Bollettino valanghe

Selkirk Mountains

Idaho Panhandle Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Thu
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
Open full map
Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Fresh snowfall and a gradual rise in temperatures over the next 24 to 48 hours may help lingering weak snow layers in the upper snowpack become more reactive. As dense storm snow stacks deeper above softer, drier snow from recent storms, it may be easier to trigger a shallow avalanche that could be the extra nudge to spark a deeper failure and produce a larger, more dangerous slide. Given the lingering uncertainty in the snowpack and multiple contributing factors, it’s best to maintain a conservative travel approach.

Problemi valanghivi

  • Persistent Slabs

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

    Weak layers - surface hoar, faceted grains, and a faceted crust - two to three feet deep are the culprit of lingering instability in the upper snowpack. Snowpack tests on slopes near treeline down to about 5,000 feet continue to produce ongoing failures in these weak grains. Well-preserved and upright surface hoar is found 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.

    (2/16/2025)

    Surface hoar feathers are still 10 to 12 mm in size below a stiffening slab. While becoming harder to impact, they still produce propagating failures in tests. Selkirk Mountains. February 16, 2025.

    Photo: Chris Bilbrey

  • Storm Slabs

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

    Dense snow accumulating above softer, drier snow will form an inverted, “upside-down” slab. This will likely increase the odds to trigger a slide in the storm snow, especially on slopes with around 6 inches or more of new snow. Approach steep and open slopes cautiously, and watch for signs of unstable snow like shooting cracks, audible whumpfing, or recent avalanches. Use small, non-consequential test slopes to evaluate the sensitivity of the new snow before blindly jumping into steeper terrain.

    (2/2/2025)

    Many crown lines like this were on north, northeast, and east-facing slopes above approx. 5,500 feet. Selkirk Mountains. February 2, 2025.

    Photo: Chris Bilbrey

Avalanche Discussion

Managing newly emerging surface problems will help you avoid the sleeping snowpack dragon deeper within. The next round of snow arrives with much warmer air. While we expect the snow line to be well below our bottom forecast elevation of 4,000 feet, snow densities will likely be notably higher than the last several storms. This will quickly form fresh cohesive slabs on the surface with potentially lesser new snow depths. 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.

As the snowpack gets exposed to much warmer air in the coming days, it will likely promote additional settling and stiffening of the upper snowpack. This could make buried surface hoar or faceted grains more reactive as increasing slab weight further stresses these weaker interfaces. While the forecast staff and public observers continue to report improving conditions, we’re not ready to write off looming concerns just yet. Triggering a 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.

Regioni coperte