Bollettino valanghe

Selkirk Mountains

Idaho Panhandle Avalanche Center
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Pericolo valanghe

Wed
Alta quota
4 · Forte
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

A potent storm is delivering heavy snow and strong winds today. The storm increased intensity last night and could result in up to 18’’ of snow with 2.5’’ of water content (SWE) by Tuesday night. Rain is mostly expected today below 5000’. The heavy storm snow will stress existing weak layers and could trigger avalanches on these layers. Natural and human triggered avalanches are very likely today. Travel in avalanche terrain is not recommended.

 

Problemi valanghivi

  • Storm Slabs

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

    Dense and heavy snowfall has created a cohesive slab that is resting on a mix of sugary snow and firm crust layers. These surfaces developed during the first two weeks of March and will create a poor bonding surface for new snow. The new snow combined with increasing winds and warm temperatures will create dangerous avalanche conditions above 5,000 in elevation. Storm slabs will likely be thickest in the Cabinet Mountains. These storm slabs will thicken and become more hazardous throughout the day Tuesday as the snow continues to fall and winds increase out of the southwest. Anticipate slabs to be thicker on north and easterly locations where the winds have tranported fresh snow onto leeward terrain.

     

  • Loose Wet

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

    Modest amounts of loose snow is resting on a firm crust layer below 5,000' in elevation. With heavy rain and warm temperatures "wet loose" slides will be easily triggered at lower elevations. These slides will be small, but may harbor the potential to knock you off you feet or machine in steep terrain today. This problem should diminish as cooler temperatures return to the area on Wednesday.

Avalanche Discussion

A weak atmospheric river will continue through Tuesday evening. Up to 18’’ of snow with a water content (SWE) of 2.5’’ is expected. Moderate southwest wind will deposit more snow on windward faces and could produce wind slabs at high elevations. You’ll most likely find these conditions above 5000’ near ridgelines.

There are two ways the new snow at high elevations could be a problem today. The new snow could be cohesive enough to produce a storm slab avalanche, especially where it falls on a good sliding surface such as a crust.  Secondly, the new snow above 5000’ could also be heavy enough to stress lower layers in the snowpack. The early March crust is a prominent marker in the snowpack and can be considered a good baseline. The faceteted layers above this crust are susceptible to failure and could produce a deeper failure resulting in an avalanche.

As often the case this time of year, you can expect different conditions at different elevations. Rain is expected below 4500' and will create a different problem than higher elevations. Loose wet avalanches are the primary concern below 4500', as rain falls and lubricates the snowpack.  As the snowpack becomes more lubricated it becomes weaker and unable to suport itself. Loose wet avalanches have an unpredictable component to them. A lot of time loose wet avalanches occur when the snowpack gets to a saturation point where it can't support itself anymore, as opposed to being triggered by a person or a snowmobile. Interaction with an avalanche can be a case of being in the wrong place at the wrong time. Consider avoiding travel in avalanche terrain today, especially in runout zones below steep terrain. 

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