Bollettino valanghe

Flathead Range & Glacier NP

Flathead Avalanche Center
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Pericolo valanghe

Tue
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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In sintesi

Watch for and steer around isolated slabs of wind drifted snow as you gain elevation. Although slabs are becoming more difficult to trigger, you can still find trouble in areas downwind of ridgelines and in cross-loaded gullies. Safer riding is found on slopes sheltered from the wind.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    On Saturday, a party in the Flathead Range triggered a small 8-inch wind slab at around 6000 feet. Yesterday, blase found unreactive slabs but observed gusty winds and moderate transport at upper elevations. Although slabs are gaining strength with mild weather conditions, I’ll still avoid obvious wind-loaded areas today: below corniced ridgelines, cross-loaded gullies, and areas with a textured surface. Look for more enjoyable and safer riding on slopes not affected by the wind.

    (1/21/2022)

    Fresh wind slabs were 10-18 inches thick on leeward slopes in John F. Stevens Canyon. These cracked under the weight of a skier.

    Photo: Adam Clark

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    2–3

    Weak snow near the ground failed in a handful of large avalanches initiated by a wet, warm storm on January 12. Although unlikely, it is not impossible to collapse one of these weak layers causing a large avalanche. If your decisions take you into steep, avalanche-prone terrain, hedge your bets on planar slopes with uniform snow coverage.

    (1/16/2022)

    FAC staff investigated the aftermath of the January 11/12 avalanche cycle in Rescue Creek.

    Photo: Cam Johnson

Avalanche Discussion

Over the weekend, we received observations of quality riding in areas sheltered from westerly winds. Riders noted thin wind slabs on leeward aspects and hard, textured surfaces on windward aspects. Most slabs show signs that they are trending towards unreactive (observation), with one exception of a triggered wind slab in the Flathead Range on Saturday (observation). This slab was small but a sign that triggering an avalanche is possible on leeward-facing slopes. We expect slabs to be thicker and more dangerous in the larger fetches of the Flathead Range and Glacier National Park. Hedge your bets on slopes sheltered from the wind with clean runouts.

Today, a quick-hitting cold front will make its way into our forecast area. Unfortunately, this system does not bring any noteworthy moisture. A trace to two inches of snow may fall with light to moderate wind speeds. With a relatively benign weather forecast, expect similar conditions to those observed this past weekend.

You will notice we listed Deep Persistent Slab as a problem. This is a low-likelihood, high consequence hazard. Large and very large natural avalanches released during last week's warm, wet storm. These avalanches failed near the ground, taking out both new and old snow. Though these weak layers continue to gain strength under mild weather conditions, it is best to steer around likely trigger points, such as rocky, complex-looking start zones and convex rollovers.

Regioni coperte