Bulletin d’avalanche

Mt Hood

Northwest Avalanche Center
Voir sur la carte

Danger d’avalanche

Fri
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
Open full map
Périmé — ce bulletin a expiré 8 months ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Rain on previously dry snow will destabilize snow surfaces, particularly Thursday afternoon. You're risk of triggering a wet loose avalanche increeases on shaded slopes lacking a crust. 

Problèmes avalancheux

  • Loose Wet

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

    Settled, scoured, wind-compacted, or crusted snow exists on most aspects of Mt Hood. Therefore we don't think that 1/4 inch of rain on snow will cause widespread wet loose activity. It is more likely to destabilize snow surfaces in sheltered areas that avoided a sun crust. This setup primarily exists on W-NW-N-NE-E aspects. We expect cloudcover to limit snow surface warming until rain falls on snow. Once this shift in weather occurs, dial back your terrain selection. Generally small human-triggered or natural avalanches are possible. Therefore, watch for steep slopes that may be above you. While snow could destabilize on shaded aspects at lower elevations, snowpacks are unlikely to produce avalanches that will harm you.

    (3/13/2022)

    Example: A small loose wet avalanche in previously dry snow.

    Photo: Ron Martin

Avalanche Discussion

Clouds, rain, and highest elevation snow will increase throughout the day on Thursday. Avalanche danger may be minimal to start the day, but could increase quickly if a rain band moves over the area. Make sure you don't let yourself get caught without a safe exit plan if conditions deteriorate.

If you ascend above the rain/snow line or the rain/snow line is lower than forecast, wind slabs will start to form in your terrain. Use typical precautions, stearing around wind-loaded pockets 6" or deeper that form on the lee side of ridgelines. 

Snowfall accompanied strong to extreme winds 12/26 and 12/27. Mt Hood pro patrol triggered large slabs and found a firm slab overlying faceted snow above the 12/24 crust. The faceted snow has been healing along with slab reactivity and we don't expect these stubborn slabs to maintain reactivity moving forward.

Temperatures have been unseasonably mild on Mt Hood with temperatures reaching the 40s at 5500 and 6500 ft on Wednesday. This has formed crusts on most steeper SW-S-SE aspects, with wafer thin crusts likely observed on a more W aspect. Wet snow surfaces were found on steep south-facing slopes, but sun-induced wet loose activity was minimal. Rimed, variable sun crusts, dry snow, and wind-affected snow surfaces could be found at upper elevations on Mt Hood on Wednesday.

Despite recent accumulations, the snowpack remains thin by late December standards and snow depths increase markedly above 6,000 ft. Keep an eye out for shallow coverage down low, scoured west-facing aspects, or thinly bridged crevasses in alpine terrain. 

 

Régions couvertes