Bulletin d’avalanche

East Slopes Central

Northwest Avalanche Center
Voir sur la carte

Danger d’avalanche

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

Points saillants

The deep storm snow is settling out, but still warrants caution at upper elevations. Snow showers may add to the potential for small loose snow avalanches on Saturday. Increasing ridgeline winds should quickly build new wind slabs later in the day. 

Problèmes avalancheux

  • Wind Slabs

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

    Wind slabs will be one of the more likely avalanche problems to injure you on Saturday. Expect westerly winds to pick up at ridgelines and begin transporting snow later in the day. Slabs could become reactive quickly in exposed locations. You can still find areas of thick drifts in upper elevation terrain from the past week of stormy weather.  Most of these slabs are likely to be small, but there may be lingering potential to trigger very large avalanches if they fail on an old crust from early April. This might be in high, north facing terrain. Look to minimize your chances of triggering a slab by sticking to wind-sheltered areas,  and moderate angled supported terrain.  If you see warning signs like shooting cracks, active wind transport, or hear whumphing collapses, stick to slopes less than 35 degrees. 

    There is a significant amount of new snow in many areas in the East Central from this past week, and we have minimal information from alpine terrain nearer the crest. Travel cautiously when heading into the higher mountains.

    (4/14/2022)

    Wind textured and drifted snow on Icicle Ridge above Leavenworth.

    Photo: Matt Primomo

  • Loose Dry

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    Low-density new snow could slide easily on very steep slopes, especially at times of heavier snowfall, and during the afternoon on slopes that receive sun. Stay alert to changing conditions and expect slopes well over 35 degrees to 'sluff' easily. Use small test slopes to check how the snow is behaving. Use extra caution near slopes with terrain traps like trees, gullies, or rocks.

    If you observe snow surface becoming heavy or damp, consider moving to more shaded aspects or slopes less than 35 degrees. The surface of east-south-west aspects could quickly become warm and wet as the daytime warms up. Even 10 minutes of sun could be enough to trigger natural loose wet avalanches. Again, make sure to consider what is above you during periods of sustained sunshine or warm afternoon temperatures.

    (4/14/2022)

    Small loose wet avalanches ran soon after the sun came out on Thursday. This slide was above US 97 near Blewett Pass.

    Photo: Katie Warren

Avalanche Discussion

Expect another round of light to moderate snow followed by increasing winds later on Saturday. Snow conditions have generally been excellent, deep powder. You could expect to find thin sun crusts from Friday on slopes that receive sun. On Friday, clouds increased and by mid-morning many areas received a short period of heavy graupel snow showers. Mission Ridge reported triggering small wind slabs and loose avalanches with control work. Forecaster Katie Warren found 3ft of new snow at Tronsen Head, and the new snow was generally right-side up and well bonded to the early April crust. Many areas recorded 11" to 16" in the East Central by mid-morning on Thursday. The heavy snowfall spurred a round of large natural loose avalanches in very steep terrain (see photo of the large loose avalanche in Power Creek in Tumwater Canyon below). With the tricky springtime weather forecasts, it'll be best to take a dynamic approach to your day. If you find that it is snowing heavily, expect instability to rise quickly, and make adjustments to your route to fit the observed danger. 

The recent storm snow is up to about 4ft at upper elevations of Mission Ridge, and similar amounts at Blewett Pass with some drifts well over 7ft deep. We lack much information from other locations in the East Central, but ranges from Entiat to the Enchantments to the Teanaway likely have multiple feet of new snow over a thicker crust from early April as well.  On Wednesday, an observer reported a small natural windslab near Blewett Pass, and I also observed what appeared to be a small wind slab from an exposed feature at 6,500ft near Mission Ridge that day. Here is my observation from that day. If you make it out, please help us finish the season strong and submit an observation to the platform. Thanks!

Régions couvertes