Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto last year. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Spring-like weather will continue on Friday, with more sun and warm temperatures. Keep track of steep terrain overhead as the day warms. Avoid travel on or immediately below steep slopes where the snow is wet and mushy or where you see fresh rollerball or wet avalanche action.

Problemi valanghivi

  • Loose Wet

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

    With prolonged warming also comes the increased chance of seeing cornice falls, snow shedding from cliffs, and gullies emptying snow, especially during the heat of the day. It might not be spring, but it will be a day to tap into the spring mindset. Big alpine terrain produced some big wet avalanches in the Central Cascades on Thursday. Reduce your exposure as temperatures rise.

    Wet avalanche activity could vary widely across the forecast zone tomorrow. In some areas, they have already peaked, while others have yet to see a significant cycle. Less wind on Friday could increase the chance of seeing more . Many - but not all - lower elevation slopes now lack the snow cover to produce real avalanches. 

    Cloud cover overnight Thursday could affect the level of avalanche activity on Friday. If it’s clear and cooler, expect a crust in the morning and avalanches mostly limited to slopes seeing the sun. If it is cloudier and warmer overnight, you are more likely to see them on all aspects. 

    (12/5/2024)

    Steep rocky terrain is where you are more likely to see loose wet avalanches initiate.

    Photo: Dallas Glass

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1–1.5

    Strong winds hammered upper-elevation terrain on Thursday. Dense or crusty snow at the surface probably reduced the amount of snow available for transport, but there are some slabs somewhere out there. Most should be small but can still do harm if you take a ride on one in consequential terrain.

    Use visual clues like scoured snow surfaces and cornices to figure out where stiff slabs may have formed. Hand shears and test slopes can help you gauge wind slab reactivity. Recently formed slabs sometimes increase in reactivity when they see some warming.

    Small wind loaded features at ridgeline can serve as test slopes to gauge the reactivity of fresh wind slabs.

Avalanche Discussion

New snow from Tuesday’s storm bonded well initially and has generally stayed that way. Moderate wind transport and fresh but shallow wind slab formation was noted along the high ridgelines of Herman in the Baker BC, but slabs were stubborn or unreactive when tested. No observations were submitted from high alpine terrain. Snow surfaces have mostly been affected by wind, sun, or both.

Fewer loose wet avalanches were reported on Thursday in West North than the day before. However, an NWAC Forecaster in West Central found otherwise, with large wet avalanches observed in alpine and mid-elevation terrain.

Previous weak interfaces buried in late January and mid-February have seen extensive loading - 10” or more of precipitation! - and are now considered old news. Widespread avalanche debris from the rain event and the natural avalanche cycle on February 22nd is still evident. 

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