Avalanche forecast

Bitterroot

West Central Montana Avalanche Center
View on map

Avalanche danger

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Out of date — this forecast expired 4 years ago.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

Highlights

While peak instability from the last storm has passed, it is still possible to trigger an avalanche in wind loaded terrain or areas with persistent weak layers.  D3 natural avalanches were reported over the weekend, and the potential for an avalanche 3-5 feet deep still exists. Likely areas are ridge tops and complex terrain like cliff bases and cross loaded gullies.

Avoid slopes with smooth pillows or hollow feeling slab. If you see collapsing, cracking, or whumfing, stick to terrain under 35 degrees. 

Avalanche problems

  • Wind Slabs

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

    Shifting wind directions and strong winds built wind slab on many aspects Saturday and Sunday. Natural wind slab avalanches were reported Sunday across the Bitterroot. Some avalanches in the central Bitterroot were up to D3 in size and over 1000’ feet wide. High winds built slabs low on slopes, and avalanches releasing at cliff base were a common trend Sunday. While these avalanches are becoming increasingly stubborn, the consequences of an avalanche this size are high. Look for wind slabs low on slopes or at the base of rock features. Previous wind slabs may be buried by new snow and be difficult to identify. 

  • Persistent Slabs

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

    The snowpack in the southern Bitterroot is significantly shallower than the rest of the zone. As a result, facets still exist deep in the snowpack at high elevation north aspects. There have been no recent avalanches on basal facets, but the structure is not yet trustworthy. Dig down, and if you find poor snowpack structure, stick to slopes under 33 degrees. 

Avalanche Discussion

A powerful winter storm on Friday and Saturday brought strong shifting winds and heavy snowfall across all forecast zones. The Rattlesnake and Seeley lake zones received the most snow and the strongest winds. The weather changed Sunday and Monday to calm winds, blue skies, and frigid temperatures. Today, winds will be strong from the west, with the potential for an inch or two of new snow. During the last storm, we saw a natural avalanche cycle lasting through Sunday. Large natural avalanches were observed in the Rattlesnake and Bitterroot. Both ski and snowmobile triggered avalanches were reported in Seeley Lake throughout the weekend. 

Coming into today, peak instability from the storm has passed, and avalanches are becoming difficult to trigger. Observers Sunday and Monday mentioned a stubborn slab and difficulty getting cracking or movement. Despite the decreasing hazard, it is still possible to trigger an avalanche large enough to bury you. With the shifting winds, be suspicious of all aspects at the upper elevation and look for loaded features like pillows or hollow feeling snow. Strong winds can build slab low in start zones, and you do not know until you have already skied onto it. A common theme this weekend was slabs at the base of cliffs or rocks. 

Persistent slab hazard still exists in all zones, although stubborn and unlikely to trigger. In Seeley Lake and the Rattlesnake, surface hoar buried 6 inches at the start of the storm is now buried 1-3 feet deep. The best way to identify this layer is to dig in areas you are looking to ski or ride. If you find it, stick to slopes under 35 degrees. Basal facets and deep persistent slab in the southern Bitterroot remain a low probability but high consequence problem. 

 If you are traveling in avalanche terrain today, pay attention to your surroundings. Recent avalanches are the best indicator of instability. With new snow expected today, any avalanche you see is likely fresh. Avalanches on similar slopes to what you are looking to ski or ride is a red flag that overrides any snowpit or stability test.

Let us know what you see out there today by submitting an observation. If you see an avalanche, even if it looks old, please send us a picture! 

Ski and ride safe.

Regions covered