Bulletin d’avalanche

Snoqualmie Pass

Northwest Avalanche Center
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Danger d’avalanche

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

Points saillants

Stormy weather with snow and warming temperatures will create increasingly dangerous avalanche conditions throughout the day on Friday. You could easily trigger avalanches on any steep slopes or terrain features. If you brave the weather, stick to low angle slopes to avoid being caught in an avalanche. 

Problèmes avalancheux

  • Storm Slabs

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

    Light snow overnight on Thursday will intensify on Friday, and snowfall will increase throughout the day. This warm, wet storm will override an unusually cold airmass leading to some uncertainty with precipitation type. We expect the precipitation to stay as snow. However, it wouldn't be a total surprise if we had a changeover to sleet, freezing rain, or just plain rain. Even if we receive all snow during this storm, the warming temperatures will result in sensitive storm slabs. It will be a day to avoid steep terrain and be cognisant of steep terrain features above terrain traps such as creeks, holes, or ravines where you could be buried deeply by even a small avalanche. It will be a great day to identify red flag signs of instability, such as recent avalanches or shooting cracks while traveling on low angle slopes. If you observe a change from snow to rain, know that natural avalanches may be increasingly likely, and you should also avoid traveling under steep slopes. 

Avalanche Discussion

On Thursday, we traded snowfall for frigid temperatures, down to -10 at Alpental, and gusty easterly winds. Friday, we will be headed back into more typical stormy Cascade weather with a warm, wet storm headed our way. The cold air pooled east of the Cascade Crest will hopefully maintain snowfall throughout the day on Friday, but while the storm is typical, the extremely cold air mass is not. It could end up being a strange weather day with easterly winds down low and very cold temps, mixed precipitation types, and potentially warm westerly winds up high with above freezing temperatures. If traveling in the backcountry, you should keep your senses tuned into the weather and give yourself a wide margin of safety with your terrain choices to manage this uncertainty. Recent avalanche activity from the new storm snow on 12/20 appeared to be failing at the new/old interface, but the 12/18 interface also showed up in snowpit tests. There were also isolated areas of collapsing and a fragile melt-freeze crust in many locations. Therefore, there is a possibility that avalanches on Friday could fracture lower in the snowpack at these older interfaces and be larger and more dangerous. Friday morning will still be frigid. So make sure to prepare with extra warm layers, face shields, and ensure those grip heaters are up and running.

Régions couvertes