 3-4000ft range. So far, most of the reported avalanche activity has occurred at the new/old interface where facets exist on north-facing terrain. This warm, wet event occurring over the next 48 hours will hopefully impact the weak snow on northerly aspects. Glide avalanches could already become active in areas with smooth rock slabs or low shrub slopes. Lower elevations don't have as much snow and have already been impacted by at least a day of rain, meaning they're probably less likely to avalanche and smaller ones if they do slide. 

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