Avalanche forecast

Seeley Lake

West Central Montana Avalanche Center
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Avalanche danger

Fri
Alpine
1 · Low
Treeline
1 · Low
Below
1 · Low
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Highlights

For the most part, the snowpack is well bonded and stable. Outside of isolated pockets of wind slab, it is unlikely to trigger an avalanche today. Take care in upper elevation wind loaded terrain where you could trigger small wind slabs in steep start zones and on the edges of cross loaded gullies. While not a problem in benign terrain, these wind slabs could push skiers and riders into and over terrain traps if triggered in the wrong spot. 

Avalanche problems

  • Wind Slabs

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

    Westerly winds were strong and transporting snow yesterday. Upper elevations, below ridgeline, is the most likely place to find wind slab. However, some areas, such as the central bitterroot, saw swirling winds that wrapped around terrain features depositing snow on multiple aspects. Cross loading on gullies was taking place. 

    Despite widespread transport, wind slab was not reactive in all areas. Where found, such as north aspects in Bass Creek, it was generally small and thin but big enough to cause problems in steep terrain containing terrain traps. 

    It will take some investigation to determine if the wind slab has bonded in the area you are touring, but start with the assumption that it hasn’t. Always approach wind-loaded slopes with suspicion. Test small, safe, representative slopes for reactivity before stepping up to bigger terrain.  Any shooting cracks or movement of small slabs and chunks is a warning sign that windslab exists.

Avalanche Discussion

High pressure and inversions are on the menu this week. Yesterday saw clear skies above valley cloud. Temperatures reached 27º at 8000 feet. Winds were strong out of the west, reaching 25MPH at Point 6. Temperatures felt colder due to windchill. The sun impacted the snow on south faces, while shaded aspects remained light and dry.

Today temps could reach the low 30’s, and winds are light with moderate gusts out of the southwest. 

Overall hazard remains low. Solar warming and warmer temperatures will create heavy snow on south aspects, and small wet loose avalanches are possible. The main concern is wind slab. Strong winds yesterday were moving snow, and windslab is a concern in the alpine. Above 6500’, winds were swirling around terrain features, depositing snow on multiple aspects and cross-loading slopes. 

The deeply buried facets in the southern Bitterroot are worth noting. Above 7400’ on shaded aspects, the propagation saw test (PST) shows a likelihood of propagation in certain places. This is a very low likelihood but high consequence layer; it is very stubborn and unlikely to avalanche naturally. However, there is an outside chance that skiers and riders could trigger this in just the right spot. Avoid steep convex slopes, shallow windswept, and rocky areas on upper elevation north slopes in the southern Bitterroot. 

With the warm temperatures, blue skies, low hazard, it is easy to get lulled into a sense of security and take the stability for granted. Don’t get complacent. Hazards still exist, and avalanches happen at low danger. Stepping into steeper, more committing terrain increases the consequences of any avalanche, even small ones that may be enough to push you over cliffs or into terrain traps. Continue to practice safe travel techniques and watch for red flags.

We received several high-quality, informative public observations over the weekend. Thank you to all those who sent them in; please keep them coming. You can submit observations here.

Ski and ride safe

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