Lawinenlagebericht

Mt Hood

Northwest Avalanche Center
Auf der Karte ansehen

Lawinengefahr

Thu
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
Open full map
Veraltet — dieser Lagebericht ist 5 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Large, old wind slabs linger above treeline and you can still trigger them on steep rollovers. Wet avalanches are more likely further down the hill where you find dry snow near the surface. If the sunshine and warm temperatures create sticky snow, adjust your aspect and choose slopes less than 35 degrees.

Lawinenprobleme

  • Wind Slabs

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

    Recent natural wind slabs were confirmed above our NWAC forecast terrain, but we think that similar conditions exist into the NWAC above treeline band. A period of extreme winds and significant new snow Thursday through Saturday morning built large wind slabs. Additional wind transport likely added to the slabs on Sunday. We're at the tail end of the life expectancy for these wind slabs, but you can still trigger them on wind-loaded convex rollovers. If triggered, slabs are likely to be firm and several feet deep.  Look for recent cornices, stiff and textured snow surfaces that may crack under your feet as you travel. Where you see these things, navigate around slopes steeper than 35 degrees, particularly where the slope rolls over.

    (3/1/2021) Large explosive-triggered wind slab on a steep slope above treeline.

  • Loose Wet

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

    A third warm day will see the snow surface transition and create the potential for wet loose avalanches as the sun moves around the dial. The day should start with a firm, supportable crust on some aspects, breakable crusts on others, and dry or chalky snow northerly aspects. We expect wet loose activity to continue to decrease after several days of mild temperatures, but we can't rule out a larger avalanche entraining more deeply. Pay attention for areas where the sun warms previously dry snow. Pay attention to pinwheels, rollerballs, and wet or sticky snow 6" deep such as those observed here. If you encounter any of these conditions, seek slopes away from the sun and less than 35 degrees. Use extra caution above terrain traps like cliffs and creeks.

    Example: Rollerballs entraining sticky snow near the surface. Photo: Ashley Turcott.

Avalanche Discussion

A number of natural and human-triggered avalanches and a large explosive-triggered avalanche occurred on Monday. These avalanches remind us that we're 5 days out from a major storm and avalanche cycle featuring 50 inches of snow since 2/22 along with extreme winds. That snow sits above a freezing rain crust up to roughly 7000'. A snow profile adjacent to the Hinterlands Avalanche at Mt. Hood Meadows shows a 40" slab above weak snow grains sitting on the freezing rain crust. These weak grains are healing and avalanches are unlikely to be triggered at this interface moving forward.

Mt. Hood pivoted rapidly away from a cold, stormy pattern right into spring-like weather. Daytime freezing levels exceeded 6500 ft Sunday, Monday, and Tuesday. Public observations noted significant rollerball activity on Sunday and likely wet loose avalanches. If you see large or recent wet avalanches, the snowpack may not be handling this transition as well as we expect and you should give yourself an extra margin of safety.

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.

Abgedeckte Regionen