Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

Plenty of new snow is out there, particularly in areas near the Cascade Crest. The most likely places to trigger a large avalanche will be at upper elevations in wind drifted snow. So avoid steep slopes below ridges, the base of cliffs, and steep convex rolls where you find deep, textured drifts of snow.

Problemi valanghivi

  • Wind Slabs

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

    You can still expect to find reactive wind slabs on steep wind-loaded slopes and terrain features. The most likely places to trigger wind slabs will be steep slopes below ridges, steep convex rolls, and the base of cliffs. You will likely need to steer around these wind slabs in steep open terrain at lower elevations, but avoiding these wind slabs in alpine terrain may still be challenging. Feel for stiff over soft snow layering and use inconsequential test slopes to identify and avoid areas of unstable wind-drifted snow. Areas sheltered from the wind or low-angle slopes will be the best option to reduce to likelihood of triggering an avalanche. There has been significant snow and winds over the last 24hrs, and we are not entirely out of the stormy period yet. There is some uncertainty with an upslope easterly storm beginning to impact the East Central later on Saturday. So while older wind slabs may be trending towards stubborn, new wind slabs may form quickly and be easier to trigger. Winds are forecasted to shift easterly, and fresh, shallow wind slabs may form on previously wind-scoured slopes. Pay close attention to wind direction and blowing snow to identify locations where snow is actively drifting into shallow slabs. 

    (2/28/2023)

    A small wind-loaded test slope produced this mini wind slab. 

    Photo: Katie Warren

  • Loose Dry

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

    Some areas of the East Central close to the crest may have picked up over 1.5ft of snow over the last 48hrs, and you could trigger fast-moving dry loose avalanches in very steep terrain. These avalanches often start directly below your feet or as snow falls from trees and cliffs onto the slopes below. While they may tend to be more predictable than slab avalanches, avoid being caught off guard in very steep consequential terrain where you could be carried over cliffs or buried deeply in gullies. 

    (2/22/2023)

    An example of very small dry loose avalanches. 

    Photo: Katie Warren

Avalanche Discussion

During the day on Thursday, a convergence zone parked just north of Snoqualmie Pass, producing heavy snow totals in the Salmon La Sac and Upper Icicle areas. This convergence zone drifted north overnight, favoring the HWY2 corridor near Stevens Pass, with snow totals around 15 inches. These areas near the crest have significantly more snow than areas further east,  so anticipate the potential for larger avalanches if traveling in these regions. 

Recent observations are that the new snow has little slab structure in most sheltered locations. However, with this much recent snow, there may be areas where you could still trigger a storm slab. Southern aspects may be suspect due to a slick crust that formed just before this storm. An observer in the Icicle Creek Drainage triggered a small slab on a steep convex roll that ran on this recent sun crust. While this problem is likely isolated in distribution, as we step out from a storm cycle, monitor the reactivity of the new/old snow interface as you travel and enter new terrain slowly. Low-elevation areas further east in the zone did not receive much snow, and it is probably unlikely to trigger an avalanche in these areas. There is some uncertainty with the timing and moisture amounts with an upslope easterly storm that will impact the East Central Zone later on Saturday. But be prepared for the possibility of high precipitation rates and snow piling up in the late afternoon. You can find 1-3ft of recent snow sitting over a crust from Valentine's Day, which often presents as a crust/facet sandwich, with weaker snow beneath the upper crust. Observations indicate quite a wide variability in the structure of this layer. There has been a couple of isolated observations of instability on this layer in the Icicle drainage. We have yet to observe avalanche activity on this layer but continue to monitor it as snow adds up. If you get out into the mountains, submit an observation to share what you found.

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