Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

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

In sintesi

Continued winds and light snow will form shallow slabs where you could trigger an avalanche. Steer around steep terrain where you identify deep pillow-like drifts or stiff textured snow. A low likelihood but high consequence chance of triggering a much larger avalanche on weak snow 2-4ft deep also exists, so consider this potential if you are stepping into steep, northern terrain at upper elevations.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    At upper elevations, continued winds and some light new snow may form shallow fresh wind slabs where you could trigger an avalanche. Older wind slabs that formed on Sunday and Monday could still be lingering and might be covered by a dusting of fresh snow. Slopes below ridgelines and the base of cliffs are likely spots for wind slabs to form. Look for textured surfaces or stiff, hollow-sounding snow to identify wind slab locations. You can also use quick hand pits, your probe, or poles to feel for stiffer snow over softer snow. If you see shooting cracks in wind-stiffened snow, this is a sign to choose low-angle terrain. 

    Cornice falls are common this time of year and are a hazard on their own, but they can also trigger slab avalanches on the slopes below. Don't linger for long beneath these monsters. We expect most of these avalanches to be small, but there is potential for these avalanches to step down into deeper layers and become large. 

    (2/15/2024)

    An example of cracking in wind drifted snow. 

    Photo: Katie Warren

  • Persistent Slabs

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

    While we think the potential for widely propagating persistent slab avalanches is isolated, it can still be challenging to identify which slopes have the potential for avalanches on these weak layers. While the likelihood is low, the consequences of triggering a 2-4ft thick avalanche could be dire. You'll want to consider these risks before jumping into steep north-facing terrain at upper elevations. If you travel in this terrain, choose well-supported slopes and avoid likely trigger points like shallow spots near rocks and trees or steep convex rollovers. 

    We have observed a preserved weak snowpack structure of faceted snow over the Early February Crust on some northern aspects above about 5500ft. Stability test results are inconsistent, and this layer has had little avalanche activity since the warm-up. We can't write this tricky problem off yet, but we're gaining confidence that it's much more difficult to trigger. 

    These avalanches can surprise you by propagating widely or being triggered from a distance. You may or may not receive signs of instability before triggering this type of avalanche. The best way to reduce your risk of triggering persistent slabs is by avoiding leeward sides of ridges and steep, rocky, complex start zones on the north side of the compass. 

    (3/24/2024)

    A recent very large avalanche near Mt. Daniel. We suspect this avalanche ran between 3/22 and 3/24 on a deeply buried weak layer. 

    Photo: Andy Harrington

Avalanche Discussion

A cloudy morning with light rain and snow showers should give way to a sunnier and warmer afternoon. Expect more precipitation closer to the Cascade crest, and a convergence zone may set up along the I-90 corridor, bringing more precipitation to the Salmon La Sac area. As temperatures warm in the afternoon and the sun comes out, you may see some small, wet loose avalanches or rollerballs on steep, sunny slopes. 

 It is early spring, and the dynamic spring weather brings dynamic avalanche conditions. New snow concerns like wind and storm slabs can quickly become wet snow problems by the afternoon. Make frequent observations, and be prepared for rapidly changing conditions and snow stability. 

Over the weekend, an NWAC forecaster in the Salmon La Sac area found 8-12" of new snow and some shallow wind slabs. They also reported plenty of melt-freeze crusts and recent wet loose avalanche activity from the sunny weekend. North-facing aspects above about 6000ft still held soft, dry snow surfaces. They saw a widely propagating avalanche near Mt. Daniel, which may have failed on a persistent weak layer between 3/22 and 3/24. The Mission Ridge Pro Patrol reported weak snow and propagating test results on the EFC on shaded aspects above 6000 ft. They found this weak layer about 2-3 ft deep. Check out the video in the gallery for more information. With this uncertainty, the best strategy is to widen your margins. 

Lower elevations are melting out quickly, and you may experience challenging travel conditions below 4000ft, particularly on southern slopes. 

Observations have been sparse. Help create a more accurate forecast by submitting your public observations here. 

Regioni coperte