Bollettino valanghe

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Pericolo valanghe

Mon
Alta quota
1 · Debole
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 7 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Thanks to a lack of snowfall, avalanches are unlikely and most slopes are free of avalanche-related hazards.  Be on the lookout for areas where hard wind-drifts are sitting on weak, sugary snow. This scenario is most likely in upper elevation terrain that is exposed to the wind. Increasing wind speeds today may build isolated but touchy slabs in upper elevation terrain.

Problemi valanghivi

  • Persistent Slabs

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

    I skied in upper elevation terrain just east of this zone yesterday and found a very thin and weak snowpack. However, just a few inches of snow have fallen here in the past two weeks and most slopes lack a slab on top of this weak snow. The last reported avalanche in this zone occurred over 2 weeks ago when ski patrollers at Bald Mountain triggered an avalanche during mitigation work before opening the ski area. The slide failed on a wind-loaded slope harboring weak, sugary, faceted snow in the lower part of the snowpack.

    This exact snowpack scenario—hard, wind-drifted snow overlying weak, faceted snow—is where it may remain possible to trigger a slide. While triggering a slab avalanche is unlikely, I'd still pay attention in very steep, wind-loaded terrain, especially at elevations over about 9000'.

    ADDITIONAL DISCUSSIONIncreasing wind speeds today may pick up the faceted snow that formed on the snow surface this week and build isolated slabs in exposed, upper elevation terrain. While small, encountering one of these slabs in very steep and rocky terrain could have high consequences. These slabs will increase in distribution and size as the wind blows.

Avalanche Discussion

The weather pattern for our neck of the woods has been fairly stable for the month of February. A stubborn ridge of high pressure docked along the west coast has forced moisture to our north and kept things high and dry here in central Idaho. But even though the weather has stagnated, the snowpack never sleeps. Solid materials (snow) near their melting point are in a constant state of change. If you've been out this week for a few days in a row you've probably noticed some of these changes. Maybe the skiing actually improved in your favorite powder stash as the snow surface weakened and faceted. These facets can make for some good riding conditions ("recycled powder"), but they also make for reactive weak layers.

Today, a short-lived flattening of the ridge will allow for a little moisture to squeak into central Idaho. Ahead of this moisture, we should see an uptick in wind speeds for the first time since last weekend's storm. In our northern forecast zones, a good bit of unconsolidated snow (the remnants from that storm) can be found, particularly on shaded slopes. Our southern areas received very little snowfall during this storm, but the snow has faceted significantly, leaving a layer of weak snow resting on the surface. Across our forecast zones, today's increasing wind speeds will be picking up whatever loose snow it can find and transporting it. Near features that slow the wind down and force it to drop the load that it is carrying, such as ridgelines and mid-slope features like ribs and gullies, fresh slabs will build. These slabs will be much thicker and touchier in our northern areas because there is more snow available for transport, but even down south we may see some isolated wind slabs building. Across the region, these slabs will be deposited on the weak snow surface that formed this week.  

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