Bollettino valanghe

East Slopes North

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
Open full map
Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

You can still trigger dangerous and surprising slab avalanches.  Avoid being on or under large, steep slopes, especially where the wind has formed drifts of recent snow. Keep choosing lower-angled terrain and minimizing your exposure to avalanche paths. 

Problemi valanghivi

  • Wind Slabs

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

    Choose lower-angled or windward slopes to avoid triggering these avalanches. While you can keep from triggering these smaller avalanches by steering around the drifts, you could trigger much more deadly persistent slab avalanches on many of the same slopes. Recently fallen and transported snow added stress to deeper weak layers. To stay safe, you will need to avoid both the wind slab and persistent slab avalanches.

    Numerous wind slab avalanches were triggered over the weekend. Moderate to strong westerly winds formed shallow slabs on leeward sides of ridges Friday-Saturday and again on Monday. 

    (2/5/2022)

    Westerly winds transported snow and formed wind slabs and cornices on Cutthroat Pass on Feb 5th.

    Photo: Drew Lovell

  • Persistent Slabs

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

    You can trigger dangerous persistent slab avalanches on slopes 35 degrees and steeper. You may be able to trigger these avalanches from far away or from overhead slopes. Avoid being on or under suspect slopes, especially where you see recent wind drifts. Put a large buffer of terrain between where you travel and large start zones. Minimize your exposure to large avalanche paths and look for safe locations to stop or regroup.

    "Red flag" signs of the danger include whumphing collapses, cracks shooting through the snow, and tests that propagate or fail suddenly. Look for the late-January weak layer 1.5-2 feet below the surface as a combination of weak, sugar-like facets and crusts. The weakest snow may be sandwiched between two crusts. Below 5,600ft, you may find buried surface hoar at this interface. We have good information about the problem near Washington Pass, Rainy Pass and Hart's Pass. We believe that the problem exists elsewhere in the zone, though we're uncertain. 

    (2/4/2022)

    A party remotely triggered avalanche (R4-D1.5) from 600 feet away in the Hart's Pass area. This avalanche sympathetically triggered another small slide nearby. East, 6,800ft.

    Photo: Josh Cole

Avalanche Discussion

Once again, strong west to southwests winds transported snow on Monday at upper elevations, further adding stress to the already touchy snowpack. You can manage the risk of overlapping avalanche problems by limiting your exposure to avalanche terrain- stick to lower-angled slopes and simpler terrain. On Sunday, guides near Hart's Pass reported numerous natural persistent slab avalanches on leeward sides of ridges, large collapses, (traveling up to 600ft), and tests showing propagation on the late January weak layer on northwest and east aspects near treeline. For the past week, observers have reported similar signs of instability and tests showing the potential for triggering slides on the late January facet/crust layer throughout the Highway 20 corridor including in the Hairpin Valley and on Kangaroo Ridge. 

Avalanche observations: On Saturday, a party of backcountry travelers triggered a 3-foot deep slab avalanche near Maple Pass on an east aspect at 6,600ft. Three of the four riders were involved with the avalanche and one was carried 400 vertical feet, but unharmed. See the photo below.  Elsewhere, professionals intentionally triggered small wind slab avalanches on east through south aspects above treeline. Observers reported natural wind slab avalanches in the Hairpin Valley and on an east aspect, near treeline on Cutthroat peak. On Friday, observers remotely triggered a slab avalanche (size R4-D1.5) from approximately 600ft away on an east aspect near 6,800ft in the Hart's Pass areas. This slide triggered another (sympathetic) small slab avalanche. The neighboring West North zone was also active over the weekend, with backcountry travelers triggering both wind slabs and large persistent slab avalanches (see photo below) on the same late-January weak layer that exists in this zone. 

Regioni coperte