Bollettino valanghe

East Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

You can trigger avalanches where the wind builds fresh slabs at upper elevations. Steer around pillows of snow and drifts on steep roll-overs. If you're in the eastern mountains, consider that triggering large avalanches on older buried weak layers may still be possible at mid to upper elevations.

Problemi valanghivi

  • Wind Slabs

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

    Steer around smooth pillow-like drifts on steep leeward slopes.  You can also choose lower-angled portions of a slope or entrances off of ridgelines to avoid triggering a wind slab avalanche. Blowing snow can point to which aspects are being loaded.  If you see red flag signs like shooting cracks or new avalanches, choose lower-angled or wind-sheltered terrain. The wind was strong enough to transport snow over the past 2 days. More north wind could build slabs at upper elevations on through Tuesday morning. 

    (1/5/2023)

    Cracks shoot through wind-drifted slabs just below a ridge. 

    Photo: Frank Clements

Avalanche Discussion

On Monday and Sunday, observers triggered small avalanches in pockets of freshly drifted snow. These occurred on a mid-slope roll on the Lyall glacier and at 6,900ft, SE aspect near Snagtooth Ridge, respectively. On Monday, observer Willie Webster found large (5-10mm) rounding buried surface hoar (Jan 5) near the crown of one of many avalanches that ran during the MLK storm near Rainy Pass.

The January 5th buried surface hoar is the main persistent weak layer that we've been tracking in the zone. Near Washington Pass, it's  ~2' below the snow surface and is unreactive.  It hasn't been involved in any human-triggered avalanches since 1/12. Willie's observation near Tiffany Mt on the 19th indicated that triggering avalanches on the 1/5 surface hoar may still be possible in this portion of the zone. Persistent slab avalanches are unlikely in the foothills and low-elevation mountains of the Methow Valley, where rain surrounding MLK weekend transformed weak layers to melt forms. On Wednesday, Willie investigated a very large slide in Liberty Bowl/Blue Lake Pk that likely occurred on January 13 or 14th. The avalanche failed on the Christmas crust and stepped down to the mid-November facets (11/22).  A crown depth of 5-8 feet was measured.  While this avalanche was an anomaly, a look through the depths of our database shows other natural avalanche cycles on these layers.

The last significant cycle of avalanches occurred around the 13th and 14th with wet avalanches in the lowland hills gouging to the ground and multiple very large natural avalanches running on persistent weak layers higher in the mountains. Check out the media reel below and our observation platform to see more.

Regioni coperte