Bollettino valanghe

West Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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In sintesi

A late-morning shift from winter to spring conditions plus overlapping avalanche problems will require vigilance as conditions change throughout the day.  Deep new snow will react to rapid warming and produce wet avalanches. Choose terrain with plenty of options that allow you to easily avoid avalanche terrain if necessary.

Problemi valanghivi

  • Loose Wet

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

    Despite a cold start to the day, strong sun and a rapid rise in temperature will create wet avalanche problems before the latest storm and wind slab layers even have a chance to settle out. It’s pretty simple - there is plenty of new snow and it just won’t play nice once it gets overheated. It is a sure bet we will see natural wet loose and other avalanches related to warming by the afternoon. The questions that remain for tomorrow are:

    • How many will there be? On most steep slopes or just the usual locations under cliff bands, etc?
    • How big will they be? Large (D2) or smaller (D1)?
    • Will they occur on all aspects or just those getting direct sun?

    Ultimately it going to be up to you to monitor conditions throughout the day and gauge how fast the mountains are coming unglued. Given all the unknowns, it’s probably best to play it safe and pull back to simpler terrain when you see signs of instability like rollerballs and small wet avalanches or when the snow becomes wet and saturated. 

     

     

    Wet loose avalanches in alpine terrain near the Mt. Loop last spring.

    Photo: George Coiner

  • Wind Slabs

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

    New wind and storm slab layers should be less reactive tomorrow but the quantity of new snow still requires caution. The greatest danger of triggering a slab avalanche will be on steep wind loaded slopes where slabs will be reactive for longer. As the day grows warmer all slopes could see an uptick in danger as the surface layer warms and becomes denser over colder, weaker snow below. Cornice fall and wet loose avalanches could serve as large triggers than could pull out a slab where the weight of a single person may not. 

    With all the new snow identifying areas of wind slab could more difficult than usual. The best plan for Tuesday morning will be to travel on slopes less than 35 degrees to reduce uncertainty. As the day gets warmer and the sun does its work start reducing your exposure to steep terrain overhead as well.

    (4/5/2022)

    Large slab avalanche on Huntoon Point in West North. Northeast aspect at ~5000'.

    Photo: Mike Elges

Avalanche Discussion

Skies cleared on Monday afternoon in the North Cascades and allowed observers to see the extent of natural avalanche activity from the last few days. While some slopes showed little sign of activity, storm and wind slab avalanches up to D2 were observed in near treeline areas with a greater number seen in above treeline terrain. Stevens Pass and Snoqualmie Pass stayed more socked in with clouds that limited observations of the surrounding terrain. In general, the new snow is right side up with wind loaded terrain holding more of a slab as usual. Test slopes produced mixed results today with many of them showing little cracking and propagation while a few others cracked the full depth of the storm snow. 

Freezing levels and temperatures are forecast to climb even higher on Thursday reaching 10,000' by that afternoon with high temperatures pushing 50 degrees. One of the simplest adages in the avalanche world is snow doesn't like rapid change - well, rapid change is here for the next few days. As the mountains warm even more we expect to see avalanches potentially being very large in size and running to lower elevations. Cooler conditions going into the weekend should sharply reduce the danger from wet avalanches. 

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