Bollettino valanghe

East Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

Wet avalanche concerns will ramp up as the day progresses. Pay close attention to your aspect, timing, and signs of warming on steep terrain. Move to shadier slopes or lower-angle terrain if the upper snowpack feels wet, sloppy, and unsupportable. 

Problemi valanghivi

  • Loose Wet

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

    Your chances of triggering wet avalanches will increase as the day warms up. At the start of the day, a thin surface crust may limit wet snow instabilities, but look for this crust to break down quickly as the morning progresses. By the afternoon hours, steep sun-exposed slopes will feel wet and unsupportable - increasing your chances of triggering wet avalanches on steep, unsupported terrain. 

    The threat of wet loose avalanches generally follows the sun around the compass: SE-E aspects in the morning, S-SW facing slopes mid-day, and SW-W in the afternoon. You can track your boot and sled penetration and look for obvious signs of warming like rollerballs as you move from aspect to aspect. If you’re sinking past your boot-tops in wet snow, consider moving to shadier aspects or lower-angle terrain.  Any triggered wet loose avalanche could have a less-than-ideal outcome if terrain traps are present. 

    As warming temperatures persist, larger wet slab activity becomes increasingly more possible. We had enough recent avalanche activity during our last cycle that larger wet slabs releasing as the temperature climbs isn’t fully out of the question. While this seems unlikely given our snowpack structure, wet snow can be tricky to forecast.  Monitor overnight refreezes and water moving through the snowpack.

    (4/13/2023)

    Rollerballs and small wet avalanches like this are indicators that wet loose avalanches could be possible in similar steep terrain. 

    Photo: Matt Primomo

Avalanche Discussion

Break out the sun hoodies and Hawaiian shirts; the January heat is ramping up. Freezing levels will be absurdly high, pushing up to 12,000 ft by Wednesday afternoon. The snowpack is starting to resemble something you’d see in April rather than January. 

Based on telemetry, we suspect light rain fell up to most ridgetops in the zone. This likely led to some wet loose avalanche activity and decimated the good riding conditions we enjoyed this past week. Be prepared for wet surfaces, crusts, and challenging travel. If you’re far enough east or south, you could find dry snow on northern aspects. If that's the case, keep isolated instabilities within wind-drifted snow on your radar specicially in complex, upper elevation terrain. 

Prior to the warm-up, this past week brought 1-2 inches of snow water equvialnet to the East South mountains. This equated to 1-2 ft of recent snow over a crust that was buried on January 3rd. During this period, most avalanche activity was confined to heavily wind loaded terrain. Below the surface instabilities, backcountry travelers generally found a strong, well-bonded snowpack to the January 3rd crust. While isolated, but still noteworthy, a layer of buried surface hoar was found around Ahtanum Meadows (observation here) and was likely the culprit of a nearby avalanche on Dome Peak near the South Fork of the Tieton (observation here). We suspect these instabilities are largely a thing of the past and will be replaced with wet avalanche concerns as warm temperatures persist. 

Despite the new snow, the snowpack remains thin. In choosing terrain, consider the consequences of a slide. Look for slopes with a clean runout free of bone-breaking trees, creeks, and rocks.

Regioni coperte