Avalanche Forecast

Heavy rain, snow, and wind will combined to create dangerous avalanche conditions. You can trigger a dangerous Wet Slab avalanche at most elevations through midday. These avalanches may even run naturally. Watch for liquid water reaching buried crusts or softer layers of snow well-below the snow surface as a sign that Wet Slab avalanches could occur. Wet Slabs are dangerous because they are hard to predict, give little warning, and can be very destructive. If you see slab avalanches in areas of wet snowpack, avoid traveling in avalanche terrain. You may be able to trigger smaller Loose Wet avalanches more easily in the same types of terrain where the Wet Slab problem exists.

There's a chance that large Glide avalanches could release naturally. Use extra caution and avoid stopping near and below snow covered rock slabs where Glide avalanches could occur. With poor visibility and dangerous avalanche conditions, it's critical that you limit your exposure to large avalanche terrain from above. Many areas, such as the Alpental Valley, are exposed to complex overhead avalanche terrain that cannot be seen from below. Use maps, satellite imagery, and expert local knowledge to limit your exposure.

You may see a dramatic shift to snow at mid to upper elevations later Saturday and into Saturday night. Wind and new snow will form Wind Slabs on lee slopes near and above treeline. Visual clues such as blowing snow, fresh cornices, and cracks in the snow all indicate that you could trigger a Wind Slab avalanche. Snow falling on recently wet surfaces could result in a problem weak layer.

Vigorous stormy weather resumes Saturday. Rain has moved into higher elevations and soaking previously dry snow laid down early this week. The April 1st-2nd storm deposited a relatively even blanket of 1.5 feet of snow across the Cascades West and Passes zones and has now been soaked at most elevations. In most locations, last weekends snow fell on a firm melt-freeze crust (4/1) up to 5,500ft. This could be a problematic weak layer for Wet Slabs this weekend. Other potential layers of concern for Wet Slabs include:

-A weak layer (3/22) down 2-3 feet (60-90cm) below the snow surface. On sunny aspects, this could show up as a thin layer of firm crust.

-A series of crusts and softer snow about 3 feet below the snow surface.

-The 2/8 crust, now 5-7 feet below the surface. This was associated with the 2/13 facets. Though it's unlikely, if significant water pools on the crust, it could result in very large and dangerous Wet Slabs.

Observations

Central

NWAC avalanche forecaster Josh Hirshberg was at Stevens Pass Monday and Tuesday. Josh reported 16 to 18 inches (40-45cm) of new snow in sheltered locations. Near ridgeline, winds  transported snow, forming drifts up to 22 inches (55cm) deep. No new avalanches were observed.

NWAC avalanche forecaster Dallas Glass traveled in the Snoqualmie Pass area Tuesday. Dallas found 18-24 inches (45-60cm) of settled storm snow, generally well bonded to the old 4/1 crust. Several natural and human triggered loose dry avalanches were observed. 

South

NWAC professional observer Jeremy Allyn traveled in the Crystal backcountry Monday. Jeremy found wind transported snow above 6000 feet. The new snow was moderately bonded to the old snow surface with the bond strengthening during the day. As the sun came out, sunny aspect quickly became moist to wet and produced rollerballs.