Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

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

Although our layered snowpack is starting to heal, avalanche conditions remain dangerous. Slabs could fail within the new storm snow or break down to recently formed interfaces. Avoid large, open, and poorly supported slopes steeper than 35 degrees.

Avalanche problems

  • Storm Slabs

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

    New instabilities will form over the next 24 hours with heavy snowfall at times. The new snow will be particularly reactive following heavy snowfall, periods of wind, or if a distinct graupel layer happens to develop. At middle and upper elevations, there's plenty of snow for these avalanches to entrain and grow large. At lower elevations, you may find the underlying snow to be firmer due to mild temperatures on Wednesday, limiting the avalanche size. Avoid all steep or poorly supported open slopes until you evaluate a representative test slope. Look for propagation on skin track tests or planes of weakness in hand/shovel shear tests. If you encounter shooting cracks, this would initiate an avalanche on a steep slope, so dial back your terrain selection. Also evaluate Wednesday's warming layer. If it's firm and supportable at your elevation, it may limit the size of avalanche activity, but this may not be true as you ascend higher in the terrain.

    We're nearing the latter stages of a multi-day storm cycle, and given the recent reports of multiple reactive interfaces, these may wake if you trigger a smaller avalanche within the new snow or perhaps on a poorly supported convexity. It remains risky to engage with large and committing terrain features on Thursday.

    (3/11/2025) A long shooting crack such as this should keep you off steep, open slopes.

    Photo: Oliver Kramer

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    At this point it's difficult to know whether a thin layer of surface hoar remains an issue, but with an ongoing storm cycle continuing to stress the layer, it's best to keep it on your radar. We received a number of reports of human-triggered persistent-type avalanches in Canyon Creek on Monday, but no activity on that layer since. Surface hoar that was widespread on the snow surface prior to the recent storm cycle has survived and was buried in that subzone. Other subzones like the Baker BC  and Schriebers/Mt. Baker NRA saw plenty of traffic with none like these reported as of Monday evening. Some propagated widely or were triggered from the side or below. Although the initial round of reactivity wasn't especially deep, perhaps 1-2 ft below the snow surface, we expect potential crowns to be 3  ft or deeper by Thursday. This would produce large and difficult-to-survive avalanches on steep, open slopes. Be prepared to check the 3/8 interface, likely a few inches above a hard crust. In areas that might have this problem, natural or human-triggered storm slabs could step down to this layer. In Canyon Creek or less explored areas, it would be wise to keep some extra space between yourself and steep NW-N-NE facing slopes at middle and upper elevations.

     

    (3/10/2025)

    A snowmobile triggered avalanche on a northerly, upper elevation slope in Canyon Creek. Note the crown wrapping around the convex feature. This is suspected as having failed in a layer of surface hoar buried on Saturday.

    (SS-D1.5-AM-I)

     

Avalanche Discussion

Around 10-12" of new snow fell in the Baker Backcountry over the last 24 hours, redistributed by moderate S winds. This produced widespread wind slab reactivity for Mt Baker Pro Patrol in exposed terrain. The top 6-8" of snow consolidated into a reactive storm slab as temperatures warmed and we had a report of a size 1.5 human-triggered slab avalanche on that layer. A resistance change along with the 3/9 melt-freeze crust were also producing sudden results in snowpack tests. The March 9th crust is down around 2 ft. The March 4th crust is down around 40". There are no layers of concern below this crust.

Mt Baker Pro Patrol and Baker BC travelers triggered another round of mostly shallow 6-8" slab avalanches on Wednesday.  Here's a report of a human-triggered slab avalanche along with mention of some fresh natural activity on Shuksan Arm. Moderate to strong winds Tuesday night and Wednesday contributed to widespread slab reactivity that focused on new snow that built up since the snow picked up around 6 AM.  Temperatures warmed mid-day, producing "hot pow" in the mid-day and afternoon hours, but it remained barely snowed at White Salmon base. 

Wednesday's reactivity comes on the heels of even wider slab propagation on Tuesday.  Most of the activity occurred on an interface buried 3/10 involving some partially faceted snow. Other avalanches involved only the storm snow that fell heavily on Tuesday morning. In some cases, the slabs ran down to the 3/9 interface. Most of the activity occurred on wind-loaded slopes. Some were natural, and many were human triggered, including from below.

We're well into a multi-day avalanche cycle in the West North. Several very large naturals likely released overnight Sunday and were observed to have run from high on Shuksan Arm and on Shuksan proper, down to the valley bottom. These likely involved wet snow.

 

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