Avalanche forecast

West Slopes North

Northwest Avalanche Center
View on map

Avalanche danger

Thu
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
Open full map
Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Rain finally transitioned to snow in the mountains, and we may see around a foot at higher elevations, bringing a change to our main avalanche concerns with it. We're not quite sure how well the new snow will stick to the old snow layer, so be sure to evaluate the snow as you travel and pay attention to obvious indicators like recent avalanches as hints to stay off steep slopes. Steer around steep, wind-loaded pockets of snow, as wind will have redistributed snow into drifts and these drifts are where you're most likely to trigger an avalanche. 

Avalanche problems

  • Wind Slabs

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

    There are a lot of different ways that this new snow avalanche problem could play out, so it's important to start the day conservatively and assess the snow as you travel. The most likely avalanche problem that you'll encounter is wind slabs, as strong winds will quickly shift new snow into reactive drifts overnight and into the day. These drifts are expected to be larger and more reactive the higher you go. Depending on how much snow ends up falling at higher elevations, drifts could be two or more feet deep.  Smaller wind slabs at lower elevations might be the only spot where snow is deep enough to produce an avalanche that could take you for a ride.

    Feel for changes in the snow as you travel. If snow quickly gets deeper, or becomes firmer you've probably stumbled across a wind drift. You may also spot thicker, pillowed-looking snow deposits. Active wind loading could still be happening, as winds will decrease but continue throughout the day. Search for these drifted locations around rocky outcroppings, just below ridgelines, on steep rollovers, and in gullies.  Avoid wind-loaded pockets on terrain greater than 35 degrees during your outing. 

    (12/3/2022)

    You might encounter wind slabs in gullies and around rocky outcroppings as wind shifts the new snow as it falls and during the day. Avoid steep areas where you find wind slabs. 

    Photo: Public Observation

  • Glide Cracks

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

    Rain may have finally slowed but glide avalanches tend to remain a problem for a while afterwards, especially as we recover from the whopping 14" of rain that was recorded at Heather Meadows in the last 4 days.  A glide avalanche may seem unexpected now that there will be some fresh snow on top, but remain alert to this problem. The rain will continue to percolate down through the snowpack for at least the next few days, continuing to lubricate underlying smooth surfaces like rocks and low vegetation and loosening deeper snow bonds. It's tough to tell whether a glide crack will release in an avalanche soon after a glide crack formed, or not at all, and this is a good reason to exercise extra caution around them.

    If you spot any glide cracks near the top or middle of a slope, steer around the slope beneath these features. Avoid or travel quickly across the flats beneath glide cracks. Don't get lulled into a false sense of security by the pleasant new snow, an overhead glide crack is a looming problem that should dictate whether you're on a slope or not. They're too unpredictable to gamble with traveling beneath them right now. 

    (1/14/2022)

    A photo from last year with rain rills and glide cracks on Table Mtn. It probably looked pretty similar up there this week, before the new snow sneakily hides the textured snow surface. 

    Photo: Lee Lazzara

Avalanche Discussion

We have no reprieve as we quickly transition from rain to finish up the most recent storm with snow. We suspect that the wet snow surface and initial moist snow falling will hopefully mean that the interface between the new and old snow layer will be strong, and the continuing cooling temperatures will lead to a right side up, more stable new snow layer. We're not certain about this however, and the new snow may end up sliding easily on or near the soggy interface. If this is the case, any areas where the new layer is nearing 6 inches deep could slide in steep areas. Using small test slopes and pushing snow down to see if it slides easily on the old snow layer would be the best indicator of whether this might be a concern for your day. If it is, avoid steep slopes where enough new snow exists to cause this problem. 

Conditions will be out of the ordinary on Wednesday. At lower elevations where the snowpack is only a few feet deep you can expect to sink to the ground on your feet. Even as you gain elevation you'll still probably sink pretty far into the snowpack. Creeks will be raging, and unsuspecting holes will be present in the snow. The new snow could hide all sorts of bare patches, holes and other hazards. The new layer will likely insulate the "warmer" snow beneath it, keeping the wet layer soft at least for a few days. Eventually the old surface should firm up a bit. As temperatures cool, water drains from the snowpack, and snowfall intensity backs off during the day, we may finally be seeing a downward trend in avalanche activity after a wild and busy period in the last week. 

Regions covered