Avalanche forecast

West Slopes North

Northwest Avalanche Center
View on map

Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
Open full map
Out of date — this forecast expired 5 months ago. You’re viewing past conditions, not the current bulletin.

Highlights

Expect a turbulent day with stormy conditions, new snow, wind loading, rising temperatures, and rain. Stick to simple sheltered terrain with limited exposure to big slopes overhead, especially if you make it above 5000 feet.

Avalanche problems

  • Storm Slabs

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

    Heavy snowfall at upper elevations will rapidly increase the risk of triggering a slab avalanche. Mid-elevation terrain will see a change from snowfall to rain at some point in the morning, but could also have similar new snow instabilities before that happens. Strong winds mean you are more likely to trigger a slab on leeward slopes and features, but there is enough new snow falling with rising temperatures that you should look for instability regardless of aspect or exposure to wind.

    Denser snow over weaker snow below is the first sign that a storm slab problem is building. Small slope cuts and hand shears can help assess bonding, but stormy weather, poor visibility, and reactive slabs favor conservative terrain choices. Stick to lower-angle slopes. Shooting cracks and recent avalanches are obvious signs to avoid steep terrain.

    (12/8/2023)

    Hand pits are a great way to look at the recent storm snow. Look for strong over weak layers and places it fails easily. 

    Photo: Andy Harrington

  • Loose Wet

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

    The size of any wet avalanches you see will depend on how much snow accumulates before snowfall switches to rain. If there is only an inch or two, you might not see anything more than a few rollerballs. But if snow stacks up deeper before rainfall, wet avalanches could become large enough to be dangerous. Avoid travel on or directly under steep slopes where you see fresh rollerballs or where the snow is turning mushy and wet.

    Rollerballs initiating from trees and other steep, rocky areas. These are indicators that more wet avalanche activity could follow. 

Avalanche Discussion

There are a couple of contributing factors that could make new snow accumulations on Tuesday more reactive than normal. The main one is that the new snow will fall on a sharp warming trend, so wet snow falling at warmer temperatures will build a slab over drier, weaker snow below. Also, a trace to a few inches of new snow that fell over the last few days has faceted and weakened and could make for a poor bond at the old-new snow interface. Finally, all this is accumulating over a firm crust.

One of these factors is reason enough to be a bit more on guard with fresh snowfall; all three of them together mean it’s quite likely new snow slabs will be more reactive than usual. This will primarily be an issue at and above 5000 feet, but you might also find dry, unstable slabs below that elevation in the morning.

NWAC Forecasters along the west slope of the Cascades found similar conditions on Monday, namely Low danger and thick crusts. But there were still some differences. Temperatures were warmer to the south–a high of 49F at the White Chuck Tripod at 5000 feet in West Central–so snow surfaces actually softened up even on shaded slopes. On the other hand, the mercury only topped out at 38F at the same elevation in West North, and the snow surface generally stayed firm, bumpy, and unforgiving. The other big difference is the amount of new snow over the crust: little or none in West Central and Stevens Pass, compared to 2-4 inches farther north.

Regions covered