Bollettino valanghe

Salmon River Mountains

Payette Avalanche Center
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Pericolo valanghe

Fri
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

Fresh wind slabs up to 1.5 feet thick have likely formed where northwest winds upwards of 30 mph have drifted snow and may be sensitive to the weight of a person.Triggering a persistent slab avalanche as thick as 2 -3 feet remains possible—especially in wind-drifted terrain. The best way to reduce your odds of triggering a slide is by sticking to wind sheltered, lower-angled terrain without steep slopes above you. Avalanches may be triggered remotely—from below, above, and to the sides of steep slopes.  

Problemi valanghivi

  • Wind Slabs

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

    Be on the lookout for sensitive snow in areas exposed to the wind. Especially in areas north of McCall, where up to 7 inches of new snow and gusty winds ranging from SW to recently NW into the 30mph range at ridgetop has moved new snow in odd places.

    Watch for fresh windslabs 4-16 inches thick on multiple aspects creating hazards on leeward slopes. Stay far back from steep terrain near cornices and ridgelines. Sounds like whumphing and other red flags or signs like cracking may not appear until it is too late as the new snow could start to overload previous weak layers deeper in the snowpack.

  • Persistent Slabs

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

    We are watching the snowpack, and unfortunately the situation remains the same across most of our advisory area as well as within Idaho and Oregon:

    A thick, well preserved layer of surface hoar (plus or minus a crust, depending on your aspect and elevation) is buried about 2-3' deep, and averaging slightly shallower in the West Mountains (1-1/2'). This problem has been highlighted on wind-loaded terrain mainly above 7,500' from the last cycle of natural and human-triggered avalanches. This layer formed during several days of dry weather and cool clear nights in early February and was quickly loaded and preserved with some snowfall. It appears to be responsible for a large portion of the recent avalanche activity in both zones & was likely the culprit in a remotely triggered slide. 2 feet deep is the ideal triggering depth: thin enough in many areas for a human to trigger, but thick enough to produce large and dangerous avalanches. We observed unstable test pit results at the crown of the aforementioned remotely-triggered slide Monday and have seen it persist with unstable results again on Tuesday 3/3 (see the photo to the right). 

     

    The best way reduce your risk is by avoiding slopes over about 35 degrees, especially those that are of rocky, wind-affected, alpine nature. Pay attention to what's below you—look for trees, rocks, gullies, and other terrain traps.

    **Good spacing like one at a time and regrouping in solid safe zones are easy insurance policies to take out if you choose to travel near avalanche terrain.

     

    (3/3/2026)

    Shallower burial depth of surface hoar from 2/14 in the West Mtns zone here on No Business Mountain. A pit on a north aspect  reveals unstable test results on March 3rd. 

    Photo: George Halcom

Avalanche Discussion

Phew, that's a long avalanche problem description above, but some things are worth covering in detail. Some other FAQ's regarding the current avalanche conditions...

Q: Where are conditions most dangerous?A: The last storm produced widespread avalanche activity, with natural and human-triggered avalanches occurring across both forecast zones. This does not mean that you will see remnants of giant slides everywhere. Many were primarily in upper-elevation terrain above 7,500 feet, where terrain is prone to receive more wind,  is well-connected, and forms more obvious avalanche paths. However, many of the human-triggered avalanches as of late have been on small, steep, and treacherously-treed terrain-trap features. Where the slab thickness above the weak layer is around 2' seems to be the "sweet spot"—these are the areas where you are most likely to trigger a slide. Check for weak snow where you ride today—and remember that lack of evidence is not evidence of lack. 

Q: Are there areas where conditions are less dangerous?A: We have not heard reports of persistent slab avalanches, seen natural activity, or found much for unstable snow below ~7,000 feet. Both zones and the surrounding areas received a fair amount of rain during the last storm. The snowpack below this elevation exhibits a different slab/weak layer relationship than the snow above the rain line. The mountains around Big Creek [& the neighboring Warm Lake] have received a little less snowfall and more rainfall this season, and instability has generally been limited to wet slides or to areas where the wind has formed thicker drifts above the weak layer.

Q: Is it getting better?A: Yes. But the tougher question is by how much? With an especially pesky persistent weak layer like this one, there are no clear indicators of when the risk of triggering an avalanche has decreased to an acceptable level. Some important clues include decreasing signs of instability, such as a lack of human-triggering, a lack of failure in snowpit tests, and a prolonged period with no new loading from snowfall or wind. The consensus is that we're not there yet. Note that weak snow buried ~2 feet is deep enough that warm temperatures are changing the surface/slab above this weak snow, but not "strengthening" the weak layer itself. 

Q: What should I do about it?A: Glad you threw me an easy one. With no clear answer about how much the snowpack has stabilized, we need to offset the uncertainty with a healthy margin of safety in our terrain choices. In simple terms, this means continuing to choose conservative, lower-angled terrain that isn't threatened by steep slopes from above. And unfortunately for those who do not love crusts, the safest terrain lies where rain has fallen during the last storm and warm temperatures of recent days have melted and refrozen a larger portion of the snowpack. 

Regioni coperte