Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

The combination of multiple nights with poor refreezes, mild temperatures, and filtered sunshine leads to elevated uncertainty on Saturday. Ease into the terrain, using test slopes to evaluate before committing to steeper open slopes. If you see signs of fresh avalanches entraining significant snow, limit your exposure to slopes steeper than 35 degrees.

Avalanche problems

  • Loose Wet

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

    Unseasonably warm weather continues on Saturday following a 3rd night with a poor overnight refreeze. This setup could play out one of two ways: (1) We see very little avalanche activity despite the sloppy snow surface conditions. Or (2) we start to see some gouging avalanches.

    How to manage the uncertainty associated with this problem right now? You'll want to limit your exposure to large, steep, and open slopes. If you choose to engage with that terrain, evaluate test slopes first. You can dig down to the AR crust (buried 2/22) just over a foot beneath the snow surface and check for shear quality. Also, try stomping on a small steep slope to see if you can get the surface snow to move. If you find that the snow has a propensity to shear or entrain, then choose a different aspect and repeat the process.

    Any signs of fresh avalanches entraining significant surface snow should give you pause to stop, re-evaluate, and consider avoiding exposure to all slopes steeper than 35. These avalanches can be the canary in the coal mine. 

    Example:  Wet loose avalanche activity can be particularly problematic where it involves terrain traps such as this.

    Photo: Kaitlin

Avalanche Discussion

Preliminary Report: On Friday, February 28, three snowmobilers were riding near Harts Pass in the East North zone when they triggered a large slab avalanche. Two riders were caught and carried. One rider was fully buried and killed. The other was partially buried and injured. NWAC is working with local avalanche professionals to conduct an investigation. Our deepest condolences to the family, friends, and community. (NE, 6,800ft HS-AM-D2.5-R4-O)

The unusually warm late February / early March weather continues. ONP Rangers at Hurricane Ridge didn't report much in the way of rollerballs or fresh wet loose avalanche activity. However, reports of gouging avalanches have started emerging from the Mt Baker area and other portions of the northern Cascades as the snowpacks adjust to the unseasonably mild temperatures. Could the Hurricane Ridge area wake up in a similar way on Saturday? It's certainly possible. And you should plan a tour that gives you easy options to travel back safely if the mountains do start waking up.

The most recent detailed report from ONP Rangers in the Hurricane Ridge area comes from Thursday. They observed heavy, warm, and sticky snow best described by the highly technical term "schmoo."  A storm system Monday night into Tuesday deposited an average of 14" of snow at middle elevations. The system arrived with strong winds, creating thicker deposits on some N and E aspects, while ridges are often scoured to grass, dirt, or rocks. The surface snow moistened on all but upper elevation shaded aspects thanks to above-freezing temperatures and partial sunshine Wednesday and Thursday. On N aspects, the post-storm warmup has created 6" of denser (upside down) snow that made riding quality poor and trailbreaking more difficult. On W-S-E aspects, the upper snowpack is right side up. The snow everywhere is fairly glued in and wasn't responsive to the rider trigger. Although there was plenty of rollerball activity, it was all very superficial. 

Below the new storm snow, there is a 2/23 rain crust (that is gradually refreezing), a few inches of dense snow below that, and then the 2/22 Atmospheric River (AR) crust. We're continuing to monitor the AR crust, which was reactive to shovel shear tests on Thursday. This reactivity remains a small possibility until the 2/23 crust freezes fully.

An avalanche on a NW aspect on Steeple Rock (photo in the gallery) may have run on the 2/22 interface. The vertical and sharp nature of the flanks suggests that the slab involved moist snow, potentially from warming after the storm. This slab activity could have run down to the 2/22 interface. Three avalanches in N Bowl (size 1.5) show storm-related and potentially wet slab activity associated with Monday's storm. The crowns are filled in to varying degrees, suggesting that they occurred at different phases of the storm cycle.

Share your observations with the community and NWAC. Even if you didn't see an avalanche or a snowpack test, your information is incredibly valuable.  Every afternoon, 4-5 NWAC forecasters from around the region meet to discuss the latest snowpack and avalanche observations, and weather forecast to create the next day's avalanche forecast.  We look at information from the public, other snow professionals, and weather station data to round out our picture.  Share early and often!

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