Avalanche forecast

Mt Hood

Northwest Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

Slabs will be easy to trigger and dangerous on steep, exposed lee slopes. Warning signs including active wind loading, firm but hollow feeling snow, or propagating cracks all point you to safer travel along ridges, windward slopes, or in well-forested terrain.

Avalanche problems

  • Wind Slabs

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

    The extreme winds that Mt. Hood experienced on Thursday are typically too strong to productively form slabs on open slopes. However, as these winds ease into moderate-strong range, we're entering the productive range for slab formation near and above treeline. We're expect another 6-8" of snow to provide plenty of ammunition for the winds. Slabs will be widespread, large and reactive to human trigger near and above treeline. Note signs of wind loading including active transport, sharp cornices, rounded pillows. Upside-down layering that makes for challenging uphill travel or firm and punchy layering are both warning signs. Slabs will continue to build over the 3/1 interface. This will be a new/old snow interface in most areas, but may include a melt-freeze crust on steep SW-S-SE aspects or isolated patches of surface hoar that may have been preserved on sheltered open slopes.  Crusts and particularly any buried surface hoar could produce wider propagation.  Avoid wind-loaded slopes 35 degrees and steeper at all elevations, giving yourself a wider margin of safety if you see shooting cracks or whumphs: your final warning signs not to step out onto a steep slope.

    (1/4/2023)

    Winds forming reactive drifts near Timberline earlier in the season.  Shooting cracks are a red flag to stay off of steep slopes at any elevation.

    Photo: Joe Dellaporta

Avalanche Discussion

Extreme winds and poor visibility limited observations on Thursday to below-treeline terrain. After a few days of great riding conditions on shadier and more wind-sheltered spots, 3-4" of snow was redistributed and formed reactive slabs below treeline on Tom, Dick, and Harry running easily on the new/old snow 3/1 interface (see photo gallery). Conditions have changed drastically below treeline since Wednesday and your mindset should adjust accordingly. You may still find high-quality snow as colder, drier snow well below the treeline, but constantly monitor for wind-affected layers as you ascend.

On Wednesday,  surface conditions were quite variable with NW winds drifting snow in the alpine,  rollerballs observed on steep sunny slopes, and dry snow and good snow conditions on cooler slopes at lower elevations.  Forecaster Joe Dellaporta found widespread surface hoar sparkling on the snow surface in these sheltered areas.  We're not yet sure whether this survived in any open slopes well below treeline, but we'll be searching for it and we hope you'll let us know if you find it!

Prior to the incoming storm, the Mt Hood Meadows weather station had recorded a storm total of 27 inches (2.23 inches SWE) since Feb 26th. On Tuesday morning the Mt Hood Meadows Pro Patrol triggered a few large avalanches (D2) with explosives. One of their bigger results on an ESE aspect at 6200 ft,  broke 18-24” deep and failed just above the new/old snow interface. 

As the snow keeps piling up, keep your partners in close sight and give tree-wells a wider buffer than normal.

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