Bollettino valanghe

Flathead Range & Glacier NP

Flathead Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 7 months ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

You are less likely to trigger a large avalanche on slopes with a strong, supportable surface crust. Consider choosing low-angle terrain if you find soft snow or if the crust begins to thin or weaken. Slopes free from overhead hazards and terrain traps offer a wider margin for safety.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    During the last ten days, we have recorded over 15 slab avalanches breaking on weak layers buried 1 to 3 feet deep. Half have been triggered by riders on the slopes that slid. Most have been large (D2 to 2.5), with a few approaching very large (D3).

    The hot spot for human-triggered avalanches has been the southern Whitefish Range on mid-elevation slopes facing east and south. Natural avalanche activity seemed more common in the Flathead Range on upper-elevation slopes facing north, east, and south. These avalanches propagated widely, and some were triggered remotely from nearby low-angle terrain. 

    Weak layers remain intact following recent warming and may not give signs of instability before failing. Digging and snowpack tests have not been a reliable method for identifying on which slopes this problem exists. Choosing slopes with a stout crust at the surface may be a safer alternative. When in doubt, default to slopes that are not steep enough to slide.

     

     

    (1/16/2026)

    A large, natural slab avalanche on Slippery Bill Mountain in the Skyland area. (7300' - NE - D3). This avalanche occurred in extreme terrain and would have been difficult to escape or survive.

    Photo: Michael Reavis

Avalanche Discussion

Good visibility, firm and fast travel conditions, and mild temperatures will make today a good day for exploration. Mike and I did just that yesterday (Friday) in the Skyland area, where we continued to document large avalanches that recently failed on buried weak layers.

Following this week's warm-up, we expected to find a melt-freeze crust at the surface and hoped this would "cap" weak layers by bridging our weight. To limit our exposure to any lingering hazards, our trip plan identified closed terrain as "any steep slopes without a supportable surface crust." I'll offer that as an option for your travels today with some important notes.

As we traveled, our confidence grew in the distribution and strength of the surface crust, and we felt comfortable stepping out to ride a steep avalanche path.  However, we were surprised to find that the crust became weaker as we descended. This might have been due to the slope angle easing off slightly; lower angle slopes receive less intense sunshine (Nerd Alert: lower angle of incidence for insolation). My suggested improvements to our travel advice:  

  1. Realize that the strength of the surface crust can vary significantly in space and time. 
  2. Choose slopes that give you options to change aspect, or bail into low-angle terrain if the crust becomes thin and/or unsupportable.

Of course, traveling on firm crusts comes with its own hazards: Slick surfaces can lead to sketchy side-hills and uncontrolled slides on steep slopes. Your safest and most enjoyable riding will be on low-angle and shaded terrain, where- rumor has it- some soft snow still exists. 

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