Lawinenlagebericht

Mt Hood

Northwest Avalanche Center
Auf der Karte ansehen

Lawinengefahr

Wed
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
Open full map
Veraltet — dieser Lagebericht ist 4 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Wind slabs will be more stubborn on Tuesday, but they could be large on sizeable alpine terrain features. Be leery of steep slopes below recently formed cornices, choosing lower-angle, well-supported access points if you venture onto the lee sides of ridges. If new snow covers visual clues, probe for firm punchy layers or cut across inconsequential test slopes.

Lawinenprobleme

  • Wind Slabs

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

     A large (D2-2.5) explosive-triggered avalanche in heavily wind-loaded alpine terrain had a 2-3 ft crown. It serves as a strong reminder of the risk when moving into steep terrain beneath or adjacent to corniced ridgelines. Some of these hard slabs may be difficult for humans to trigger, but you probably don't want to test your luck given the consequences. Near treeline, 6-12" wind slabs rest on much lower-density snow giving them a hollow feel if you punch your pole into them. By Tuesday, the 36-48 hour old slabs will be stubborn, but you can still trigger a potentially large slab on a steep, unsupported slope in wind-loaded terrain. Most slabs sit above the 1/14 rain crust which serves as the bed surface for most avalanche activity up to at least 6600 ft. A lower-density snow layer sits just above the slab at the interface of failure. Northerly and easterly aspects have generally received the most wind loading and therefore are the most suspect. Several inches of new snow Monday night could mask visual clues such as textured snow or lens-shaped pillows. Instead, constantly evaluate the depth of the new snow above the 1/14 rain crust. You're entering wind-loaded terrain when the depth increases above the 7-8" mean. Also, look for evidence of widespread sastrugi as you move into heavily wind-affected terrain. These scoured slopes were stripped of snow while slabs lurk on the other side of the ridgeline. Probe for a density interface or hollow-feeling snow. And use small test slopes to evaluate reactivity. Steer around steep, consequential, or unsupported terrain features greater than 35 degrees near or above treeline.

    (1/16/2023)

    Large explosive triggered wind slab. 7000 ft in A-zone. Mt. Hood Meadows.

    Photo: Mt Hood Meadows Pro Patrol

Avalanche Discussion

MLK day featured unexpectedly sunny weather and many backcountry travelers made it into the alpine terrain. Sastrugi (heavily wind-scoured snow) abounded, but riders reported high-quality turns. Such wind-scoured snow should continue to provide enjoyable turns on Tuesday, an excellent alternative to wind-loaded slopes nearby. You can find photos of the sastrugi in the gallery along with more photos of the large explosive-triggered avalanche in A-zone. Below 5000 ft, temperatures were mild enough to moisten the snow surface. Expect a new breakable crust at these low elevations potentially extending somewhat higher in the terrain on steep south-facing slopes by Tuesday.

8-10"+ of new snow fell on Sunday with strong winds transporting that snow through Sunday night creating touchy slabs on Sunday (see photo gallery). A dusting of snow that buried the 1/14 rain crust on Saturday provides a slightly weaker interface (but not persistent grains) just above the 1/14 rain crust . The rain crust should be supportable in most of the terrain. Below the crust, you'll find dry snow with periodic crusts capping layers we've been talking about in recent weeks. While the 1/4 layer was still present on 1/15 in sporadic wind-sheltered terrain such as on Vista Ridge, the 1/14 crust provides a new ground in most of the terrain.

If you're out on the extended weekend, let us know what you see and submit an observation - any information is useful.

 

Abgedeckte Regionen