Lawinenlagebericht

East Slopes Central

Northwest Avalanche Center
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Lawinengefahr

Mon
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
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Kernpunkte

Warming temperatures may contribute to dangerous conditions with the massive amount of new snow on Sunday. Deep and unsurvivable slab avalanches could be triggered from recently wind loaded areas. These, along with the potential for very large loose wet avalanches should shape your travel to avoid steep slopes and stay well away from runout zones. Continue to stay well away from roof avalanche impact zones.

Lawinenprobleme

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    2–3

    The deep new snow is not fully settled yet,  so warm temperatures and sun may initiate a round of destructive loose wet avalanches. Avalanches could occur in atypical places because now they have enough snow. Steep roadcuts near town, and any very steep terrain that catches the sun could be dangerous. The 4ft of storm snow could also glide off rock features at lower elevations. 

    Stay out from underneath very steep slopes that catch the sun, especially mid-day. If you notice glopping and heavy, wet snow over dry snow surfaces, it's time to get off steep slopes.

    Roof avalanches will continue to pose a threat, so use caution and make sure children and pets stay well out from impact zones.

    (1/8/2022)

    Multiple avalanches, with recent loose wet slides off steep rocky features in the lower Icicle.

    Photo: Matt Primomo

  • Deep Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–3

    The potential exists to trigger unsurvivable avalanches on Sunday. Heavy storm totals along with intense wind drifting has created thick, and dense slabs over a decomposed crust from the Solstice and other deeply buried weak layers. This layer is anywhere from 3ft to 8ft deep. Dangerous conditions exist because these slabs may only need a trigger. Rapid warming may increase the sensitivity of these monsters on Sunday. Very large, deep slab avalanches could be initiated from the edges of steep slopes or from below. Cornices could collapse if you go near them and trigger very large deep avalanches. 

    Keep your slope angles below 30 degrees. Stay well out from underneath any large features with recent wind loading. Recognize that avalanches could be triggered even after a person or two, or three have been on the slope. This problem appears most prominent in the eastern half of the zone, although likely exists elsewhere.

    In the open foothills, avalanches have been breaking on the ground. Stay off of steep slopes if they have not avalanched yet, as they may only be awaiting a trigger. Whumphing collapses are a sign of persistent instability.

    (1/8/2022)

    Deep slab release at Mission Ridge with control work. This slide had a crown from 3'- 5' deep, and the hangfire was triggered remotely.

    Photo: Drew Carlton

Avalanche Discussion

It was a storm for the ages for much of the East Central zone, and many areas including towns picked up a whopping 3-4ft of new snow in a two day period. A storm total of 50" with 2.9" of SWE was recorded in Leavenworth. The higher elevations surely have even more snow, but many of our weather stations are down and access to the higher mountains has been impossible. We have uncertainty with how the warming temperatures aloft will affect stability on Sunday, but we do know that many large and very large avalanches have occurred as recently as Saturday. Control at Mission Ridge pulled out a 3'-5' deep hard slab on the Solstice Crust, and 5' deep hangfire was easily triggered as well. Backcounry travelers reported touchy conditions, and isolate whumphing near Mission Ridge on Saturday. Folks reported whumphing collapses, shooting cracks, and a widespread avalanche cycle in the low elevation hills of the Columbia Basin on the 7th. I could make out large debris piles in many of the drainages in the lower Tumwater and Icicle Creek, and spotted two fresh D3's on Saturday. These slides carried trees with them and one came within a few hundred feet of some houses. 

There have been at least two roof avalanche burials in the past few days. An 80 year old was buried for 9 minutes in Rosly on Friday, but luckily recovered alive with help of a quick response. Another roof avalanche occurred on Thursday in the Plain/Lake Wenatchee area, and luckily the person was dug out alive. Many roofs have been shedding and there have likely been many other close calls. On Thursday morning, an avalanche damaged a house south of Entiat. The residents were evacuated safely, and we hope to visit the site on Sunday. Tumwater Canyon remains closed, and WSDOT reported over 208 debris piles on Highway 2 up to 15 feet deep, and several ran into the river. 10 of those slides were very large. 8 very large slides over the road were reported in Icicle Creek. Roads have been hit by avalanches in many other areas including; Hwy 97A, Mission Creek, Olalla Canyon, and Entiat River rd. 

Observers documented many different weak layers in the zone prior to the storm. The recent layers were large stellars, facets and surface hoar from 1/2 and 12/29. A decomposing crust from the Solstice was the bedsurface for some slides at Mission Ridge. An even deeper crust from Early December was observed to have propagation potential in the Icicle on high elevation slopes. At this point, these layers could be from 3-8ft deep, and act as the weak layer for slab avalanches.

Many great Observations have come in from the area. Thanks, and keep them coming as we unravel the saga of this epic storm.

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