Bollettino valanghe

Stevens Pass

Jan 25 – 26, 2019
Vedi sulla mappa
Archiviato · scaduto 8 years ago

Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
Apri la mappa completa

In sintesi

The Bottom Line: The snowpack is adjusting to its heavy new load, but lack of a solid freeze is causing uncertainty with a deeper weak layer. Wear your best thinking cap, and travel with care through avalanche country. 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    3
    A layer of surface hoar, buried on January 17th, should be 2 to 3 feet down from the surface. Lots of uncertainty exists at the moment with how this layer may react to people traveling over the top of it. We do know that persistent weak layers often become more reactive after a big loading event such this. As recently as the 23rd, observers reported a very loud collapse at 4800ft near Grace Lakes. The collapse sympathetically triggered another collapse, heard as a WHUMPH! You're most likely to trigger it in wind-sheltered, shaded, and open terrain, possibly up to ridges, and east of the Cascade Crest. Instability has been found on this layer with snowpack tests or whumphs at Grace Lakes, Skyline, Yodelin, LichtenbergMountain, Smithbrook, and Jove Peak. Below 4800ft, the snow surface has become wet, and water has made its way through. The snowpack is in need of a solid refreeze, but unfortunately that may not happen anytime too soon. As such, it’ll be best to treat the slopes like this layer could still fail. Small and large snowpack test can help you identify this weak layer and gather information. Lack of evidence in one profile or snowpack test shouldn't be a reason to travel in more consequential terrain.

    The size of the potential avalanches has increased with the new coat of snow. As such, any avalanche on this layer would be very large and surprising. Don't travel up underneath big slopes, and consider this layer before venturing onto slopes steeper than 33 degrees. 

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2
    A substantial amount of new snow fell above 5,000ft. The snow fell cold initially, and temperatures warmed up as the snow accumulated. At upper elevations, the snow may still be dry, and deep drifts are likely to be encountered. What is this new snow sitting on? Is there strong over weak? Is the new snow cracking, or do you see recent avalanches? Storm slab instabilities should continue to bond as time goes on. Be careful of steep slope breakovers and where the snow may be drifted in by recent winds.

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2
    Loose wet avalanches may still occur on steep, sunny slopes. These could entrain heavy, wet snow, making it down to lower elevations. You will see evidence of the recent activity. Now you will need to ask yourself is the snow surface wet and heavy? If you see roller balls, watch small loose wet slides run, or notice you are sinking in past your boot top in wet snow, it's time to get off of steep slopes. 

Snow and Avalanche Discussion

Stevens Pass racked up over 2” of snow water equivalent in about 13” of snow Tuesday night and Wednesday. Snow accumulated rapidly as heavy snow fell and the temperatures warmed up, this caused a widespread natural avalanche cycle throughout the Cascades. Many large paths in the area ran including Wellington, Highway Chutes, Lichtenberg Southeast side, Arrowhead Northeast Bowl, The Swath, and likely others. These slides entrained wet snow as the debris ran through the water saturated lower elevation snowpack. It rained up to around 5,000ft, but at that elevation the crust is reported to be fairly thin.

Regioni coperte