Avalanche forecast

Mt Hood

Feb 10 – 11, 2019Northwest Avalanche Center
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Archived · expired 8 years ago

Avalanche danger

Tue
Alpine
4 · High
Treeline
4 · High
Below
4 · High
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Highlights

Very dangerous avalanche conditions are developing at Mt. Hood as heavy snowfall combined with strong to extreme winds produce very large and reactive slab avalanches. The slab is developing above weak old snow sitting on a strong crust. Avoid all terrain where avalanches start, stop, or run!

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–2

    Strong to extreme winds will blow several 1-2 feet of new, low-density snow far and wide. Any wind-affected snow is likely to be reactive. Wind slabs may be very large and may form at any elevation, may cross-load slopes into the treeline band, and may run full path. The wind slabs will be sitting on faceted (weak) snow above a firm crust (sliding bed surface), which is a prime recipe for very dangerous slab avalanches. Stick to lower angle terrain in dense old-growth trees where safer conditions may be found.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1

    Heavy snowfall will form a deep slab that will produce large natural and human-triggered avalanches. This slab may be reactive within the storm snow or on the new/old snow interface. The last storm snow buried surface hoar or near surface facets near and below treeline or a crust BTL and on sun-affected aspects. Areas that had weak underlying snow are most likely to produce large avalanches. Winds will keep the storm slab problem confined to lower-elevation sheltered terrain. Don’t be lulled into thinking that open slopes are safe at any elevation.

Discussion

Snow and Avalanche Discussion

A one-two punch of storm systems will impact the Mt. Hood area through the end of the day on Monday, bringing high snow loading rates and tremendous wind transport to form deep slabs and wind drifts. Very dangerous avalanche conditions will develop from late Sunday night and increasing throughout the day on Monday. Safe travel may be found only in non-avalanche terrain and in lower-angle old growth trees.

Professions triggered 1-2’ wind slabs with slope cuts on west through southwest slopes in the White River Canyon at 5500 to 6500 ft on Sunday afternoon.

Snowpack Discussion

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