Avalanche forecast

Bitterroot

West Central Montana Avalanche Center
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Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Today avalanches large enough to bury a person will be likely. Very large wet slab avalanches on the March 1st crust are possible. Danger will rise throughout the day with warming temperatures. Avoid traveling on or below cornices, slopes over 35 degrees, and areas of solar warming like rocks and cliff bands. Look for rollerballs and sticky wet gloppy snow as a sign to turn around and exit avalanche terrain. 

Avalanche problems

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–3

    Human and naturally triggered avalanches are likely today. In the last 48 hours, warming temperatures led to widespread loose wet slides large enough to bury a person. With no refreeze last night below 8000 feet, wet loose avalanches could increase in depth and size today. 

    The March 1st crust, buried one to two feet deep, provides a slick sliding surface, making it possible for very large wet slab avalanches to occur. As the warmth continues, bonds break down, and water percolating through the snowpack can lubricate the crust. Just how much warmth and water it will take to cause an avalanche is unknown. Wet slabs are unpredictable, can not be checked by standard snowpack tests, and can release unexpectedly. Wet slides can entrain considerable snow, gouge through snowpack and run long distances. Avoidance of avalanche terrain is the best management. 

Avalanche Discussion

In the last 48 hours, a rapid rise in temperatures dramatically changed our snowpack. It has been thoroughly warmed and destabilized. All aspects are affected. Temperatures remained above freezing overnight below 7500’ in the north and 8000’ in the south of the forecast zone. Any refreeze that takes place this morning will be shallow and quickly thawed by rising temperatures and solar warming. 

Yesterday the temperatures in the mountains reached 51º at Saddle Mountain (7940ft) in the southern Bitterroot, 62º at Lolo Pass (5240ft), and 51º at Stuart (7400) in the Rattlesnake. D2, wet loose slides occurred in Jenny Bowl, and in the southern Missions on test slopes, skiers easily triggered wet slides.

Wet problems are unpredictable, and don’t respond to standard snowpack tests. The best strategy is avoidance. The standard advice is to either manage aspects and transition to colder shaded areas throughout the day or get an early start to end your skiing day before midday high temperatures. Today, you’ll be hard-pressed to find any snow that isn’t wet and destabilized. 

We transition to a spring diurnal snowpack with freezing temperatures forecast for this evening. The danger level will drop at night with freezing temperatures and increase throughout the day with rising temperatures. This cycle will likely continue for the rest of the season.

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Ski and ride safe

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