Boletín de aludes

Silver Valley & Bitterroot Mountains

Idaho Panhandle Avalanche Center
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Peligro de aludes

Sat
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 2 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Recent field observations and weather trends have led us towards an increasingly stable upper snowpack that continues to rest upon widespread persistent week layers left from the end of January—the January Drought Layer (JDL). Triggering a larger dangerous avalanche is still in the cards if you travel on steep, rocky areas of shallower snowpack, or where drifting builds uneven slab depths influenced by terrain twists, turns, or bends. Given the lingering uncertainty in the snowpack and multiple contributing factors, it’s best to maintain a conservative travel approach.

 

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    2

    Weak layers - surface hoar, faceted grains, and a faceted crust - around two feet deep are the culprit of lingering instability in the upper snowpack. Snowpack tests on slopes near treeline down to about 5,500 feet continue to produce ongoing failures in these weak grains - albeit with harder force. You may find isolated places with buried surface hoar on north to east-facing slopes, while southeast through south to west-facing slopes harbor a breakable crust with facets looming above and below. While deeper weak grains are showing evidence of strengthening, the ability to affect weaker snow and trigger a slide appears directly influenced by overlying slab depth.

    Photo: Izzy Davis

Avalanche Discussion

Today is likely the last full day to get out into the mountains before the impending atmospheric river hits our region. Recent field observations and weather trends have led us towards an increasingly stable upper snowpack that continues to rest upon widespread persistent week layers left from the end of January—the January Drought Layer (JDL). This leaves us in a bit of a quandary: more terrain is feeling safe to travel upon, but the chance of triggering a large deadly avalanche remains in isolated places. This last part is what keeps us in the moderate danger rating. Triggering a larger dangerous avalanche is still in the cards if you travel on steep, rocky, shallower areas, or where drifting builds uneven slab depths influenced by terrain twists, turns, or bends. 

Despite several days since the last natural or human triggered avalanche, warning signs continue to rear their heads - albeit with less predictable occurrence. With how weak the various flavors of persistent grains were before being buried, treating them as suspect till proven otherwise will help reduce your avalanche risk. If decision-making around stability is too challenging or you observe non-conclusive snowpack evaluations, there’s plenty of excellent riding conditions on lower-angled terrain away from bigger avalanche paths to wait for another day.

As you move closer to the treeline and above, you may start to encounter more wind-drifted, slabby conditions and where terrain management may need adjusting. Lens-shaped pillows, fresh cornice growth, and the snow surface becoming harder and hollow sounding should clue you into the more worrisome places.

The avalanche danger will increase over the weekend as a warm, wet storm delivers a combination of dense storm snow and moderate rainfall to the snowpack. Precipitation - whether in the frozen or liquid form - will quickly stress stubborn, weak snow grains and softer, low-density snow in the upper snowpack and increase the chance to trigger a slide, and some may fail naturally. Given the lingering uncertainty around the spatial sensitivity of buried weak layers and multiple contributing weather factors, it’s best to maintain a conservative travel approach if not avoiding steeper terrain altogether.

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