Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

Tue
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 2 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Avalanche danger will increase throughout the day as more snow falls and wind speeds increase. As you start nearing 6 inches of new snow, if you identify "upside down" feeling surfaces with heavier snow over lighter snow, or wind-drifted snow, shift off steep slopes. Where you find wet snow at lower elevations, natural or human-triggered wet loose avalanches are possible so avoid steep slopes. 

Avalanche problems

  • Storm Slabs

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

    Avalanche danger will increase throughout the day as more dry snow builds up at mid and upper elevations. We could see 6 inches to a foot or more by the end of the day, depending on where you are in the zone. Increasing temperatures may aid in creating an "upside down snowpack, where heavier snow sits on top of lighter snow, which is a great recipe for storm slab avalanches.

    Wind speeds will also increase throughout the day, and areas where wind drifts snow into heavier slabs are also where it is likely that you could trigger an avalanche. As you travel, feel for heavy snow beneath you, in particular, note if you are breaking through to softer snow beneath. Search for clues like long, shooting cracks. Actively blowing snow will show you where new wind slabs are building, and clue you in on where to avoid. 

    If new snow deposits start approaching 6 inches in depth, and if you notice any upside down snow characteristics from wind or increasing temperatures, it's time to start avoiding slopes steeper than 35°. If any natural avalanche activity occurs take a step further back and avoid travel beneath steep slopes as well. Be aware that conditions will likely change throughout the day, and slopes you traveled on earlier in the day may become unstable as more snow builds up on them. 

    Example photo: As the day progresses you may be able to start triggering more or large avalanches, like this human-triggered one on a steep rollover in the Baker backcountry. 

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    In the spring it's really hard to tell exactly how wet loose avalanche activity will play out on a daily basis. More activity happened than expected on Sunday, which you can read about in THIS observation. One of our forecasters was out at Snoqualmie Pass on Monday and shared some great information about wet loose avalanche activity, which applies to all zones, and you can check out in his video HERE. One of our forecasters was out at Snoqualmie Pass on Monday and shared some great information about wet loose avalanche activity, which applies to all zones, and you can check out his video HERE.

    Lately we've been getting "greenhousing" when clouds trap heat in and moistening happens on all aspects. A lot of our previously low-density dry snow was affected by this at mid and lower elevations, and the snow ran easily on the underlying crust, around 6 inches below the snow surface. This may happen on Monday, but as previously mentioned, it's hard to nail this problem so it may or may not be as much of an issue on Monday. 

    Avalanches could start small but then suprise you by spanning wide and picking up a lot of mass as they run. First thing in the morning it might not happen but as it gets warmer activity may start. You could trigger one if you're out on a steep slope, especially if there aren't any tracks on it and surfaces are smooth. They may also run naturally. Naturals are more likely to happen in areas with rocks nearby or if trees drip or deposit snow on the surface, but it could be anywhere steep depending on the conditions. If you notice any new activity, or if temperatures are getting warmer and snow getting wetter, it's time to avoid steep slopes- but also traveling in areas beneath steep slopes as well, as natural avalanches could run down and hit you. 

Avalanche Discussion

Spring conditions tend to be a little tricky to forecast. Whether it's listed as a problem or not, always have wet loose avalanche activity on your radar, and keep in mind that these conditions may change throughout the day. Other springtime hazards to continuously remain alert around are glide cracks and cornices, as this isn't a good time to travel beneath them. Although unlikely, one could release at any moment and maybe you'll be the lucky one who is underneath when it happens. 

Your avalanche, snowpack, or weather observations are extremely valuable to the avalanche community. Help create a more accurate forecast by submitting your observations HERE. 

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