Bollettino valanghe

Elkhorns

Wallowa 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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Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

If you make it above the rain/snow line and find snow stiffened by the wind it's possible you could trigger a wind slab.  Wind slabs will primarily be found at upper elevations where light amounts of new snowfall have been drifted by the wind.  Look for visual clues such as ripples in the snow surface, dune-like formations, or cracking to help you avoid this problem.  

This forecast is sponsored by Anthony Lakes Mountain Resort.  

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    It's most likely you'll find wind-transported snow that's been packed into a slab at upper elevations today.  Warm daytime highs yesterday, rain on snow, and an elevated snow level have capped mid and low-elevation terrain with a crust.  Our best guess is that above the rain/snow line, there is some fresh snow that can be moved around by the wind.  If you observe a textured snow surface, feel harder snow over softer snow, or see cracking these are clues from Mother Nature. 

    (12/14/2024)

    A rippled surface texture indicates the wind has affected the snow.  

    Photo: Karen Morse

Avalanche Discussion

Thanksgiving Drought Layer:  Each time a layer of weak snow receives a new load, an opportunity arises to learn more about whether it is gaining strength, losing strength, or staying the same.  The greatest challenge is we cannot predict the tipping point that could lead to an avalanche.  One of the best ways we can monitor a layer of concern is to dig into the snowpack, look for signs of gained strength, and perform snowpack tests.  

Uncertainty:  Unfortunately we can't scan a slope or terrain feature to determine the distribution of a suspect weak layer or the hardness of snow above it.  Some old and wise snow professionals simply choose to avoid slopes >30 degrees when a known persistent weak layer is buried in the snowpack, with a slab above it.  Across this vast landscape, we've found the Thanksgiving Drought layer gaining strength in our snowpits.  This layer is also becoming more deeply buried in areas where the wind isn't removing snow.  Weak layers need compression and insulation to gain strength.  

So what:  Using good travel protocols, exposing one person at a time, regrouping in safe zones, and sticking to terrain less than 30 degrees will greatly increase your security.  Digging a snow pit and testing the suspect layers can lure you into a false sense of security.  There is such as thing as false stable results.  A weak layer may not fail while conducting a snowpack test, but it doesn't mean the snowpack structure is good.  Remember there's so much spatial variability in this landscape, and even triggering a small avalanche with a dangerous runnout zone can have severe consequences.  

Observations:  Thanks to everyone who has submitted their observations this week.  We hope to continue this trend of receiving an increase in public and pro observations.  Remember, you are helping the forecasters fill their gaps in knowledge.  

Regioni coperte