Avalanche forecast

Mt Hood

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

Wind slabs will be 3-4 days old on Tuesday and they are stubborn to trigger, but can still be large. Your danger will be greatest at upper elevations on steep or extreme terrain features and terrain rollovers. Look for clues such as cracking snow, whumphs, or tell-tale signs of wind-loading to identify potentially unstable slopes nearby.

Avalanche problems

  • Wind Slabs

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

    Reactive wind slabs may linger in specific terrain features at upper elevations, such as on colder northerly aspects and heavily wind-loaded slopes. They are most likely to be triggered on a steep, unsupported slope approaching 40 degrees. Near treeline, the slabs are isolated. Wind slabs continue to stabilize quickly with help from the milder temperatures at upper elevations, where temperatures rose above freezing on Monday.  As the danger trends downward pay attention for clues that you might be venturing into unstable terrain. Firm and textured snow, cornices, and collapsing or "whumphing" sounds in the snow are evidence that you could trigger a wind slab on similar aspects. 

    Avalanches over the weekend remind us that wind slabs can take up to five days to fully heal. Strong winds Friday - Saturday redistributed 11-12" of snow that fell Friday into Saturday morning and that has settled into 5-15" on the crust at 6000 ft as of Monday. This produced Wind Slabs up to size 2.5 (large-very large), with crowns 1-3 ft deep that Mt. Hood Meadows Pro Patrol triggered via large explosives over the weekend. Some broke within the storm snow while others stepped down to the new/old snow interface. Several very large avalanches released naturally prior to the most recent storm. These ran on weak snow above 12/9 rain crust. While we don't expect the older layers to be reactive on Tuesday, they are worth watching as we head into the next storm cycle.

     

     

    (12/27/2020) Slab structure in a small cross-loaded wind pocket. NW 6400 Norse Peak. 15-20cm deep.

Avalanche Discussion

Avalanche danger will rise sharply Tuesday night into Wednesday as the next major storm arrives. 

Wind Slabs remain the primary problem on Tuesday. In spite of the warm temperatures at upper elevations on Monday, a heavily wind-affected snowpack was not prone to Wet Loose activity. With cloud cover arriving on Tuesday, Wet Loose is not likely to materialize. Storm slabs that were reactive Sunday were no longer reactive in wind-sheltered terrain by Monday.

The weather is not expected to change the avalanche hazard on Tuesday. Winds should increase into the moderate range on Tuesday, but MHM Pro Patrol found limited snow available for transport above treeline, where they found widespread wind-affected snow with 1/2 inch of ski penetration.

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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