Bollettino valanghe

Mt Hood

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
Open full map
Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Winds, cooling temperates, and snowfall will build small slabs on lee slopes at upper elevations. You can trigger a slab anywhere 6" or more of snow has piled up on top of a crust. Rainfall at lower elevations will create slushy snow surfaces and shallow loose avalanches that can harm you if it pushes you into a gully, a creek, or over a cliff.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Snow levels will drop throughout the day with moderate precipitation. Slabs will develop during the morning hours, increasing in size, extent, and reactivity throughout the day. The new snow should bury a refreezing or refrozen crust on all aspects. Use this crust to determine how much snow has fallen. Anticipate deeper drifts on wind-loaded aspects. Use signs of active transport such as actively blowing snow, fresh, sharp cornices, and cracking snow surfaces to help you steer around the developing hazard. While we expect this to remain an above treeline problem, if cooling and snowfall accumulate sufficiently to lower elevations, this problem could creep into near treeline terrain. If a problem exists in your terrain, travel safely along ridges or windward slopes, avoiding lee slopes steeper than 35 degrees. 

    Example: Shallow wind slab on steep wind-loaded slope below ridgelines.

    Photo: Matt Lubar- Baker Mtn Guides

  • Loose Wet

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

    Following days of warm temperatures, the lower elevation upper snowpack has mostly adjusted to a saturated state. However, on very steep slopes or extreme terrain features, you can still produce a small avalanche.  You're more likely to trigger a wet loose avalanche during periods of heavy rainfall. Rain on snow at lower elevations may produce a layer of slushy snow up to 8" deep, but a crust formed 1/6 should restrict the depth from entraining more than this surface layer. If you find unconsolidated wet snow layers more than 6" deep, steer around extreme terrain features and steep slopes above terrain traps such as gullies, narrow canyons, and cliffs where even a small avalanche will be consequential.

    (1/7/2022)

    Small natural wet loose avalanche (D1) along Hwy 35 (NE aspect, 3100ft)

    Photo: Andrew Kiefer

Avalanche Discussion

Temperatures were exceedingly mild on Wednesday with the mercury rising to 40F at 6500 ft. Mt. Hood Meadows reported no new signs of avalanche activity. Winds kept northerly aspects cool, while solar radiation softened snow surfaces on more southerly aspects. Light rain fell up to 6000 ft on Tuesday with minor rollerball activity reported. The last snow fell on Monday with around 2" of accumulation before snow changed to rain up to around 6000 ft. Small wet avalanches were confined to the new snow.  

Mild temperatures, snowpack consolidation, and crusts forming likely even on parts of the upper mountain has lowered the avalanche danger following the major loading event January 2-7. This event brought 5-7+ feet of snow and caused a widespread natural avalanche cycle. The most notable avalanche from the cycle  was a very large natural on the upper Newton Clark Glacier. The crown was easily 10ft deep in places and debris reported ran 4500ft down into Newton Canyon. A public observation highlights this avalanche, in addition to another notable avalanche near treeline. We don't expect further very large avalanche activity from the upper mountain at this time.

Warming during the last storm cycle formed a crust that was buried 1/6. A foot or less of snow accumulated on top of this crust before the storm cycle ended. Despite continued mild temperatures Wednesday night, fresh crusts are expected to form on all aspects and at most elevations by Thursday morning. When you head out in the field, you're likely to find rain rills at lower elevations; above treeline you might find a mix of surface crusts on wind-exposed aspects and building wind drifts; mid elevations should be transitional as snow accumulates further down the mountain.

Regioni coperte