Bollettino valanghe

West Slopes South

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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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

A weeklong warming trend will continue on Wednesday, potentially destabilizing the snow surface and producing wet avalanches. The nice springtime weather will have to overcome some gusty winds to reach this point, so use the snow surface as you guide to determine if the time has come to head toward shady slopes.

Problemi valanghivi

  • Loose Wet

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

    Take a moment to step out of your mode of travel and check how deeply you are sinking into the snow on sunny slopes Wednesday. If you find that you are sinking past your ankle, the warm weather has overcome the cool breeze and you should start to think about wet avalanches. Other visual clues like fresh rollerballs or recent avalanches with fan-shaped debris can help you determine that the snow surface has destabilized and it is time to head toward shady slopes to mitigate your hazard. Wet avalanches are complex and often intermingled; wet loose, wet slab, or cornice collapses could all occur on sunny slopes, entrain significant snow, and possibly grow large while traveling long distances toward lower elevations. Choose safe travel routes and be aware of your overhead hazard at all times. 

    (4/4/2021) Take the time to step off your mode of travel and see how deeply you are sinking into the moist snow. If you're sinking in deeper than your ankle, you should start to suspect wet avalanches. [Boot Pen: 40cm N ~4600']

  • Wind Slabs

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

    It's been pretty windy in the West South, and those winds should continue Tuesday night and into the day on Wednesday. Cold dry snow still exists on shady slopes that don’t see direct sunshine, and this snow may have been blown around to create some shallow Wind Slabs. Take a look for these slabs as you ascend in elevation near rocky features such as the sides of gullies or the base of cliffs, or on leeward slopes near ridgelines. Due to winds coming predominantly from the East, slabs may have formed in areas you are not typically used to finding them, or cross-loaded features. Keep a keen eye out for textured snow surfaces or fresh drifts behind objects such as trees and rocks to help you identify wind-loaded features to steer around.

    (4/11/2021) Wind textured surfaces, cornices, and smooth pillow-like piles of snow were observed near Crystal Mountain on 4/11 and can help you to identify wind-loaded slopes.

Avalanche Discussion

The winds were ripping near the crest on Tuesday, with NWAC's station at Crystal Mountain recording a gust of 96 mph! The wind did downtrend during the daylight hours and may have muted the ability for wet avalanches to be more widespread in some areas. Expect similar conditions to develop on Wednesday, but with even warmer temperatures and a windy day that could downtrend in the afternoon. 

Many aspects have been receiving direct sunshine and should be going through a melt-freeze cycle due to cool nights and warm sunny days, creating a firm surface crust with cold snow below it. Tuesday night may be the last night this week for us to get a strong overnight freeze, after which conditions could potentially become much more unstable as we head toward the weekend. On shady slopes, cold dry snow should still exist on the surface, creating an aspect-dependent snowpack. As the snow surface softens throughout the day on sunny slopes, expect a continuation of the springtime shedding cycle that started on Sunday and is expected to produce wet avalanches, snow falling off trees or rocks, glide avalanches, and cornice collapses. On the shady side of the dial, keep an eye on new and recent layers in the snowpack that could be points of failure for dry avalanches.

Barring some unforeseen development, this is my last avalanche forecast for the season. I want to take a minute to say thanks to everyone for a great year. To all who submitted public observations, I really appreciate it, thank you. I know it may seem like we are always pleading with you to submit more, but they genuinely do help us as forecasters and make the product better. I encourage you to continue to submit them throughout the spring to keep us and the community in touch with what is going on with the springtime melt-out. Just because we are off the clock does not mean that we are checked out. Have a safe and fun offseason and I’ll see you next year!

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.

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