Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

Thu
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

You can still trigger slab avalanches in steep terrain. Stick to moderately angled slopes and navigate around trigger points like convex rolls, unsupported terrain above or around cliffs, or wind loaded slopes just below ridgeline. Look out for wet avalanches if the sun makes an appearance. Give large and looming cornices plenty of space as it warms up through the week.

Avalanche problems

  • Storm Slabs

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

    Avalanche activity and stability in general varied widely Tuesday. For the most part, the new snow has set up well with lots of people enjoying the snow in steep terrain with few issues. Most of the dozen or so slab avalanches backcountry travelers triggered were: 

    1) Small and 6-12" deep  2) In terrain around or greater than 40 degrees  3) On slopes where a shallow slab developed near the surface from either warming or wind transport

    But a few slab avalanches were outside of this pattern. One was a very large, deep slab in extremely steep, unsupported terrain. It was triggered during avalanche mitigation work (photo 5 in the gallery). The other is in the attached photo for this problem. With this information, it's pretty hard to say slab avalanches Wednesday will be of a certain kind that you find in a certain place. The likelihood is lowering but the new snow still presents some danger on all aspects, wind loaded to not. 

    If you want to reduce the risk of triggering a slab then stick to moderately angled terrain with no unsupported features like convex rolls. Westerly winds could create new wind slabs as well. You might also want to avoid terrain where you observe recent or active wind loading.

    If pushing into bigger terrain the best you can do is pick slopes with no consequence in the runout. There are still some question marks out there and it might take a day or two to figure out the answers.

    (3/14/2023)

    Human triggered slab avalanche 2-3' deep along the traverse to Shuksan Arm. The bed surface was reported as a crust. Numerous people had crossed the slope in the same area before it finally released in the early afternoon. ESE at 5300'.

    Photo: Geddy Miller

Avalanche Discussion

In addition to the slab avalanche activity listed above, numerous wet loose avalanches to D2  were reported by Tuesday afternoon. They were mostly found on southerly aspects but at all elevations from down in the trees to way up in the alpine. Less sun, a bit more wind, and similar or lower temperatures are forecast for Wednesday. It's less likely we will see the same level of wet loose avalanche activity - but it doesn't take much sun this time of year to warm things up. If the sun does come back for Round #2 look for the usual signs of instability like wet, unsupportable snow surfaces, rollerballs, or small avalanches. Stay off and away from steep and sunny slopes where you observe any of the above.

Signs of avalanches that released during the peak of the storm were visible everywhere if you looked close enough. Debris piles covered with snow, filled-in crowns, and avalanche paths full of wet, frozen chunks were found throughout the zone on all aspects and at all elevations. New snow amounts range from 2-3' in many areas across the zone. The new snow is settling but steeping off your floatation resulted in a bit of wallowing in many areas. Southerly aspects should have a breakable crust topping the snow surface while shaded aspects hold cold dry snow and excellent riding conditions.

 

 

 

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