Bollettino valanghe

Central Cascades

Central Oregon Avalanche Center
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Pericolo valanghe

Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

New wind slabs will build near treeline and above treeline on Friday. Wind slabs will be reactive and likely to trigger in terrain steeper than 30 degrees. Identify wind loaded slopes and adjust your terrain choice to avoid terrain features where significant wind loading has occured.

Problemi valanghivi

  • Wind Slabs

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

    As new snow comes in at upper elevations, the southwest winds will be moving snow to northerly and easterly slopes. Wind slabs form below ridgetops and around features that collect blowing snow.

    Montior the depth of wind drifted snow as you move through lee terrain below ridge tops. As you observe increased depth of wind loaded snow, expect resulting avalanches to become larger. 

    Ease into steeper terrain. Look for cornices at ridgetops and rough, wavy, or chalky surface texture on lee slopes to indicate where wind slabs have formed. If you encounter cracking in wind drifted snow, or observe recent avalanches, that is a good indication to stay off of slopes steeper than 30 degrees. 

  • Storm Slabs

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

    This will depend a lot on how much snow comes in Thursday night and Friday. Monitor the depth of new snow. As the day progress and we see 8-10" or more of new snow stack up, monitor how well the new is bonding to the old snow surface. Storm slabs will be more likely to trigger in steep, convex, and unsupported terrain. Use small and inconsequential test slopes to gain information on how sensitive storm slabs are to triggering.

Avalanche Discussion

A lot has happened this week. The mountains have received over 120 cm (over 4') since Monday. That was followed by warming temperatures on Wednesday afternoon bringing rain at lower elevations into Thursday morning. The bulk of the storm slab and wind slab potential from earlier in the weak has alleviated. The potential for wet avalanche problems from rain and warming has mostly subsided with decreasing temperatures in the mountains. However anybody touring in low elevations around 5500 ft and below (i.e. Santiam Pass) on Friday morning should keep wet loose and wet slab avalanches in mind until dropping snow levels turn low elevation rain into snow.

Now we are on the the next thing with new snow and wind coming in. The snow coming on Friday will like not a lot compared to earlier in the week but will bring on a new batch of wind slabs and storm slabs.

 

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