Bollettino valanghe

Bitterroot

West Central Montana Avalanche Center
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Pericolo valanghe

Mon
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

Avalanche danger will start at Low, and become Moderate as temperatures warm and crusts break down. With overnight temperatures hovering just above freezing, you are likely to encounter slopes that did not refreeze overnight. If you find yourself sinking into wet, mushy snow, it's time to move to shadier aspects where a surface crust remains, or get out of the mountains altogether.

Moderate hazard at upper elevations is for the southern Bitterroot, where skies will be sunnier and temperatures will be warmer. Elsewhere in the Bitterroot, upper elevation danger will stay Low.

Problemi valanghivi

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Multiple forms of wet avalanches are on the menu today, with wet loose being the most likely. Overnight temperatures barely brushed freezing in most areas, and a lack of a hard freeze will give nature a head start.  Warming will occur first on steep solar aspects, but could include all middle and lower elevations by the afternoon. Cloud cover will slow the warming, but sun could peek through in the morning and speed the process up.

    Wet Loose: These avalanches start from a single point such as your skis, machine, or snowboard, and fan out downhill, growing and entraining snow as they move. They can also start naturally from cliffs or trees, so be aware of what terrain you are travelling under during the heat of the day. Loose avalanches are most likely to occur on southerly aspects, but will become possible on all aspects during the warmest part of the day.

    Wet Slab: While likelihood has decreased over the past week, our snowpack has demonstrated the potential for wet slab avalanches. Water is still moving through the snowpack, and wet slabs are notoriously difficult to predict. With their large and destructive nature, these should be in the back of your mind anywhere you find wet snow. 

    Cornice: Snowfall and strong winds built gargantuan cornices this past month. Cornices become more likely to fail with sustained warm temperatures, which we have seen for the last 4 days.

    Glide: Glide cracks have been opening up in the Bitterroot, and we’ve seen the entire depth of snowpack slide downhill in some places. Glide avalanches occur on steep rock slabs while water is actively flowing through the snowpack. With record breaking daily high flows on the Bitterroot, this is evidence that water is moving through the snowpack.

    The best way to avoid wet avalanches is to head to your car, or to shady slopes, as you see roller balls or begin to sink down into mushy snow. This dry to wet transition can happen quickly. Ensure you have an exit strategy before committing to spending time on solar slopes. Don’t travel below glide cracks and cornices, and give cornices plenty of breathing room as you travel along ridgetops.

    Natural wet loose avalanches in the Rattlesnake. We can expect to see similar debris piles in the Bitterroot region today.

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1–2

    High elevations in the Bitterroot received 4 to 8 inches of snow this week, and winds have stayed strong enough to move snow. While most snow surfaces were warmed in the last few days, backcountry travellers found lingering dry snow up high, and field teams saw blowing snow at 9,000 ft and above yesterday. Wind slabs in these areas rest on a firm surface, which means if you do trigger an isolated wind slab, it could travel fast and far.

    If you get up high today, pay attention to the elevation at which you start finding dry surface snow (and please let us know by submitting an observation here). Once this happens, you’ll find wind slabs in isolated areas. Think leeward sides of ridges and rollovers, downwind of cliffs and large rocks, immediately under cornices, and in cross-loaded gulleys.

    Wind slab in the Bitterroot two days ago. Some of these wind slabs will remain dry on high elevation northerlies.

Avalanche Discussion

Another day with above freezing temperatures and no new overnight precipitation means conditions will be similar to the last few days. Mountain weather stations indicate an overnight freeze line around 7,000ft. Expect most crusts you encounter to break down quickly this morning. While it feels like spring in the valleys, mid and upper elevations haven’t fully switched their mentality, and neither should you.

Today's avalanche problems are mainly due to softening and weakening snow. South aspects will warm first and most, but above freezing temperatures mean wet avalanche problems will be possible on all low and mid elevation aspects. Cloud cover will inform how quickly or slowly snow surfaces soften, and cloud coverage weather forecasting is fickle by nature. If we have less cloud cover than expected, the avalanche hazard will rise from low to moderate more quickly. Cloudy skies in the Rattlesnake, Northern Bitterroot, and Seeley region will temper, but not prevent, afternoon snow surface warming. As you move south in the Bitterroot, expect less cloud cover and more warming.

Upper elevation northlies likely haven’t and won't soften, and the snowpack has not fully completed its spring transition up there. Due to cooler temperatures combined with thick cloud cover, hazard at upper elevations has dropped to low in most places. We don't expect extensive surface warming up high, and crusts will be slower to break down there. Low danger doesn't mean no danger, and before committing to a consequential slope, dig down and hunt for obvious weak layers (dry or wet), and then consider the consequences. If you find dry surface snow, watch for lingering windslabs.

While avalanche hazard often becomes simpler to manage in the spring, don't let yourself be warmed into a sense of complacency. With the combination of dry/wet problems and changing weather conditions throughout the day, pay attention to how the snowpack changes today – both spatially and temporally. Look for signs of instability such as recent avalanches, rapid warming, roller balls, and cracking underfoot. 

Today marks our last regular forecast for the 2025-26 season. We truly couldn't have done it without everyone's help, with 185 of our 280 observations coming from y'all! As the spring season continues, stay tuned in.  Submitting an observation helps the forecast team produce accurate and relevant general products as conditions change. Enjoy the tail end of this wild season!

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