Avalanche Forecast
Regions: Mt Hood.
A MODERATE danger means human triggered avalanches are possible. Watch mainly for possible wind slab on a variety of aspects and for possible loose wet avalanches on steep solar slopes. Watch out for dangerous tree bombs and stay in sight of your partner.
Detailed Forecast
Sunny weather should be seen on Thursday.
This weather should allow older wind slab to continue to slowly settle and stabilize. Wind slab will most likely be found on north to southeast aspects near and above tree line. Any wind slab avalanches should be confined to surface layers. Watch and test for inverted strong over weak storm snow.
The sunny weather could bring the possibility of loose wet avalanches Thursday afternoon on steep solar slopes. Watch for surface wet snow deeper than a few inches, initial roller balls and natural loose wet avalanches on steep solar slopes where snow may shed from rocks or cliffs.
A lot of snow has been seen in trees lately along the west slopes. Stay away from trees if you see trees starting to shed snow due to sunny weather on Thursday afternoon. A tree bomb can be just as fatal as an avalanche!
There have been snow immersion fatalities in tree wells already this season at Snoqualmie and in Canada. Tree wells may still be lurking so stick near your partner in the trees and maintain visual contact. Â
Snowpack Discussion
A cool very snowy storm cycle brought 6-7 feet of snowfall to Mt Hood the week ending December 24th. Moderate additional accumulations in the past week have allowed the snowpack to slowly settle with good skiing. A weak weather system Sunday and Monday helped create some new mostly small and mostly shallow wind slab in many areas of the Cascades.
The most recent control work with explosives on Christmas by the Mt Hood Meadows pro patrol triggered large avalanches on specific wind loaded slopes near treeline that stepped down to the December 17th rain crust. However, these results were not repeatable on other slopes of similar aspect and elevation with larger explosives.
LIttle has been reported from Mt Hood since then so the ease of triggering seems to be diminishing. Storm slabs have all but settled and are no longer a problem of note. Storm snow has been gradually settling but remains mostly right side up and continues to offer some excellent conditions.
The Mt Hood Meadow pro patrol reported an overall right side up upper snow pack, good stability, limited wind effects below 7500 feet and good skiing on Tuesday.
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Avalanche Problems
Wind Slabs
Release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Wind Slabs form in specific areas, and are confined to lee and cross-loaded terrain features. They can be avoided by sticking to sheltered or wind-scoured areas..
Wind Slab avalanche. Winds blew from left to right. The area above the ridge has been scoured, and the snow drifted into a wind slab on the slope below.
Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.
Aspects: North, North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1
Loose Wet
Release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. They generally move slowly, but can contain enough mass to cause significant damage to trees, cars or buildings. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
Travel when the snow surface is colder and stronger. Plan your trips to avoid crossing on or under very steep slopes in the afternoon. Move to colder, shadier slopes once the snow surface turns slushly. Avoid steep, sunlit slopes above terrain traps, cliffs areas and long sustained steep pitches.
Several loose wet avalanches, and lots of pinwheels and roller balls.
Loose wet avalanches occur where water is running through the snowpack, and release at or below the trigger point. Avoid terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or during rain-on-snow events.
Likelihood: Possible
Expected Size: 1 - 1