Bollettino valanghe

Bollettino valanghe

Payette Avalanche Center
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Pericolo valanghe

Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

You are likely to find soft slabs of new snow up to 12" thick across multiple aspects and elevations. Conditions will be most sensitive above 7000' on east-facing slopes. Newly buried weak layers (such as surface hoar and graupel) are creating dangerous avalanche conditions.

Today's avalanche forecast is sponsored by Rossignol

Problemi valanghivi

  • Storm Slabs

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

    48 hour storm totals range from 6-12" across most of the forecast zone. Most of the new snow fell yesterday before noon. This built soft slabs of new snow around a foot thick. Yesterday, PAC forecaster George Halcom found touchy new storm snow conditions north of Brundage Resort. You can read his observation here. On West Mountain, I found similar conditions. This storm slab will be thickest and most sensitive above 7000' on east-facing terrain features. New storm snow will be most sensitive in wind-loaded locations just below ridgelines. 

    This storm slab will likely be transitioning to a persistent slab this week. Yesterday, George and I both observed a buried weak layer of surface hoar and graupel about 25 cm (10") down. New snow was failing easily at this interface. In wind-protected areas, the new snow is softer and was on the edge of forming a slab yesterday. As new snow continues to pile up this week, expect this newly buried weak layer to become increasingly reactive.

    (2/26/2024)

    Looking South at the cornice kick triggered avalanche that I was able to get to fail easily on the East wind loaded aspect.

    Photo: George Halcom

Avalanche Discussion

EMERGING PERSISTENT SLAB PROBLEM

Yesterday, on West Mountain, I observed new storm snow failing easily on a newly buried weak layer of surface hoar and graupel about 25 cm (10") down. North of Brundage Resort, George found similar conditions. As this new snow gains strength and forms into more of a slab, expect to see Persistent Slab on the menu this week. We both found these weak layers on east-facing aspects between 7000' and 7600'. However, that is not the only areas where you might find them. We both observed a layer of small-grained facets nearly two feet down that also showed the potential to propagate. On other, more solar aspects, you may find melt-freeze crusts.

Why is this significant?

  • Persistent slabs are much trickier to navigate than storm or wind slabs. Persistent slabs fail on persistent grains (i.e. surface hoar) and can propagate across much larger distances. 
  • Looking at the forecast, we could see another 1-2+ feet of snow by Saturday. All of this new snow will be adding weight and additional stress to these newly buried weak layers, creating more dangerous avalanche conditions.
  • Today, you may find sensitive new snow conditions. These will most likely be soft slabs, except for just below ridgelines where new snow will be denser and more sensitive. From Wednesday on, expect avalanche activity to become larger in size and more sensitive to triggering on these newly buried weak layers.

Don't miss the monthly State of the Snowpack Talk this Friday, March 1st from 6-8 PM at Broken Horn Brewery

Want to help improve the avalanche forecast and enter your name to win an awesome raffle prize?

You can do both by letting us know what you're seeing and submitting an observation. Submitting an observation using our new observation platform is quick and easy to use. Every observation submission gets entered into the FPAC monthly raffle and you could win some great prizes courtesy of the FPAC. Observations (such as these recent ones) can greatly improve information for avalanche forecasts.