Bollettino valanghe

Flathead Range & Glacier NP

Flathead Avalanche Center
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Pericolo valanghe

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

In sintesi

It is unlikely, but not impossible to trigger a large slab avalanche on isolated terrain features above 7000 feet. Probe around to see if you feel a hard and supportable crust under roughly 2 feet of snow. A person is less likely to trigger a large avalanche where this thick crust exists. If you decide to step out into steep terrain, ride one at a time while keeping your partner in a safe location.

Problemi valanghivi

  • Persistent Slabs

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

    Observations below roughly 7300 feet suggest weak layers buried in the snowpack got destroyed by warm temperatures and rain. The other similarity in recent observations is that slopes facing south and west appear to have a stronger, more stable snowpack structure than northerly aspects. That offers up many options in our forecast areas for steeper riding. If you decide to climb high into the alpine, be skeptical of slopes that face to the north. This is where buried weak layers from early December are most likely to exist.

    (12/13/2023)

    12/1 surface hoar was buried 2-3 feet deep. Snowpit tests produced ECTP17 on a wind-sheltered NW slope at 7300'.

Avalanche Discussion

10 to 20 inches of recent snow from this past weekend continues to show stable signs. The only recent avalanche activity reported in the past week are small (D1) loose dry sluffs. 

Thankfully, wind speeds have remained below thresholds for transporting snow. Some exceptions apply at the highest ridgelines, where observers recently found blowing snow and wind-scoured surfaces. Although I would suspect these slabs to be mostly unreactive, I still suggest riding around wind-drifted features in steep terrain, especially above consequential terrain features.

Persistent weak layers buried in the middle of the snowpack and near the ground appear to have mostly gotten destroyed by warm temperatures and rain earlier this month. There is higher confidence of this happening below roughly 7300 feet in elevation, and likely much higher up. Yesterday, we did find a crust up to our high point of 8100 feet in the Flathead Range. This means that rain and warm temperatures likely made it to the tallest peaks in our forecast area.

We did find one troublesome snowpack structure on a wind-protected, northwest aspect at roughly 7300 feet. For whatever reason I can’t explain, the crust was thinner and more breakable in this location than in any other spot we dug, including slopes higher up on the mountain. Something worth noting is that this was the only wind-protected northerly slope we could safely access. Slopes with similar characteristics jumped out as ones not to be messed with. A triggered slab would break 2 to 3 feet deep with no warning signs prior to it failing. 

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