Bollettino valanghe

East Slopes North

Northwest Avalanche Center
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Pericolo valanghe

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

You can trigger avalanches where the wind forms fresh drifts at upper elevations. Steer around thick pillows of snow on slopes steeper than 35 degrees. Continue to put space around very large, unsupported terrain features and complex terrain until we can rule out the slight chance of triggering large avalanches on deeply buried weak layers. 

Problemi valanghivi

  • Wind Slabs

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

    Plumes of blowing snow and shooting cracks are "red flag" warning signs that you could trigger a wind slab avalanche. You can also look for deeper, drifted areas of snow. You can use a pole or probe to feel the stiffer snow and compare the deeper drifts to wind-sheltered areas. Steer around slopes steeper than 35 degrees where you find these snowpack characteristics. Be aware of cornices and make sure not to travel on them or linger under them. 

    Expect another 1-2" of new snow. Winds picked up on Sunday afternoon and could be strong enough to transport new and existing snow. Older slabs that formed on the 1st are now difficult to trigger.

    (1/26/2024)

    Wind-sculpted features at upper elevations in the Blue Lake basin.

    Photo: Will Govus

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    2–2.5

    This is a low-likelihood, high-consequence problem. Use careful terrain selection and snowpack assessment until we can further rule it out. If you managed to trigger an older weak layer, an avalanche could break very deep and widely across terrain features. Continue to put a large terrain buffer between your group and large, unsupported terrain features and start zones.  If you find hard crusts at least 4 inches thick in the upper snowpack, there's a good chance that avalanches will be very difficult to trigger in that area.

    There are two persistent weak layers that could still be a problem: small facets buried on or around January 8th in the top 1/2 of the snowpack and a series of crusts and large weak grains from December in the lower 1/3rd of the snowpack.  You can use snowpack tests to identify and assess these weak layers. 

    (1/30/2024)

    Multiple crowns of natural avalanches, including some that may have run on deeper weak layers above the Hairpin Valley at Washington Pass. These likely ran between Jan 27-29th.

Avalanche Discussion

Conditions are variable. At low elevations up to 6,000, the snowpack is very rain-affected. Above that elevation is a mix of rain effects and, more recently, drier snow. Up 8" of dry snow is on the surface and you can expect a couple more inches by Monday. Observers have reported rain runnels and glide cracks up to 7,000ft. There's also enough dry snow for decent travel conditions and wind slab hazards at upper elevations. Check the upper snowpack to see how hard and how frozen, moist, or dry the snow is. You can also check the old, weak layers (early January facets in the upper 1/3rd and Dec facet/crust in the lower half) to see if they've been transformed by meltwater. 

From January 27 to February 1st roughly 1.75" of water equivalent fell, much of it was rain at low elevations. Observers have reported variable impacts of this storm based on elevation and location in the range. A widespread cycle of wet avalanches occurred. Some were very large, to size D3.  While poor visibility and wet stormy weather prevented gathering details of many of these avalanches, at least some appear to have run on old, weak layers. An incomplete tally of the avalanches that we know about includes:

  • Natural wet loose and wet slabs on east to southeast aspects of Cutthroat Peak and Whistler Mtn
  • Multiple natural wet avalanches on west to southwest aspects of Kangaroo Ridge up to size D3
  • Natural wet avalanches in the west fork of Cedar Creek up to size D3.
  • Numerous natural wet avalanches at lower elevations on banks and typical paths that hit Highway 20, including the "Cutthroat paths," just south of Cutthroat Lake Rd. Some ran to the ground.
  • Natural wet slab avalanches, likely running on deeper weak layers on unsupported slopes, on north aspects, 7,400-6,800ft in the Hairpin Valley.
  • A very large persistent slab avalanche was remotely triggered on a west aspect, 6,000ft, Leap Creek (D3, Jan 27th).

 If you're in the mountains, please let us know what you find.

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