Avalanche forecast

East Slopes Central

Northwest Avalanche Center
View on map

Avalanche danger

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Out of date — this forecast expired 4 years ago.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

Highlights

The danger is a tricky Moderate and its not time to tee off yet. Near and above treeline is where you'll find the largest and most overlapping avalanche problems; Beware of persistent slabs, wind slabs, and loose slides. Remember, you can always default to lower angled slopes away from large, steep and wind loaded features for some great powder conditions. 

Avalanche problems

  • Wind Slabs

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

    Recently formed wind slabs may remain easy to trigger in certain areas. Check to see how the snow reacts on small test slopes. Slabs could break deeper or widely on recently buried weak layers such as a surface hoar layer from 1/17 or a crust from MLK day. Look for punchier deeper drifts, cornices, and textured snow surfaces to identify likely slabs. Steer around steeper slopes if you find shooting cracks, or thick slabs in large terrain features where getting caught in a slide could be less than ideal. Consider the persistent slab problem described below, and the chances for slabs to step down and become much larger and destructive.

    Loose slides could run also far and fast on steep slopes. Check to see if snow entrains, or how it reacts before jumping into consequential terrain.

    Example wind slab from the 16th. Slides could be deeper and wider on Thursday.

  • Persistent Slabs

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

    On Thursday, the third skier on a slope triggered a large and surprising slab 1-2ft deep on a NE aspect at 6,200ft in the eastern part of the Stevens Pass zone. It ran on large surface hoar on firm bed surface, triggered from the shallower area. So, contrary to popular belief, we still have a persistent slab problem. The slide even broke through the MLK crust which was about 5mm thick in this location. 

    It's time to rethink how you travel with these dangerous avalanches in mind. You might be most likely to trigger one on N-E aspects above 6,000ft, in areas where the MLK crust is fairly thin. Treat steep slopes that fits this description with a large amount of skepticism, identify and avoid them.  You could dig down and look for feathery surface hoar about 2ft down. Unfortunatley, distribution is variable throughout like aspects and elevations, so even if you don't find it in one place, that doesn't mean its not hiding out in another. 

    (1/19/2023)

    Large avalanche on a layer of buried surface hoar. NE at 6,200ft on Jim Hill. The crown was 1-2ft deep.

    Photo: Ryan Minton

Avalanche Discussion

Friday should bring sunshine, so keep that in mind and expect to see it's influence on snow surfaces on southerly aspects. The recent storm brought 4-8" of new snow in the zone, and locally strong ridgetop winds were observed drifting snow at ridgetop on Thursday. Mission Ridge patrol reported triggering a large slab that ran on the MLK crust, with a crown 6" to 24" deep and over 50ft wide. Other wind slabs were triggered but smaller and didn't break down to the crust. Wind slabs were reactive on the crust on Wednesday as well, and an observer reported triggering a 6" deep one that ran on the MLK crust that day near Mission Ridge. Some weak snow such as this could make for surprising and wide avalanches in certain places. Small cornices were also touchy off ridgelines. The riding conditions have improved substantially, though the crust could still make for slick or slippery conditions on steep slopes, especially below treeline. 

A subsantial warm and wet storm from Thursday through the weekend resulted in a widespread natural avalanche cycle with at least a few D3 wet avalanches, dozens of large wet avalanches, and many smaller storm/wind slabs. Prior to this last storm, there were many reports of folks triggering avalanches on an older layer of buried surface hoar (1/4) and subtle crusts. These persistent weak layers still warrant caution for the time being.

Regions covered