Avalanche forecast

Avalanche forecast

Payette Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 2 years ago.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

Highlights

Triggering a dry loose avalanche 1foot deep on slopes steeper than 35 degrees will be likely today in wind and Sun sheltered terrain. SW winds upwards of 20mph have made triggering a 1-2' thick wind slab possible in leeward terrain.

Triggering a deep persistent slab avalanche up to 3 feet deep has become unlikely yet remains a possibility, especially where the slab is thin.

Use cautious travel protocols on and near slopes steeper than 30 degrees and only expose a single person to avalanche terrain at a time. Avoid wind-loaded terrain and use extra caution near cornices that are overhanging.

 

Avalanche problems

  • Loose Dry

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

    Snow over the last 24 hours came in on top of weak facets and hoar crystals that formed on the surface during the last week while we were loving the few sunny days. This new snow, now around 10" on Tuesday morning does not have a great connection and was running on steep slopes with ski cuts on Monday.

    Use extra caution on slopes that are steeper than 35 degrees and that are sustained or where there are potential hazards of terrain traps like gullies or cliffs. This problem is most likely found where the Sun and wind have not broken down weak snow that formed on the old surface. Expect 1-2' deep dry loose avalanche potential. Sluff management techniques are going to be prudent for big exposed lines as the moving snow may push you where you would rather not go.

    (3/11/2024)

    The new 6" of snow was dry and loose and ran easily on the North aspect of Sgts on this 35-38 degree slope.

  • Wind Slabs

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

    Winds have been fairly active over the last 24 hours and have gusted upwards of 20mph out of the SW and were sending snow into leeward terrain, mostly North and East aspects. Slabs that formed previously have likely healed but be prepared of the possibility of triggering a 1-3 foot deep wind slab in upper elevation leeward terrrain.

    If you are seeing cracking or hearing whumphs find another route...Look for signs of wind loading as different terrain may load different aspects. Extreme terrain or consequential terrain like exposure or terrain traps are going to amplify the consequences of this problem. 

    (3/11/2024) Cornice’s growing bigger lip’s from moderate gusty WSW winds .

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1–2.5

    Recent saw tests (PST 47/100 end on March 11th) on this layer show a very hard-to-trigger slab with remaining potential to propagate a crack over a distance...We have seen evidence from natural avalanches and human-triggered avalanches this last week. Layers of surface hoar were buried just before the last 3 plus feet of snow that we have gotten since February 25th---A very stormy pattern with strong winds out of the SW and continued rounds of snow with it, and in between storms there were periods of clear skies where weak layers of surface hoar and graupel formed, now buried within the upper 2' of the snowpack. 

    Many steep slopes likely slid mid-storm? Visibility was poor during most of the storm cycle as snow and winds as well as dense clouds shrouded the peaks most of the time.  Triggering these layers is becoming difficult and is becoming less likely. 

    ***Riders on snowmachines are most likely to trigger these layers, especially in areas where the slab or the snow is thin or shallow and rocky or near trees or other areas.

    Observations of this problem have been in wind and Sun sheltered terrain, with crowns just below the ridgeline mainly on East, Northeast, and North aspects. There is about 100-120cm or 3-3.5' of snow above this layer ( a thick, pencil-hard slab). Over the last 2 weeks, we have gotten a lot of good observations from riders and sliders from triggering avalanches and thankfully the outcomes were learning lessons from just a close call. 

    Extra caution is needed on steep slopes, 35-45 degrees, where the slab can hang on above these weak layers.If you do travel in or around slopes steeper than 35 degrees,  it stack the odds in your favor and only expose 1 person at a time in your group while you watch from a safe spot well away from where the avalanche could run out to.

     

    (3/9/2024)

    Looking at South towards the Avalanche triggered by snowmobile on  3/7/24 HS-AM-R2-D2.5

    Photo: George Halcom

Avalanche Discussion

Human-triggered avalanches have been reported by both riders and sliders last week. Weak layers have failed or gained strength. A lot of steep terrain can be traveled on without consequence, yet there may be an area where luck may not be on your side...The game or the message remains the same, use extra caution, on slopes 30-45 degrees, and don't put your group in the runout, or in avalanche terrain together at the same time.  Group up far away from steep slopes.

Keep the odds in your favor by doing simple things like digging a pit, wearing a transceiver with fresh batteries, checking your partners for transceiver function, Shovel and probes on your back, traveling one at a time through terrain steeper than 30 degrees, and watching your partners from a safe spot are going to be prudent to success in the mountains.  

Check out all of the great observations from sliders and riders who have reported triggering avalanches throughout the week. They will be entered in our monthly FPAC drawing for submitting an observation, and you can too!

Today's Advisory is sponsored by Dakine.