Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

Avoid steep slopes with fresh, wind-drifted snow, as we're expecting about 6" Thursday night and another few inches during the day, over the snow we received Thursday. The new storm snow rests on a variety of surfaces ranging from crusts that are bumpy or smooth, and north-facing upper elevations hold an irregular weak layer that the new snow will be resting on.  It may be difficult to tell where pockets of more reactive snow will be, so evaluate conditions as you travel, assess the new snow/old snow bond, and step back to lower elevation terrain if you have any doubt.

Avalanche problems

  • Wind Slabs

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

    The first week of spring and nice weather doesn't mean spring has fully sprung yet - it'll be cold and snowy the next few days. Don't put your winter avalanche mindset away yet.  THIS observation about snow and avalanche conditions in the Baker backcountry from Thursday was an excellent precursor to Friday, when we're expecting to find more snow and reactive conditions.  Very small pockets of wind slab reacted to a human trigger on Thursday, but with 6" or more of snow by Friday we expect the size of these avalanches to grow, possibly to a foot or more in depth and spanning larger areas as well. It is likely that a human could trigger an avalanche. We expect most avalanches to occur in wind drifted areas, but on the upper elevation northerly aspects that may harbor near surface facets on the old snow surface, even non wind-loaded pockets could avalanche as well, especially where the snow is 6" or more in depth. Most everywhere else the old snow surface is a crust, which could also be a good sliding layer.

    Now that we've got cold temperatures and low-density snow back, it's time to stay on your game and pay attention to conditions as you travel, evaluating the new snow layer and determining how easily it slides on the underlying layer. You can use small test slopes and hand pits to help you determine this if you know how to do them.  Search out wind-drifted locations by feeling for stiffer snow and visualizing textured surfaces. Identify common locations for wind loading like in gullies, around features and on steep rollovers. Use these factors to help you determine where wind slabs are and obvious areas to avoid on slopes steeper than 35° if you find the snow slides easily or you're in a wind-loaded area. If snow is more reactive than expected, or we get different wind or snow amounts than forecasted, conditions may be different than this forecast. If this is the case you can always take a step back and stick to lower-angle terrain.  

Avalanche Discussion

About a day has passed since temperatures have finally started cooling off, but this is still prime time for glide avalanches to continue running. Avoid areas where you see glide cracks, or suspect they may exist. On a non-avalanche-related note, a few days ago someone fell into a glide crack which was hidden by a snow bridge in the Baker backcountry. They made it out unscathed, but this is a spring risk while traveling in steep, mountainous terrain. Cornices remain a concern as well, so stay far back from them and think twice before traveling beneath them. 

In the last week of primarily warm, sunny weather we've seen a constant trickle of wet loose avalanches, abbreviated by the occasional larger slab avalanche or glide avalanche. Many of these wet snow problems have dissipated with the cold temperatures but not all yet. As previously alluded to, a lot of old snow surfaces will be firm, sneakily hidden by a new coating of snow. The old layer could be smooth or could be very bumpy, with old refrozen wet avalanche paths or debris piles hidden by the new snow. You'll likely find irregularities with your feet or sled, however, so travel very carefully on Friday. 

Along with spring we get unsettled weather and even a small cloud break could lead to a small round of wet loose avalanches in the new snow on the southern half of the compass. If the sun comes out keep this in mind. The low density new snow layer could also sluff naturally, or run as small dry loose avalanches, on steep slopes as well. 

 

 

 

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