Boletín de aludes

East Slopes South

Northwest Avalanche Center
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Peligro de aludes

Sat
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 2 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Triggering a large avalanche breaking in weak layers 2-4 feet below the surface remains a concerning possibility. Feedback like shooting cracks or snowpack collapses may not always be obvious. Your safest option is to limit yourself to low slope angles without avalanche terrain overhead. 

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    2–3

    Weak layers 2-4 ft below the snow surface have been responsible for numerous large avalanches recently. This persistent slab problem is becoming harder to trigger with time, but the resulting avalanche will certainly be large enough to kill you. The recipe for an avalanche exists on most middle and upper-elevation slopes. The Early February Crust (EFC) harbors weak, faceted snow and is now buried underneath a dense 2-4 foot thick slab. This pairing is capable of producing large, destructive avalanches. 

    This serious weak layer of concern requires patience and strict management. These slabs can trigger in surprising ways. You can trigger them from flat or low-angle terrain long distances away from steep slopes, and they can break far above you. Before triggering an avalanche of this type, you may or may not receive any direct signs of instability. Therefore, your best strategy to avoid triggering a large, unsurvivable avalanche will be to avoid travel on or below slopes greater than 30 degrees. 

    (3/7/2024)

    You can still trigger avalanches like this on Friday. 

    An older snowmobile triggered avalanche in the Blewett Pass area, likely from 3/4 or 3/5. We suspect this avalanche failed on the facets over the Early February Crust. 

    Photo: Katie Warren

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–1.5

    Winds are forecast to be transport speeds ahead of the next storm system. With significant amounts of snow available for transport, look for slab formation to occur on leeward slopes. You may find new or recently drifted slabs on the downwind sides ridgelines, near the breakover of exposed features, and beneath rock and cliff bands. Hollow sounding snow or shooting cracks under your feet or sled are signs that you found an unstable wind slab. Even a relatively small wind slab avalanche breaking in the upper snowpack may be enough to step down to persistent weak layers near the EFC, creating a much larger avalanche. 

Avalanche Discussion

What a beautiful stretch of weather. Friday will feature similar conditions but will be more of a transition day ahead of our next system, with an uptick in SW winds and higher freezing levels than previous days. Wet loose avalanches have likely run their main course on steep solars, but you could still encounter small ones during the heat of the day.

Observers across much of the Washington Cascades, particularly the eastern slopes and the west-south, have reported numerous large avalanches failing on old snow 2-4 ft below the surface. Just as recently as Thursday, an NWAC Forecaster near White Pass observed a very large avalanche on Gilbert Peak in the Goat Rocks Wilderness ( N aspect, 7500 ft). On Wednesday, we heard about another close call with a persistent slab release to the north in the Blewett Pass area. This large avalanche occurred on an east aspect at 6000 ft. In addition to the fatal avalanche accident on Darland Mt on March 1st, another large avalanche on an adjacent slope was remotely triggered by a group of snowmobilers. This widely propagating avalanche occurred on a north aspect at 6300 ft. You can check out the observation here. NWAC forecasters visiting the accident site also reported this separate large avalanche (avalanche observation). These all likely failed on the Early February Crust. 

Despite the drop in danger, you can still trigger large avalanches that can kill you. The danger has dropped because the likelihood of triggering an avalanche gradually decreases as days pass without loading. However, it's important to note that the potential size has stayed the same. Just because the color changed doesn't mean you can't trigger a large avalanche that could ruin your day and many other people's day.

 

 You can add to the avalanche forecast. Submit your observation here.

 

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