Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
Open full map
Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

A shift in weather from cold and stormy to warm and dry is in store for the PNW. So increasing temperatures and sun will make wet avalanches the primary concern on Saturday. Travel cautiously in steep terrain, and if you find snow that feels wet and heavy, it may be time to move to shady or low-angle slopes.

Problemi valanghivi

  • Loose Wet

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

    Freezing levels begin an uphill march overnight on Friday and are forecasted to reach 7500ft by Saturday evening. Many weather stations have shown above freezing temperatures at some point over the last two days, and slopes up to 4500ft have developed thin crusts on the surface. However, further increasing temperatures and sunny skies might be the tipping point for wet avalanches on all aspects on Saturday. Thick crusts under the storm snow from 1/30 - 2/1 can act as a good bed surface for wet avalanches to run on. In areas near the crest and further north in the zone, there may be a few inches of new snow overnight on Friday. Dry snow is particularly susceptible to warming, and danger may increase quickly, especially on slopes in direct sun. If you see pinwheels or rollerballs and the snow feels wet and heavy, it might be a good time to head toward lower angle slopes. You can also observe how wet snow reacts when you push on small test slopes. If the wet snow gathers momentum and entrains additional snow, wet loose avalanches are possible. Be cautious of traveling above rocks, cliffs, creeks, or other obstacles that can increase the consequences of getting caught.

    (12/21/2021)

    Pinwheels like this are an indication that wet loose avalanches may be possible. 

    Photo: Matt Primomo

  • Wind Slabs

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

    A storm bringing snow and strong winds will impact the region from Friday night into Saturday. There is some uncertainty with how much precipitation will make it over to the east slopes of the Cascades, but there is a chance that areas in the East Central Zone near the crest will pick up 4-8inches of snow overnight. Strong winds with this storm may build small wind slabs on lee aspects. Look for signs of wind drifted snow that feels hollow or looks pillow-like. You can also use visual clues such as cornice direction or drifts around rocks and trees to indicate wind direction. If you feel the snowpack collapse or observe shooting cracks in wind-exposed terrain, you should steer around recent drifts and slabs on slopes steeper than 35 degrees. 

    (2/1/2022)

    Shooting crack on a wind-loaded feature at 5,800ft in the upper Salmon la Sac drainage.

    Photo: Ryan Minton

Avalanche Discussion

On sheltered areas on north and east aspects, facets over a crust have been observed at mid-elevations beneath the storm snow from 1/30 - 2/1. This layer seemed inconsistent in distribution and may not exist in wind-exposed terrain. Avalanches triggered on these weak layers tend to break farther or wider than anticipated. Use extra caution in sheltered terrain near the crest on NW-NE aspects. There is uncertainty about the distribution and extent of this layer, but it is only 1-2ft deep, so you can dig down to identify these layers quickly as you move through the terrain. If you find weak, sugary snow over firm melt-freeze crust under a cohesive slab, you could trigger surprising avalanches on steep slopes. In areas where this layer was observed in the East Central Zone, the facets were generally small and unreactive. However, reports of collapsing on a similar layer in the Stevens Pass zone are notable, and it is important to track this interface as you enter new terrain. NWAC observer Drew found this crust/facet combo out at Holden, but there isn't enough snow on it to be problematic yet. We will continue to monitor this layer as we get additional snow. Where there is no faceted snow at the interface, observations throughout the zone have found the storm snow to be well-bonded to the crust layers. New snow amounts are minimal in the eastern portion of the zone, and any avalanche hazard is likely isolated to shallow wind slabs at the highest elevations near ridgelines. 

Regioni coperte