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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Highlights

Deep low-density snow will warm abruptly on sun-exposed slopes. Expect plenty of shedding off rocks, cliffs, and trees with entrainment producing avalanches that could bury you. As you move into middle and particularly upper elevation terrain, large wind drifts need more time to stabilize on lee slopes steeper than 35 degrees.

Avalanche problems

  • Wind Slabs

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

    The damage has largely been done in terms of wind slab formation, although moderate winds and several inches of fresh snowfall through Thursday night won't help the healing process.  Large slabs lurk on a variety of lee slopes and are likely to be most reactive and prevalent at upper elevations. We have a lot of uncertainty around the size potential, sensitivity, and distribution throughout the terrain, but we do think most softer slabs at lower elevations should be healing up by Friday. How to manage the uncertainty? Assume wind-loaded slopes are guilty until proven innocent. Sharp cornices point toward the slopes where you're likely to find slabs. Less wind affected snow should be right-side-up, so firmer snow over lower density layers is your easiest way to confirm reactivity. The larger the density difference, the worse the problem. Cracks or collapses give you a warning before you move onto a steeper slope. Slabs could lurk far lower on a slope than you expect, so if head into wind-loaded terrain, give steeper slopes a safety margin, particularly those that are unsupported.

    Sensitive cornices may be prone to failure as the sun makes an appearance. These could trigger wind slabs on the slopes below. 

    Example: Large slab releases in heavily wind-stiffened snow like you might find on Friday.

    Photo: Koby Yudkin

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    A sharp shift to warmer conditions and filtered sunshine on Friday may destabilize deep, cold low-density snow. The January sunshine can really only do damage on steep slopes receiving direct sunshine. So, pay attention to the clock and the slopes above you. Snow will start shedding off rocks and cliffs as these features warm first. It may then start entraining moist or dry surface snow to form avalanches large enough to bury you, particularly around creek beds and other terrain traps. Rollerballs are yet another sign you should adjust your aspect and reduce your overhead hazard. In heavily wind-affected terrain, this problem may not materialize, so we're not sure whether you will encounter wet loose at upper elevations.

    Example: Surface wet or dry loose snow avalanches will become more dangerous the deeper they entrain recent snow.

    Photo: Peter Moore

Avalanche Discussion

So far, Mt. Hood has picked up 30" inches of snow since Tuesday, and a few more inches of snow will trickle in Tuesday night. While the wind slabs and warming trend are the major stories,  deep snow increases your risk of Snow Immersion and Suffociation, particularly around small trees and creeks. Keep this on your mind and keep your partner in constant contact. 

Strong and gusty winds were cranking on Mt Hood again on Thursday. Despite the winds, observers continued to find generally soft and right-side-up snow at lower and middle elevations. Wind slabs were generally limited to more specific terrain features and slabs were mostly of the soft variety, existing down to 5000 ft in the Timberline area. Mt Hood Meadows reported some some storm slabs that lacked cohesion and plenty of dry loose avalanche activity in sheltered terrain. Although dry loose and storm slab activity should fade as temperatures warm on Friday, keep these in mind. Ease onto smaller slopes with less consequence to start your day.

All the dry snow has our focus on the rapid rise in temperatures from the mid-20s to upper 30s over the next 24 hours. This warm-up is likely to drive the peak danger rating at lower and middle elevations.

The lower and middle snowpack remains strong, with primary concern above a prominent 1/3 rain crust. In many areas, you may also encounter a 1/6 sun crust on SW–S–SE aspects, overlain by 6–8 inches of consolidated snow. Recent reports have suggested a good bond to these crusts, but we have no information from higher on the mountain. You're likely to find 2-3 ft of snow overlying the uppermost crust by Friday. 

Shallowly buried obstacles remain widespread at lower and middle elevations, increasing consequences in both falls and avalanches.

Regions covered