Bollettino valanghe

Flathead Range & Glacier NP

Flathead Avalanche Center
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Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
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

Facet/crust combinations or surface hoar buried 1-3 feet deep may still pose a danger today. If triggered, these avalanches will be large and break wider than you expect. Avoid convex rollovers and parts of the slope where the slab thins.

Problemi valanghivi

  • Persistent Slabs

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

    Hard slabs, 1-3 feet thick, exist above a facet/crust combo in most locations. A lack of data and observations limits our knowledge about how sensitive these are, but an avalanche of this size will be difficult to escape. Possible trigger points that should be avoided are convexities, rocky outcroppings, and thin parts of the slab. 

    (1/11/2024)

    This 3-foot fracture line is the deepest part of the avalanche crown just east of the WMR ski resort boundary. This avalanche is out of bounds.

    Photo: Mark Dundas

  • Wind Slabs

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

    Northeast winds during the last five days produced thick slabs on atypical slopes. Dune-shaped drifts, hollow sounds, and the ability to walk on the snow surface are all signs you’ve found a wind slab. Consider the consequences of the terrain below you before committing to steep slopes. Loading patterns may be significantly different than what you are typically used to. Seek out terrain sheltered from the wind.

     

    (1/12/2024) Crown in the upper reaches of Shed 9 on Snowslip Mtn Photo: Adam Clark

Avalanche Discussion

A welcome reprieve from the Arctic blast comes today in the form of increased temperatures and light winds. As we all crawl out from behind our woodstoves and blankets, here are a few things to keep in mind. Observations from the last five days have been minimal. 24+ inches of low-density snow and winds gusting in the 80s dramatically changed the snowpack from a week ago. We have a significant storm on the horizon tomorrow.   Before the cold front, there was ample snow available for transport. Strong winds from varying directions created thick slabs on atypical slopes. We have received reports of natural avalanches in all three mountain ranges. Despite the lack of observations, slabs of wind-drifted snow have had ample time to gain strength. A hardy observer found unreactive wind slabs in the Flathead Range yesterday(observation).  Don’t forget the structure before the last storm. We had weeks of high and dry conditions with crusts forming on many aspects. Facets formed around these crusts and/or surface hoar grew above them. The bountiful snow we received in early January buried all of it. Persistent Slab avalanches failing on these layers were reported within the last week (observation).   As the next storm arrives tonight, be aware of what the new snow is falling on. Clear and cold temperatures have already begun to weaken the snow surface. North and northeast-facing slopes were scoured, and south-to-southwest-facing slopes have old hard wind slabs. Both could become a bed surfaces for the new snow to slide on. Continued observations from the field are very much appreciated.

 

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