Bollettino valanghe

Banner Summit

Sawtooth Avalanche Center
Vedi sulla mappa

Pericolo valanghe

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

In sintesi

The avalanche danger will rise to CONSIDERABLE as the day warms and the snow becomes wet. Wet snow avalanches will be easy to trigger and will release naturally in steep, rocky terrain receiving direct sun. These slides can become large and destructive. Avalanches failing on layers of weak snow in the upper few feet of the snowpack are less likely but would be unsurvivable.

Problemi valanghivi

  • Loose Wet

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

    Mountain temperatures start just a few degrees below freezing (3-day temperature graph in media gallery below). Today will be another 5-8 degrees F warmer than yesterday. You'll find widespread crusts at the snow surface this morning, but these will break down quickly as the sun returns and temperatures spike. Wet snow avalanches involving the most recent snow will become easy to trigger and will release naturally throughout the day. Many of these slides will be small, but they can become large and destructive in steep, open terrain and in gullies and couloirs that channel the flowing debris.

    The wet snow avalanches we have seen thus far have been small and predictable. As temperatures continue to climb, overnight freezes weaken, and melt-water works its way to weak layers deeper in the snowpack, the possibility for wet slab avalanches comes to the table. These beasts are unpredictable and will not be small.

  • Persistent Slabs

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

    Weak layers buried underneath the settled snow that fell in March have gone into a state of dormancy. They haven't gone away, they have just become harder to trigger. If you dig down you'll find crusts with facets here on sunny slopes, and facets without crusts on shaded slopes. Triggering an avalanche involving this snow is most likely in steep, rocky, wind-swept terrain where the snowpack is variable and you can find thinner spots in the overlying slab. 

    Thursday, just south of this zone, a group of skiers triggered a frightening avalanche in a steep, north-facing couloir (photo at right/above). It failed as they neared the top of the climb, and broke an estimated 2-4+ deep across the width of the couloir. The same weak layers responsible for this avalanche exist in this zone. Any avalanche failing on this snow will break widely and will produce destructive avalanches. The first sign of instability involving this snow will be the very large avalanche you trigger. 

    (3/14/2024)

    This large avalanche was triggered on ascent as three people booted up the final 20' to the saddle at the top. No one was caught. The avalanche broke 2-4+ feet deep on faceted snow. Sawtooth Mtns, N @ 9,900'.

Avalanche Discussion

Springtime Shed with Persistent Slab Problems

You'll experience overlapping dry snow and wet snow problems today, both of which warrant your attention. As I write this in the predawn darkness, there are no wet snow issues. A thick, icy crust exists on slopes that received sun and melted over the past two sunny days. However, mountain temperatures aren't far below freezing and the day will warm up fast, quickly bringing on wet snow problems as the crust softens. These slides will initially be small, but will get larger as the day warms and the melt deepens. Sustained S-SW winds over the past weeks formed massive, unstable cornices and packed snow into all sorts of unusual places. The mountains will be shedding this snow today and over the coming days. Failing cornices and smaller wet loose avalanches can produce large avalanches as they travel downslope. Avalanches that break down into deeper weak layers in the snowpack will be unsurvivable. 

When wet snow issues come to the table, we find ourselves heading to colder slopes. Unfortunately, we can't avoid all of our avalanche problems simply by avoiding the wet snow. Layers of weak snow are buried across our forecast area. In the northern and western mountains, these layers are deeply buried and the likelihood of triggering slides on them have decreased. However, the large, frightening slide that was triggered in a steep couloir in the Sawtoots on Thursday clearly points to the potential for these layers to make deadly avalanches. In our southern and eastern mountains, these weak layers are closer to the surface and they may be a bit easier to impact with your weight. Meltwater produced at the surface is likely to reach these layers today and in the coming days, weakening the bonds are creating the potential for wet slab avalanches. 

During the heat of the day, these dry snow and wet snow problems overlap and interact. As the day progresses, it will be harder and harder to avoid wet snow issues. Even steep, north-facing couloirs have walls that face west and east that may be receiving sun. Pay close attention to the terrain above you as well as the terrain you are moving through. And expect avalanche danger and the likelihood of triggering avalanches to change quickly. 

Today is a great day to start early and be out of the way early. Avalanche conditions will be more dangerous when you are exiting the mountains than they were on your ride in. The slopes that you comfortably traveled on and under will be more hazardous on your way home. Don't let the sun lull you into a sense of complacency, traveling through the mountains and returning home safely demands your attention today. Don't linger in runout zones below large starting zones that are receiving direct sunshine. 

Regioni coperte