Avalanche forecast

Mt Hood

Northwest Avalanche Center
View on map

Avalanche danger

Thu
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
Open full map
Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Wind-drifted snow remains primed for human-triggered avalanches on leeward slopes, particularly above treeline.  If you find more than 6" of snow on top of the most recent crust, you can trigger an avalanche on a steep slope. Once the sun comes out, expect a cycle of small wet avalanches on steep slopes that will be most pronounced near treeline.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–2.5

    You can easily trigger an avalanche large enough to bury or kill you above treeline, while human-triggered avalanches will be smaller and easier to steer around near treeline. Tuesday night's rain/snow line reached around 6000-6500. Below that transition, you'll find the refreezing 3/15 crust with an average of 6-8" of snow above it. Above treeline, Mt. Hood Pro Patrol found over 3 ft of snow sitting above the 3/12 crust on lee slopes. These slopes need time to heal before you venture into steep or unsupported terrain. You'll need to carefully evaluate layering within the upper snowpack, looking for punchy snow layers or reactive interfaces on small test slopes before engaging with more consequential steep or unsupported terrain features above treeline.  Cracking or hollow-sounding snow should warn you to stick to slopes less than 35 degrees. Near treeline, use simple slope tests to determine the reactivity of shallow slabs, particularly near avalanche start zones.

    Example: Cracking snow right before the wind slab releases.

    Photo: Adam Ü

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    We expect the most dangerous wet loose avalanche conditions to occur near treeline in less wind-affected snow. Above treeline, snow has been scoured or compacted by wind transport while below treeline, several days of wet loose avalanche cycles have mostly consolidated the snowpack. Winds and cooling temperatures should mostly refreeze the 3/15 crust, limiting the size of these avalanches to the new snow above the crust. However, with 6-8" of expected dry snow available near treeline, these avalanches could become large on a long, steep slope. Loose avalanches gain mass and momentum on the slopes below either a human trigger or where snow sheds off rocks or trees. As soon as you feel the sun's strength, the snow becoming sticky/wet, or rollerballs start up, reduce your exposure to slopes steeper than 35 degrees. We don't expect the sun's energy to be strong enough to affect higher elevation northerly aspects.

    (3/13/2022)

    A ski cut produced this small loose wet avalanche below treeline Sunday.

    Photo: Ron Martin

Avalanche Discussion

An atmospheric river brought a period of mild temperatures that extended through Monday night. We estimate that the snow line reached around 6500 ft and by Tuesday afternoon around 4" of snow accumulated on top of that crust. At higher elevations where the crust fades away, you might find 3-4 ft of snow above the 3/12 interface on lee slopes with much shallow snow on windward slopes. Poor visibility has limited observations above treeline since the storm series began. Mt. Hood Pro Patrol reported easily triggered wind slabs 4-8" deep, running on the 3/15 crust on Tuesday. Additional snow and wind loading will thicken these slabs Tuesday night with cool temperatures slowing the slab healing process on shaded aspects. Mild temperatures below treeline contributed to the continuation of wet loose avalanche cycle below treeline.

Earlier in the storm cycle, human triggered wind slabs and storm slabs 6-12in deep were reported near and below treeline on Saturday and Sunday. Warming temperatures and rain also caused several small wet loose avalanches, with widespread wet activity below treeline Sunday. All recent avalanche activity has failed at or above the old/new snow interface buried 3/12, and we do not expect avalanches to break deeper in the snowpack on old snow layers moving forward. 

Regions covered