Bollettino valanghe

West Slopes North

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Fri
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
Open full map
Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

The snowpack is still adjusting to recent heavy loading from rain, wind, and snow. Dangerous conditions exist in the alpine where the potential for very large and destructive avalanches lingers. Non-avalanche concerns like firm and slick surfaces, open creeks, and downed trees may be your biggest hazard at lower elevations. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3

    At upper elevations, extreme winds and feet of new snow from the past 4 days created thick and reactive slabs. Cornices also grew during the storm and could fall on slopes below acting as huge triggers. Pay attention as you transition into wind affected terrain, and look and feel for sudden changes in snow surface texture and hardness. Watch for clues of instability like shooting cracks and collapses. Avoid slopes with similar characteristics to those where you see recent avalanches. Minimize exposure to overhead hazard and steer clear of cornice formations. To reduce your risk, seek out supported terrain away from wind loaded slopes 35 degrees and steeper. 

    (1/6/2021) Human caused cornice failure near Huntoon Point that fell and triggered a large avalanche (D2) on a north aspect at 5000ft.

  • Glide Cracks

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3

    Numerous glide avalanches occurred Monday-Wednesday with several inches of rain to 6000ft. The snowpack was heavily saturated and continues to drain free water lubricating the ground. Under these conditions, the entire snowpack could release in steep areas with smooth ground cover or rock slab. Glide avalanches can occur for a day or two after a rain event, even as temperatures cool and snow surfaces refreeze. They are difficult to predict, but cracks, which usually form first, are a good indicator. Watch for deep cracks in the snow in steep areas, usually with ground visible at the bottom. Stay off slopes where you see these cracks or any slopes with similar characteristics.

    (01/13/21) A very large glide avalanche and other glide cracks in northerly terrain near 4500-5000ft on Shuksan Arm. Photo: Ben Williamson

Avalanche Discussion

A hazardous atmospheric river event (observed category 3-5 AR along the WA and OR coast) delivered just over 10in of water to the North Cascades January 10-13. Not surprisingly, a widespread natural avalanche cycle occurred as a result. Numerous dry snow avalanches within new and wind drifted snow occurred at upper elevations where precipitation fell as snow. Many were large breaking 1-2ft deep, while others grew very large breaking several hundred feet wide and running thousands of vertical feet like on Mt. Shuksan's White Salmon Glacier pictured below. Wet avalanches occurred in many areas as heavy rain fell up to 6000ft, including loose wet slides and several glide avalanches. Winds were strong to extreme during the storm and peaked overnight Tuesday with gusts up to 80mph recorded at the Pan Dome weather station (5020ft). As precipitation tapered off early Wednesday, strong cooling occurred with a 10-15F degree drop in temperatures. Many areas now have a firm and frozen crust with slick and challenging travel conditions. Despite the cooling, the snowpack is still saturated below the frozen crust and draining significant water from all the rain. Snow and avalanche conditions are unusual following such a dramatic storm event like this. Continue to build in a wide margin for error as the snowpack continues to adjust. 

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