Lawinenlagebericht

Mt Hood

Northwest Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
1 · Gering
Waldgrenze
1 · Gering
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 6 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

At upper elevations you can trigger an isolated wind slab on steep terrain rollovers. Near and below treeline, warming temperatures and sunshine could produce loose wet avalanches during the middle of the day. Complex temperature and wind patterns created differences in the upper snowpack across the zone, so if something differes from the forecast, dial back your ambitions.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    1–2

    You are most likely to trigger an isolated reactive wind slab on steep, unsupported terrain features near and above treeline. A wind slab could be large. Very strong winds built shallow but reactive wind slabs Monday. Reports from Tuesday suggest that winds were strong enough to redistribute the snow into a patchwork of small wind slabs rather than thicken existing wind slabs. Wednesday, the east wind continued to keep the snow surface cool and wind transport active despite above freezing air temperatures, so shallow recently formed wind slabs may exist at upper elevations. We expect you will be most likely to trigger snow from the easterly wind transport following the storm.

    Blowing snow, firm and textured snow, and cornice formation are all evidence that wind slabs are likely to be forming on lee slopes.

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    1

    Much of the snow on Mt. Hood has been affected by warmth (although there have been cold periods) and sunshine.  After a cloudier day on Thursday that limited loose wet avalanche activity in spite of the warm temperatures. Rollerball activity did not gauge deeply due to the density of the snow. Pay attention for wind-sheltered areas where the sun may initiate rollerballs, a sign that you could trigger a loose wet avalanche.  As snow surfaces warm under direct sun adjust your aspect to avoid triggering a loose wet avalanche.

Avalanche Discussion

The Mt. Hood zone has transitioned from cool E flow on Wednesday to mild W flow on Thursday with warm temperatures and sunshine under a rebounding high pressure on Friday.

Last weekend's beautiful weather left snow surfaces at most elevations and aspects firm either by wind scouring or the sun's melt/freezing action. Monday's powerful winds and heavy snow deposited an erratic arrangement of snow depths and textures. Areas in the alpine are scoured bare or packed with dense wind affected snow. At lower elevations, sun-exposed slopes have begun to feel the effect of rising temperatures while shaded slopes still hold cold, poorly bonded snow.

It's important to remember that while the snowpack is generally stabilizing, vastly different conditions will be found at different elevations and on different sides of the mountain.  At lower elevations, recognize where sun-affected snow is beginning to form roller balls and pinwheels suggesting you could trigger loose wet avalanches on slopes steeper than 35 degrees.  Recognize when you transition into wind affected terrain and navigate around cornices and steep pillow-like drifts.

As we head into a week of high pressure remember that NWAC does not have enough consistent and reliable information to accurately forecast for the uppermost slopes of Mt Hood. If you choose to travel in the highest alpine terrain, carry avalanche rescue equipment and be prepared to make your own assessments.

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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