Avalanche forecast

Avalanche forecast

Payette Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 4 years ago.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

Highlights

The avalanche hazard is Moderate today.   Very warm temperatures are forecasted through Sunday with mostly sunny skies and no overnight refreezing of the snowpack.  Wet loose avalanche activity will increase as the day warms starting with East facing slopes and moving around the compass through this afternoon.  Multiple weak layers and crusts exist in the upper two to three feet of the snowpack and are now saturated by the melting snow above.   The potential for larger wet loose avalanches,  widespread cornice failures and naturally occurring wet slab avalanches will increase through the day as temperatures warm.  Avoid traveling in or below steep terrain as the snowpack continues to weaken today and over the next few days.

 

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Certain
    Size
    1–1.5

    Today will likely be the warmest day of the year so far.  Our low temperature overnight at the Granite Weather Station(7600ft) was 36 degrees.  These temperatures are not allowing the snowpack to refreeze at night and are weakening the snowpack more each day.  Yesterday, a combo of high clouds and a passing front kept temperatures slightly cooler but today will be a scorcher.  You can expect to see wet loose activity beginning as the sun warms East slopes this morning with an increase by mid-afternoon.  Oftentimes, wet loose avalanches begin as small point releases and can easily grow in size as they travel and grab more wet snow in their path.   Pay attention to the terrain you are near as temperatures warm and avoid steep slopes and terrain traps like gullies and avalanche paths.  

    The avalanche in the photo on the East Face of North Bruin likely occurred on Wednesday and ran just over 2000 verticle feet.  We will definitely be seeing more like this over the next few days.

    N. Bruin Mt. East aspect.

  • Wet Slabs

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

    With a rapidly warming snowpack, meltwater begins to seep down through the snowpack.  As we transition away from a cold snowpack and the persistent weak layers that we have been talking about over the last few weeks get saturated by this meltwater, there is a growing potential for natural wet slab avalanches on the weak layers or the crusts that are now buried between 1 and 3 feet deep in the snowpack.  Wet slab avalanches are like big, rogue waves.  They are unpredictable and relatively rare until conditions line up.  All of the conditions are lining up with the weak layers in the snowpack and potentially record-breaking temperatures.  Temperatures over the next few days will be increasing each day adding to the problem.  Overnight temperatures are not predicted to start cooling off until early next week and the snowpack will take several days to refreeze once temps start to drop.  Wet slabs require a healthy dose of respect as they can be very destructive and unsurvivable if you were unlucky to be the trigger or below one when it started.  They are also very hard to predict.  Avoiding steep terrain and giving the snowpack a chance to heal after this heatwave are your best choices right now.

    Wednesday we observed wet or saturated snow down at least 60 cms(24 inches) in the snowpack.  Both of the crust/weak layers were allowing water to pool above them creating the perfect lubrication for a wet slab above (see photo). Yesterday was slightly cooler with less meltwater in the snowpack but it was still very wet and sloppy.  Today and the next few days will be warmer and sunnier, and will increase the potential for wet slabs through Sunday afternoon.

Avalanche Discussion

Today's Advisory is sponsored by CM Backcountry Rentals and Adventures. Thank You For Supporting the Payette Avalanche Center!  Also, don't forget about the FPAC showing of Buried next Saturday(4/2). The movie will be shown Saturday at the Elkcreek Baptist Church at 7pm.

For better or worse, Spring is here and the temperatures over the next few days will reflect it. Temperatures are expected to climb through the week to 5-15 degrees above normal. With full sun, we will undoubtedly experience an increase in wet avalanche activity. Wet loose avalanches are typically fairly predictable and manageable and involve mostly just the surface of the snowpack. As the day gets warmer and the snow becomes more saturated, the hazard of wet loose avalanches rises and can involve more of the snowpack   Wet slab avalanches are another type of wet snow avalanche and are different beasts than wet loose.  They are much more difficult to predict and can be much larger and more destructive than loose avalanches.  Cornice failure is another side effect of a rapid warm-up,  I don't travel under cornices during warm weather at all.

Our snowpack has several key ingredients that should make you wary of the possibility of wet slab avalanches over the next few days.

  1. Persistent weak layers buried within the upper 2-3 feet of the snowpack
  2. A variety of different crusts in the upper snowpack
  3. Abnormally warm temperatures that are flooding the snowpack with meltwater which is allowing the snowpack and the weak layers to become saturated and lubricating crusts.
  4. Failing cornices- there are some large cornices that will be failing with the heat and bombing slopes below with tons of weight.

As the temps soar this weekend, we need to be thinking of changing avalanche hazards and the possibility of abnormal avalanche conditions.