Bollettino valanghe

West Slopes Central

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Fri
Alta quota
4 · Forte
Limite del bosco
4 · Forte
Sotto il limite
3 · Marcato
Open full map
Non aggiornato — questo bollettino è scaduto 6 months ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

After suspected peak natural avalanche activity Wednesday night, conditions will remain very dangerous on Thursday. If you make it into the backcountry, avoid all avalanche terrain, especially as you work your way into thicker snow higher, as natural avalanches are likely and human-triggered avalanches are very likely.

Problemi valanghivi

  • Storm Slabs

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

    A recipe for very dangerous avalanche conditions exists right now, between feet of new snow, fluctuating temperatures resulting in precarious upside-down snow layers, and gale-force winds. These are all red flags, or bullseye clues, pointing us to obvious advice: avoid all avalanche terrain. Not only should you stay off steep slopes, but avoid traveling beneath avalanche paths as well. 

    Avalanches will be larger and more reactive in wind-affected, areas. Likewise, as you climb higher, expect a more reactive snowpack, and avalanches that could be nearing very large in size. At lower elevations, there is a little less new snow, not as much wind-effect, and less of an old bed surface. You can still trigger avalanches, and there could be naturals, but they'll probably be a little smaller and not as sensitive.

    Example photo: Large, dangerous avalanches are expected to fail either naturally or with a human trigger, on steep slopes. 

Avalanche Discussion

Lots of snow, fluctuating temperatures, including rain down low, plus gale-force winds are the story of the last 24 hours. This isn't your average PNW snow storm - a thick layer of light, fluffy snow about 18-24" thick fell across the zone, before much heavier snow fell on top, resulting in an unstable, upside-down snowpack, plus wind-effect. Cooling temperatures, over another foot of snow Wednesday night, with more gale force wind will likely result in peak avalanche activity Wednesday night. On Thursday, we could receive almost another foot of snow, and winds will "back off" to moderate. It will probably take a while for the thick layer of low density snow to adjust to all the snow on top. 

This storm produced about 4 inches of water since March 8, which could translate to 4 feet of highly wind-affected snow at mid and upper elevations. Drifts could be enormous, and this almost feels like the start of winter now that it's March. Forecasters in neighboring zones on Wednesday all found a slow start to the day, with avalanche activity quickly ramping up in the afternoon. Small and large soft slab avalanches were easily triggered, although natural avalanches weren't reported yet. Many of these failures were in a mid-storm layer, like you can see in the media gallery. 

Regioni coperte