Bollettino valanghe

Central Cascades

Central Oregon Avalanche Center
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Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

High temperatures on Tuesday will be 5-8 degrees warmer than we experienced on Monday.  This warm weather and mostly sunny skies means that Wet Loose avalanches will be likely as the day progresses particularly on steep south slopes.  Time your riding to ensure fun and safe travel.  The heat from the sun and warm day will also weaken cornices which could collapse.  Minimize your exposure to cornices on these very warm days.

Problemi valanghivi

  • Loose Wet

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

    Wet Loose avalanches are our classic springtime avalanche problem.  Each night the snow refreezes and avalanche hazard can be near zero first thing in the morning.  As the sun and warm temperatures heat the snow surface they induce melting.  This melting can initially make for nice, soft riding.  As the melting extends deeper into the snowpack Wet Loose avalanches become likely and increase in size.  The direction that a slope faces is also an important consideration when planning your tour.  East slopes heat up first, and west slopes later in the day.  South slopes are the most likely to produce Wet Loose avalanches.

    On Monday, I was surprised to observe only relatively small Wet Loose avalanches above treeline.  Likely this was due in part to Moderate and variable winds over the weekend which scoured much of the soft snow off of the upper elevations.  Also there was a Moderate north wind blowing for most of Monday which helped keep things a bit cooler.

  • Cornices

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2.5

    Whenever we have sustained warm sunny weather it is a good time to steer clear of cornices.  They are always a bit unpredictable, but lots of daytime heat melts and weakens them.  Even if you are riding on shady north slopes below cornices, remember that the backs of those cornices are cooking in the sun.

Avalanche Discussion

Today was warm, and tomorrow will be warmer!  A Moderate north wind kept the higher terrain a bit cooler than it could have been but even with that I observed melting surface snow on every aspect and elevation that I toured today (between 6000 ft. and 8000 ft.).

I have removed the Persistent Slab problem.  No new avalanches for two days, accompanied by a lot of profiles and my inabaility to find any faceted snow above the upper melt-freeze crust leads me to believe that any persistent weak layer must be very isolated in nature.  If you are considering riding committing north or east slopes near treeline or above, some snowpack evaluation is warranted.  Today I found the melt-freeze crust down 35-60 cm. and in very wind loaded spots it could be deeper.  Look for compression test results that indicate faceting above the crust (pops and drops).

Regioni coperte