Avalanche forecast

Seeley Lake

West Central Montana Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Lingering pockets of surface hoar and deeper buried facets may be triggered by skiers and riders above 7000' in the southern Missions and Swans. Avoid convexities over 35º and shallow areas around rocks and ridgelines. Below 7000', warm temperatures have created crusts that reduce riding quality and limit avalanche potential. 

Avalanche problems

  • Persistent Slabs

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

    There are two persistent weak layers of concern in the Seeley zone. 

    The first is a layer of buried surface hoar that can be found in both the southern Missions and southern Swans at elevations above 6000. It can be found 8" to 12 " below the surface. Slides were easily triggered on this layer on Saturday, and several were triggered yesterday in the Lake Dinah area, according to an observation received after the initial publication of the forecast this morning. In the Missions, this layer can be found on all aspects, although southern aspects may be less touchy. In the southern Swans, it is somewhat patchy. Skiers and riders are likely to trigger slides on this layer in the right terrain. Likelihood can be reduced by avoiding convex rolls over 35º and unsupported slopes. 

    The second layer is deeply buried facets that may still exist on shaded upper elevation terrain in the southern Swans. The recent warm temperatures are certainly helping basal facets bond. However, in shallow north-facing terrain, weak sugary facets can still be found below a cohesive slab. It is unlikely to trigger this layer, but it could happen with just the right shallow trigger spot. Sledders high marking a slope may be able to trench down and trigger this layer. Avoid shallow areas in upper elevation north aspects, such as around wind swept ridges.

    (1/14/2023)

    D1.5 Avalanche that slid on buried surface hoar near Marshall Lake

    Photo: Caleb Kesterke

Avalanche Discussion

Overall the avalanche hazard is trending lower. Mild temps, calm winds, and isolated new snow have contributed to a mostly stable snowpack, with the exceptions noted above in the problems. Most notable is the surprise overproducing storm that hit the northern Bitterroot. Elsewhere, there is just enough reactivity and uncertainty in the upper elevation layers to keep it at moderate. Buried surface hoar is a tricky one, the touchiness dropped considerably over the weekend in both the Rattlesnake and Seeley zone, but it's still down there waiting for someone to hit the sweet spot and trigger it. Basal facets in the southern Swans and Southern missions remain a slight concern that is an unlikely but still plausible and high consequence problem.   At least in the Rattlesnake, the basal facets have bonded and become unreactive, so we can remove them from the problems list.  

Throughout the forecast area, crusts extend to 7000' and lower the possibility of avalanches at mid-elevations. Despite the low hazard, exceptions exist, and avalanche conditions could be found. Continue to stay alert to changing snow conditions and red flags as you travel.

The lower elevation snowpack, unfortunately, continues to shink. In the central Bitterroot, slopes are almost bare to 6000' on the south aspects and 5300' on the north. Wet loose avalanches have been a concern for the past week at lower elevations. Today temperatures should be cool enough today to keep snow surfaces mostly frozen. The freeze-thaw cycle has reduced the likelihood of natural loose wet activity if it does warm up. You could kick off small loose wet on steep slopes if temperatures climb higher than forecast.

We received a lot of high-quality observations over the weekend. Thank you to those who sent them in. You can submit new observations here.

Ski and ride safe

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