Avalanche forecast

East Slopes Central

Northwest Avalanche Center
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Avalanche danger

Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

A storm favoring the east slopes of the Cascades will bring new snow, strong winds, and dangerous avalanche conditions. Stiff slabs of wind drifted snow will form even at lower elevations. Keep your slope angles low, and select simple, conservative terrain on Friday. 

Avalanche problems

  • Wind Slabs

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

    Thursday night may bring a healthy refresh of snow to the east slopes of the Cascades. Strong ridgeline winds and increasing temperatures on Friday will accompany this new snow. Areas further east in the zone will likely see precipitation taper off on Friday with a continuation of strong winds. Expect to find wind slabs on lee slopes near ridgelines, on convex features mid-slope, and potentially located lower in the terrain than usual. New snow and wind slabs will rest on the Christmas Crust or a dusting of snow on the crust in some locations. We are still unsure how well this snow will bond to these surfaces. Areas closer to the Cascade Crest may see significantly more precipitation lingering into the day on Friday with warming temperatures. You may find sensitive storm slabs in these areas, even in wind sheltered terrain. Friday will be a blustery, wet, and stormy day. On days like these, it is best to stick to low angle and sheltered terrain. Let the winds die down, and the snowpack adjust to the new load before committing to steep slopes. Look for textured surfaces and cornice formations to point towards wind loaded terrain. Watch for signs of unstable snow that indicate avalanches are likely, such as recent avalanches or shooting cracks.

    (12/9/2022)

    Wind loaded slopes will often exist directly under freshly formed cornices like this. 

    Photo: Mitchell Barton

Avalanche Discussion

These new snow accumulations will be the first significant snow depths on the Christmas Crust in most of the East Central zone. In most locations, snow has bonded well to the crust. However, observers in the Icicle Creek area found just a dusting of snow over this breakable freezing rain crust. We are uncertain how this setup will react to the new snow, particularly in wind-loaded terrain. Keep your senses tuned into the snow and use quick hand pits to monitor this new snow interface as you travel. If you find the new snow slide easily in hand pits or small, steep test slopes produce mini avalanches, storm slabs in sheltered terrain are also likely.  

Warming temperatures may bring the possibility of rain and small wet loose avalanches to lower elevation trailheads. Sinking deeply into wet, saturated snow and rollerballs are signs that wet loose avalanches are possible. 

On Tuesday near Salmon La Sac, I found significant dry snow below the crust and a well-preserved layer of buried surface hoar in the snowpack. This persistent weak layer showed the potential for initiation and propagation in snowpack tests. Triggering this layer is unlikely because it is below the very thick freezing rain Christmas crust. However, there may be isolated pockets of terrain where a large trigger, such as a snowmobile, could initiate an avalanche on this layer. Therefore, it's worth digging down to look for this thin grey line of feathery surface hoar in the snowpack before committing to steep terrain in sheltered gullies or near rocks and cliffs. 

If you take advantage of some time off work and get out into the mountains, help us out by sending in an observation!

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