Lawinenlagebericht

Olympics

Northwest Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

Rainfall creates the conditions for shallow natural or human-triggered avalanches. These avalanches will be large enough to harm you where this layer of slushy snow is 4" or deeper, such as on the lee sides of ridgelines, upper elevations, and down into middle elevations of the southern and eastern Olympics. Push some snow down a test slope to assess risk on larger steep slopes nearby.

Lawinenprobleme

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    It will be fairly easy to get the surface snow moving on Friday. The question is whether there is enough recent dry snow for avalanche activity substantial enough to harm you. In short, the degree of hazard in your terrain depends on the amount of snow received Wednesday night. The hazard in this zone is driven by portions of the southern and eastern Olympics that receive 6" or more of snow above 4500-5000 ft while hazard may be low along the northern edge of the Olympics. On Friday, rain-saturated snow may shed off rocks and cliffs, entraining on the slopes below. Riders can also trigger small wet avalanches on a slope. The initial dry to wet snow transition likely takes place Thursday night, so the typical volley of rollerballs may have passed. Your best tool to assess the hazard will be frequent small-slope tests as you ascend into areas with saturated snow you sink into past your ankles. In areas where wet snow is shallower, this layer may not exist or pose real hazard, such as on windward slopes or at lower elevations. Pay particular attention to areas where snow could pile up more deeply in a terrain trap and harm you. Avalanche danger is likely to increase during and after periods of moderate rainfall. Steer around steep slopes where wet snow still needs time to consolidate. Remember that wet snow has a lot more mass than dry snow, so even a small avalanche will gain steam and become powerful.

    Example: Small wet loose natural avalanche activity in a terrain trap.

    Photo: ONP rangers

Avalanche Discussion

Hurricane Ridge picked up 2-3" of higher density snow above the 4800 ft snow line Wednesday night. This snow was moistened by above-freezing temperatures on Thursday. This created conditions for snow that could be easily pushed into shallow avalanches. While this snow wasn't quite deep enough to produce avalanches that would harm you on most slopes, they might on a very long steep slope where an avalanche could gain momentum, or where a terrain trap such as a rock or cliff is involved. The recent snow sits above and is well bonded to the Late January Interfaces (crusts in the Hurricane Ridge area), formed by over 2 weeks of dry weather. On Thursday, ONP rangers found these crusts to be supportable on the southern half of the compass, but variably supportable where they were decomposing from below on the shaded aspects. Late last week, shaded aspects had 2.5" crusts with decomposing 0.5 mm facets below them. The crusts are sufficiently thick that they are likely to form a new ground for avalanche activity in most of the Olympics.

We're expecting 0.4" of water equivalent at Hurricane Ridge over the next 24 hours, plenty to saturate the shallow recent snow. Rain is likely to saturate snow into upper elevation terrain, but expect some fluctation in snow levels and potentially some wet snow accumulating at the highest elevations. Recent snowfall has improved riding conditions.

The Buckinghorse Snotel at 4500 ft in the Southern Olympics saw an 8" increase in snow depth Wednesday night. If you travel to portions of the southern or eastern Olympics, avalanches will be larger and easier to trigger. If you find more than 6" of wet, sloppy snow above the Late January Interfaces, avalanches could be larger and more dangerous than forecast. Remember that the size of an avalanche scales with the length of a slope steeper than 35 degrees. If you intend to travel in these areas, you may find similar conditions and amounts of snow to the West North. Consider reading their zone forecast for a more detailed view of what you might expect. We don't have any direct information on the ground, but we do expect 2-5 times as much precipitation (0.75 - 1.5") of precipitation in these areas, so the recent surfaces snow will be come very saturated. 

We're not sure whether rainfall will re-ignite old glide activity. Keep giving brown frowns respect on the slopes below and see some photos in the gallery:

  • A large 1.5-2 meter deep open glide crack was reported on 01/18 on a NE aspect at 5600 ft off the road to obstruction point.
  • A glide crack was observed, in North Bowl just below Sunrise Point on 01/17. The timing of the crack opening remains uncertain.
  • A large glide avalanche was reported on 01/15 on a steep N-NW aspect on the trail to Hurricane Hill (Steep and Icy Path). The exact timing of the avalanche is unknown.

Low snow hazards haven't gone away. If anything, the recent snow may cover up shallow hazards. Conditions are thin in the woods. Lower elevations barely have enough snow to ride in portions of the Olympics; and the low tide also limits avalanche activity at these elevations.

Weather station note: We are working with the NPS to restore communications to the Hurricane Ridge weather station.  Right now, we don't have an estimated return time. 

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