Bollettino valanghe

East Slopes North

Northwest Avalanche Center
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Pericolo valanghe

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

Expect dangerous avalanche conditions on Thursday. Strong winds, recent snowfall, and weak layers in the snowpack are a recipe for large avalanches. You may be able to trigger avalanches that break widely across terrain or come down from overhead. Avoid traveling on or under steep slopes until the snow has a few more days to adjust.

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1.5–2.5

    The most dangerous locations will be steep, leeward slopes near ridgetops at mid and upper elevations and large avalanche paths in the eastern portion of the zone. Avoid traveling on or under slopes steeper than 35 degrees, particularly where you see blowing snow or find recently formed wind slabs. At lower elevations, you may still be able to trigger small avalanches in the recent storm snow. In areas of shallow snow cover, avalanches could carry you through rocks and stumps. 

    Another round of strong westerly wind will drift snow on Thursday. Watch for obvious signs of danger like blowing snow, cracking in the snow, whumphing collapses, and recent avalanches. Avalanches could be surprising and break widely across terrain features. All of the recent snow is stressing underlying weak layers. Give the snowpack a few more days to adjust before traveling on large, consequential slopes.

    (1/7/2024)

    Even with little new snow, a natural wind slab occurred between 1/6-1/7 near Harts Pass.

    Photo: Jason Davis

Avalanche Discussion

Observers report recent storm snow heights of 1.5-2 feet since the 8th. Most reports of recent avalanches are size D1-2, involving the storm snow. In some places, there are indicators that the storm brought various older weak layers to their tipping point. This may be especially true as you move farther east of the Cascade crest. On the 10th, observers reported a number of large, natural avalanches over 2 feet deep near Cutthroat Lake (NE, ~6,800ft) that may have run on a crust from December 30th. Observers on Delancey Ridge reported over 20 rolling collapses at all elevations on a similar crust/weak layer that developed during the prolonged dry periods in December. 

"Weak and variable" sums up the snowpack. While you may find up to 6 feet of snow on the ground at upper elevations near Washington Pass, the snowpack is significantly weaker as you move east of the Cascade crest. There are several decomposing crusts and layers of sugary facets that developed throughout December. In some locations, these layers present as individual prominent bands; in others, they all meld together. Near and west of the Cascade crest, crusts are typically thicker and more stout, and the snowpack has fewer weak layers. On the 7th, NWAC staff went near Cutthroat Lake and found near-surface facets forming on south aspects. Crusts (Dec 30th and Dec 5th) with weak, faceted snow below and above failed on isolation in snowpack tests in the upper snowpack.

Even with the recent snow, coverage remains thin at lower elevations and in the eastern mountains. Watch for hitting rocks and logs or falling in open creeks.  If you're in the mountains, let us know what you see. Submit an observation here!

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