Bulletin d’avalanche

East Slopes North

Northwest Avalanche Center
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Danger d’avalanche

Mon
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

The avalanche danger will be minimal in the morning and will quickly spike as temperatures warm and the sun melts the surface snow. Wet avalanches will likely occur as the day warms and they could be big enough to bury or kill you. Plan your travel to stay out from under cornices and to be off of sunny slopes before wet avalanche activity begins.

Problèmes avalancheux

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    Expect the warmest temperatures in almost 2 weeks and enough sun to maintain the threat of wet loose avalanches. You may be able to trigger avalanches and they could release naturally from overhead terrain. Avalanches could gouge into deeper layers of snow, becoming big enough to bury or kill you.

    Give yourself plenty of options of lower angle or shaded terrain. Make sure you have plenty of time to be off of steep slopes before they get warm and weak. Take note of warming and wetting at the snow surface or previously supportable crusts melting and becoming weak. If you observe signs of instability like rollerballs, pinwheels, or very small avalanches, move to more shaded or lower angle slopes.

    (4/21/2022) A natural wet loose avalanche ( size D1) in Silver Star creek. 5,600ft, NW Photo: Josh Hirshberg

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2

    Watch for falling cornices with warming throughout the day. Cornices could trigger bigger avalanches and can be big enough to be dangerous on their own. When traveling on slopes, stay well out from under cornices that could be looming above at the ridgetop. Don't linger on slopes with overhead cornices and make sure you pick safe locations to stop and regroup. If traveling on a ridge, be careful not to wander too close to the edge or onto an overhanging cornice. They frequently can break much further back than anticipated. 

    (4/21/2022) Snow blankets cornices and rock faces near and above treeline. Charon Tower, E, 8,040ft Photo: Josh Hirshberg

Avalanche Discussion

On Saturday, observers in the Silver Star drainage reported the previously cold snow on northerly aspects near and above treeline was quickly warming. Rock faces were shedding snow, (see photo below) and slopes above treeline had lightly wind-affected surfaces. It's likely that in more sun-exposed terrain, wet avalanches may have occured. On Thursday, I found a wide range of conditions, also in Silver Star from dry ground on low elevation, south-facing slopes to cold, winter-like snowpack on north-facing slopes in the alpine. I found 4-7" of new snow and up to 2ft of recent snow over a crust from April 8th. We saw and heard about 5 loose wet avalanches off steep, rocky west-facing slopes before noon with the warming temperatures. Some of these were large (D1.5). No wind slabs were found. Elsewhere, the wind may have formed more significant slabs.

Information and observations have been limited. The North Cascades Highway SR 20 is currently gated at Silverstar, though the road is plowed further west. Until the road opens, WSDOT allows recreational access on the North Cascades Highway near Washington Pass from Friday-Sunday. With road clearing operations underway midweek and other professional operations inactive, any observations are much appreciated.

This is NWAC’s last daily avalanche forecast for the 2021-2022 winter season. Mt Weather Forecasts will continue until May 1. Make sure to check our Spring Avalanche Statement for information and travel advice. NWAC will continue to track snow and weather conditions. Large storms and/or widespread avalanche cycles may cause us to issue special avalanche bulletins, avalanche warnings, or other spring statements to keep you informed.  You can help your backcountry community by continuing to submit observations of avalanches, snow, and pertinent weather to our site.  Have a fun and safe spring recreating in the mountains! 

Régions couvertes