Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

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

Even warmer temperatures Wednesday will continue our spring trend of wet loose avalanches. Freezing levels will rise to 8500ft on Wednesday, so you can expect the sun to rapidly soften slopes as it hits them.  When surfaces become wet and punchy move away from steep slopes to cooler areas where the snow remains supportable.

Problemi valanghivi

  • Loose Wet

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

    The sun progressively cooked snow surfaces more every day since Sunday, and wet loose avalanches continue to run as temperatures record a new high every day. Upper elevation northerly aspects are maintaining their wintery grasp, still holding onto cold dry snow. The sun will work around the compass E-S-W as the day progresses, and wet loose avalanches may occur on steep slopes as the sun directly shines on those aspects as the day progresses. 

    Pay attention to rapid changes in the snow surface and watch for rollerballs and avalanches on similar slopes. It's time to move to shady slopes or head home when you start noticing these indicators. Keep your return routes in mind as well - slopes you crossed safely earlier in the day may become wet, weak, and dangerous by the afternoon.  

    (4/13/2021) A wet loose avalanche which occurred Monday on a west facing slope on the approach to Mt Ann at approximately 5000ft.

  • Wind Slabs

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

    On Tuesday an observer reported finding recent wind slab avalanches up to size D1.5 on Mt Shuksan. Strong winds Monday night into Tuesday morning redistributed snow at upper elevations. You may encounter isolated wind slabs that could avalanche with the added weight of a person. Storms in the last week deposited around two feet of snow. They were showing strong interfaces with the underlying crust, and also in mid-storm interfaces, however wind slabs have since formed at upper elevations. You may find recently drifted unstable areas above treeline, primarily on north and east aspects above 5000ft. The most likely places to trigger an avalanche are on rollovers steeper than 35 degrees, and on slopes below cornices and cliff bands. Use visual clues to identify and avoid wind-loaded snow in consequential terrain. Seek out wind-sheltered slopes or terrain less than 35 degrees if you find recent avalanches, cracking, or collapsing.

    (4/13/2021) NE winds were cranking Monday night through Tuesday morning. This photo shows wind transporting snow on Mt Shuksan, taken at 9am on Tuesday before the winds backed off

Avalanche Discussion

The significant spring thaw is continuing. Warm temperatures and wet snow are prevalent in daylight hours, while clear skies will hopefully freeze snow overnight. Be aware of crusty surfaces making travel difficult before snow softens. Freezing levels are on the rise and will climb more each coming day. Plenty more slopes have yet to run with wet loose avalanches. Expect a mix of wet and dry snow avalanche problems and big variations between aspects, elevations, and time of day. 

Observers throughout the West North zone reported numerous small wet loose avalanches and a handful of small human-triggered wind slabs. Wind slabs are becoming harder to trigger, but stay alert as you climb up in elevation and transition into wind-affected terrain. Isolated large glide avalanches also occurred recently, and we will likely see more with continued warming and sun. Keep your eyes peeled for crevasse-like cracks in the snowpack and avoid travel on or below slopes where they exist. Cornices grew large throughout the winter and continue to be tested by sun and warming. Stand far back from these features along ridges, and avoid travel on slopes below.

Daily avalanche forecasts will end on Sunday April 18th.

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

Regioni coperte