Bulletin d’avalanche

Silver Valley & Bitterroot Mountains

Idaho Panhandle Avalanche Center
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Danger d’avalanche

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

Points saillants

Expect different avalanche problems at different aspects/elevations today. New, heavy snow will create storm slabs above 5,000', while rain soaked snow at lower elevations will create loose-wet instabilities. To manage all hazards, stay clear of steep, open terrain and be aware of changing conditions.

Problèmes avalancheux

  • Storm Slabs

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

    Elevations above 5,000' have picked up about 9" of new snow in the past 24 hours. This new snow came in dense and heavy, and is sitting on top of lighter density snow. With the ingredients in place for an "upside down cake" be aware of signs of instabilities, such as shooting cracks underfoot. Winds gusts mostly in the mid to upper 20's coming out of the S-SW accompanied this new snowfall, which could make terrain directly below northern ridgelines more reactive today. Avoid steep, open slopes until the snowpack has had some time to settle and bond. Lower angle terrain sheltered by timber on the northern side of the compass will have the safest and best riding today. 

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1.5–2.5

    The snowpack looks and feels different as you move from aspect to aspect. On southerly aspects we found more suncrusts throughout the upper portion of the pack. The west and northerly aspects were deeper and stronger but also had multiple  faceted layers throughout the upper 80 cm's of the pack. The layer to keep an eye on was widespread above 4500 ft. The layer of concern is a crust from 2/19 and is about 60 cm's down in the snowpack. It's easy to identify because of the graupel and the organic debris spread across the layer. It's deep enough in the snowpack that it may be hard to trigger, but if you find the sweet spot or dig your snowmobile track deep enough, it could fail and propagate. Adding snow and rain weight to the layer yesterday and last night will only inch the layer closer to a tipping point. Big open and steep slopes that funnel into a tree wall would be areas of concern today.

  • Loose Wet

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

    Low Elevation (2000-3900 ft)- Above freezing temperatures and rain have created conditions in the snowpack susceptible to producing wet loose avalanches. Loose wet avalanches generally start at a point and fan out as they move down a slope. Cohesionless snow can move down a slope unannounced and be big enough to knock you off your feet or pile up deep enough to bury a person. Be aware in gullies, terrain traps and flat areas under steep banks such as roads or snowmobile trails. Pinwheels are good indicators of cohesionless snow.

    (3/13/2023) Photo: J Thompson

Avalanche Discussion

Suprisingly, we had the place to ourselves yesterday! Maybe because it was Monday and raining, but either way we didn't see another vehicle or soul on our journey. Izzy Davis and I snowmobiled up from Wallace into Nine Mile creek. We took the road up Nine Mile to Goose peak. Besides all the 'whoopties' on the road, the sledding conditions were pretty good. It was a wet snowpack at the bottom, but still plenty of snow for mid-March. As we moved higher in elevation the snow became drier and the rain turned to snow around 4000 ft. The snowpack above 4000 ft is still deep. We found a range of 190- 280 cm's of snow.  The snowpack is just over a 100 percent for the season, so we could have good snow conditions as we transition into spring. The spring sun can rapidly change the snow surface, so keep an eye on conditons around you and manage the terrain appropriately. 

Régions couvertes