Avalanche forecast

East Slopes North

Northwest Avalanche Center
View on map

Avalanche danger

Sun
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
Open full map
Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Strong wind will continue to load upper elevation slopes, creating very dangerous avalanche conditions. A complicated and variable snowpack may be nearing a tipping point, and need only the weight of a person to initiate a wide and surprising avalanche. Saturday is a good day to stay away from steep slopes at all elevations, as you may trigger avalanches from a distance. Conditions will become more dangerous Saturday evening into Sunday as a major storm makes landfall.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2–3

    There is lots of variability in the snowpack, and we don't have a good handle on it, especially while we are in the midst of a storm cycle such as this one. In any case, numerous reports of loud whumphing at all elevation bands tell us that we may be reaching a tipping point. Persistent slabs dominate the way we travel, and plan to travel in the backcountry because all slopes steeper than 30 degrees are suspect. Look for a thin layer of weak snow above or below a crust roughly 16"-30" down from the surface. There may be a layer of buried surface hoar a few inches above this crust as well. 

    Another storm overnight Friday with strong wind through the day on Saturday will only add to the stress on these layers. By Saturday these avalanches will be nothing to mess around with.  If you travel to mid and upper elevations, listen closely for whumphing, and look for fracturing of large sections of snow. These are direct signs that the snowpack is unstable. In this case stay well away from any steep open slope. With lots of wind drifting expected to occur, any shallow wind slab that you initiate near the surface could step down to the crust, and become a large and destructive avalanche. 

    (12/18/2020) Example of a widely propagating persistent slab that surprised experienced backcountry travelers in the Stevens Pass zone. The slide was triggered from below.

Avalanche Discussion

Another solid round of snow is expected to fall for the mountains of the Northeast Cascades. The active pattern continues, and the snowpack is getting deeper. These storms have been incrementally loading potential weak structure surrounding a crust from December 9th. Slides have been triggered and run on this crust in surrounding zones such as near Mt Baker and east of Stevens Pass. Below about 5,000ft and east of Washington Pass, this crust presents as a translucent freezing rain crust. Above and west of there, the 12/9 presents as more of a thicker and rough melt freeze crust. 

We expect very dangerous conditions to continue into the weekend, with the potential for a natural avalanche cycle Saturday night into Sunday.

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources. Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

Regions covered