Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

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

In sintesi

On Wednesday, you can trigger avalanches in freshly fallen snow on slopes 35 degrees and steeper. The most dangerous slopes will be near and above treeline where avalanches may be bigger and easier to trigger. Watch for recent avalanches or test slopes that slide easily as signs that you should stick to lower-angle terrain.

Problemi valanghivi

  • Storm Slabs

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

    Storm slab avalanches will be the largest and most dangerous near and above treeline. You could trigger avalanches within the new snow or at the interface of old and new snow. Storm slabs will be growing throughout the day. If you find unstable snow, stick to lower-angle slopes under 35 degrees. Avoid traveling on convex roll-overs and steep, unsupported slopes. Use extra caution in and around terrain traps, where any avalanche could have serious consequences.

    1- 1.5 feet of snow could accumulate by Wednesday evening. Above treeline you may encounter drifting and stiffer, wind-affected snow. Cracking in the snow, sculpted drifts, and stiff feeling snow are all indicators. Avoid leeward wind-loaded slopes over 35 degrees. On any slope, you can use quick snow pits and small, inconsequential test slopes to check if the snow slides easily. Look for a potential poor bond at the new/old interface, where observers reported some weak old snow surfaces including surface hoar. 

    (12/28/2020) An example of a snowboarder-triggered avalanche in recent snow on Shuksan Arm near Mt Baker ski area (NE, 5400ft). Photo: Colin Wiseman

Avalanche Discussion

A stout crust formed on December 21st and is now 2 feet or more below the surface. There have been reports of weak snow grains immediately above the crust. Keep an eye on this interface as the snow adds up. Near Mt Baker, backcountry riders have recently triggered avalanches on the crust and it's not out of the question in this zone. Otherwise, the crust is stabilizing the lower snowpack including the weak layer associated with the widespread natural avalanche cycle on the 19th.

This thin layer, which at one time was small facets buried on December 12th, is now about 3 feet below the surface and can be found just above a layer of frozen melt forms or a crust. These old facets (now mostly seen as softer rounded grains) were responsible for the persistent slab avalanche cycle and the layer is now unreactive. In isolated areas, you may still find the Dec 12th layer showing up in snowpack tests, but very large and destructive avalanches on this layer are unlikely.

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources. Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

Regioni coperte