Avalanche forecast

West Slopes Central

Northwest Avalanche Center
View on map

Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

There's still a chance you could trigger an avalanche in a wind-loaded pocket of snow on Sunday. Focus on snow beneath and around you, and if you notice thicker, heavier wind-drifted deposits or any obvious clues like long, shooting cracks or recent avalanches, avoid nearby steep slopes. Most of the frigid temperatures are behind us, but don't let your guard down yet- prepare for cold weather travel with extra layers and prepare yourself for the unlikely possibility of getting stuck in the backcountry. 

Avalanche problems

  • Wind Slabs

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

    Strong winds subsided in many locations in the last day or two, but near mountain passes and further east, there may be more recent wind distribution of snow. Locations with newer slab development could have higher avalanche danger. However, places with less recent wind may have more stubborn and less reactive snow. There may be wind-sheltered areas where low-density powder exists, and avalanches are less likely to occur. 

    It's up to you to investigate wind slabs in the area you travel. Red flags, or bullseye clues, such as long shooting cracks from your steps or sled skis are indicators of a weak snowpack. If you see recent signs of avalanches, where crowns have not yet filled in, that's an indicator to avoid steep slopes. If it's still windy where you are, and you're watching the wind actively shifting snow, steer around steep patches of newly deposited snow. 

    Hand shears and small wind-loaded test slopes may give you a sense of slab reactivity. Remain alert if you head into more aggressive terrain, as initially you may find stable snow but a slight shift around a feature might transition you into a wind-loaded pocket you might trigger an avalanche in. When in doubt, avoid wind-loaded slopes greater than 35°.

    Example photo: Small wind slabs I triggered last year during a period of active wind loading in the Mountain Loop Highway. This is similar to what you might see on Sunday. 

    Photo: Irene Henninger

Avalanche Discussion

Neighboring zones reported human-triggered wind slab avalanches on Friday and Saturday. If you're traveling near another zone, have a read through that forecast as well, as information in the West Central zone is limited right now. I traveled into the west side of the Highway 2 corridor on Friday. Temperatures were frigid, it was calm, and I made it up to a whopping 3000ft. There was about 3 feet of snow at that elevation, and I found a generally right-side-up snowpack that was stable. There were 2 notable layers- graupel about one foot deep and a thin crust about a foot below that. I saw signs of old avalanches, mainly near ridgelines from about 4500-5500ft. They likely occurred last Saturday and were well filled in. I didn't see any recent avalanches, but I did see wind blowing snow at a ridgeline at 5500ft. 

Although wind slabs are the type of avalanche you're most likely to encounter, there is a tiny chance that you trigger a very large avalanche on a deeply buried layer of weak snow, or facets. A few avalanches have likely occurred on this layer in nearby zones, mostly at ski areas with explosives use and some that failed naturally during intense snow a week ago.  The weakness is most likely to exist at upper elevations and sits just above the 12/30 crust. An avalanche, if it occurs, would probably fail 3-5ft deep, something that's fairly unlikely for a human to trigger unless you find a thin spot where the weak layer, just above that obvious crust, is less than 3ft from the surface. More weight, such as a snowmobile, might be the perfect ingredient for triggering one of these very large avalanches. This may happen on a wind-loaded slope, or it's more likely you could trigger one of these avalanches in an area stripped of new snow, hence shallower. 

With the large transition to winter we've seen in the last 10 days, make sure to approach big slopes carefully. Test smaller slopes first, and have an understanding of the snowpack structure and any concerning weak layers and recent avalanche activity before approaching more committing, complex terrain. If cold temperatures persist where you're traveling, be sure to prepare for them with extra layers, and emergency heat sources in case you get stuck in the backcountry. 

Regions covered