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

Increased clouds today will limit some warming, but when the sun shines through, triggering wet loose avalanches will become possible. Watch for signs of instability, like rollerballs, point releases, or fresh wet snow avalanches. If you see these or find mushy, wet snow, it is time to exit avalanche terrain or move to more shaded slopes. Larger persistent slabs are unlikely, but poor snowpack structure still lingers in isolated terrain. 

This will be our last forecast of the 23/24 season. We will issue a General Avalanche Information product tomorrow with general spring backcountry travel advice. 

Problemi valanghivi

  • Loose Wet

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

    With increased clouds and some isolated snow showers in the forecast today, we can expect less warming than yesterday. However, some sunshine will still make it through the clouds, and when it does, wet loose avalanches will become possible on sun-affected terrain.  

    6-12 inches of snow from the past week sits on top of a stout crust. After a couple of days of warming, most aspects except north will have a melt-freeze crust at the snow surface this morning. It won't take much sun for this crust to break down and for the snow to become wet and slide on the smooth bed surface below. 

    The typical progression of wet loose avalanches involves rollerballs, and small point releases, leading to larger wet loose avalanches. If you encounter rollerballs or small wet loose avalanches, expect larger ones to follow. Remember that even small avalanches can have serious consequences in consequential terrain. 

    If you find yourself in mushy, wet snow or see natural, wet loose avalanches, it is time to step back out of avalanche terrain and be aware of what terrain is above you. You can also move to cooler, shaded slopes to find drier snow.

    (3/20/2024)

    Several natural wet loose avalanches on the southeast side of Murphy Peak. 

    Photo: Arden Feldman

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1.5–2.5

    Persistent slab avalanches remain unlikely, but high consequence if triggered. The primary layer of concern is weak snow surrounding a crust in the middle of the snowpack. This problem has been unreactive and not producing avalanches, except for one avalanche in the southern Bitterroot on March 12th, which resulted in a fatality. 

    You will not see red flags like cracking, collapsing, or whumfing before triggering an avalanche. Slopes with previous ski tracks are still suspect, and it is possible that the second or third skier on the slope could trigger the avalanche. The only way to identify this problem is to dig in the snowpack. If you find a crust with a thin layer of weaker snow above or below it and a slab above, recognize the potential for a larger avalanche. If you want to avoid the issue completely, avalanches are unlikely on slopes under 30 degrees in slope angle.

Avalanche Discussion

Unfortunately, the time has come for the avalanche center to begin wrapping up operations for the 23/24 season. Thank you for another great season! This will be our last forecast of the season. Tomorrow, we will issue a General Avalanche Information product with general spring backcountry travel advice. 

Unlike our Forest Service neighbors, we are a nonprofit avalanche center, and we do not have the resources to continue producing avalanche forecasts later in the spring. Please consider donating if you value our work and would like to see us grow and improve our products in the future. We’re already looking forward to next season - let’s hope it’s snowier than this one!

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There is some uncertainty in today’s forecast. Wet loose avalanches are the primary concern today, but increased clouds may prevent significant warming. If the sun doesn’t make it through the clouds, the danger may not reach moderate. However, yesterday, observers found wet surface snow even during mostly cloudy conditions. The danger will start at Low this morning and, depending on the amount of sunshine that makes it through the clouds, likely reach moderate by the afternoon with wet loose avalanches becoming possible. 

We removed the wind slab avalanche problem today. Snow showers today could produce a quick inch of snow but are unlikely to create any fresh slabs. Over the last few days, observers found limited signs of wind slab instability, with no reports of wind slab avalanches. However, isolated lingering wind slabs could still be found along the highest ridgelines. If you see signs of instability like cracking or collapsing, step back to lower-angle terrain. 

Larger persistent slabs and wet slabs are unlikely today. However, if you find an isolated area with poor snowpack structure or lingering wet snow in the middle of the snowpack, consider the consequences of a large and destructive avalanche. 

High pressure will build tomorrow into Tuesday with mostly sunny skies and increasing temperatures. Expect the avalanche danger to rise with more widespread wet snow avalanches. 

Be sure to continue using safe travel practices as you travel in the backcountry this spring. Only expose one person at a time to steep slopes, regroup in safe zones, and always carry your rescue equipment. Give cornices a wide berth when traveling along ridgelines, and avoid being under them when the snowpack is not solidly frozen. 

Please continue to submit observations even as our forecasting season comes to an end. The information helps us wrap up our season, and provides valuable information for those continuing to get out this spring. 

Ski and ride safe!

Regioni coperte