Avalanche Forecast
Regions: Mt Hood.
New small shallow storm and wind slab seem possible by the end of the day at Mt Hood on Monday. Evaluate snow and terrain carefully on Monday. Adjust your plans if winds are stronger or new snowfall is heavier than expected.
Detailed Forecast
A front should weaken as it moves over the Northwest on Monday. At Mt Hood this should bring moderately increasing southwest alpine winds and light occasional moderate rain or snow Monday morning changing to showers Monday afternoon with lowering snow levels.
Wet surface snow from Sunday should refreeze on Monday.Â
New small areas of shallow storm slab seem possible mainly on the volcanoes. The limited amounts of new snow and the cooling trend should limit the extent and depth of new storm slab by the end of the day.
New small areas of shallow wind slab also seem possible mainly on lee slopes on the volcanoes by the end of the day. The limited amounts of new snow and the cooling trend should also limit the extent and depth of new wind slab.
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Snowpack Discussion
About a week of fair weather was centered around the New Year. This allowed the heavy snow that fell during the strong storm cycle that ended about Christmas to settle and stabilize.
By New Years Eve through last weekend moderate to strong east-northeast winds had significantly scoured most of the available surface snow, mainly in the near and above treeline elevation bands.
Surface snow sculpted by recent wind and active wind transport. Photo: Laura Green
Last Monday the Mt Hood Meadows pro patrol reported warming and a widespread 1 cm freezing rain crust up to 7000 feet. This was followed by about 8-10 inches of snow at Mt Hood early last week.
Laura was out again near the Mt Hood Meadows ski area last week and reported 5 inches of storm snow had formed small slabs, non-reactive to ski cuts, but some explosive triggered slides up to 10 inches were seen on steep slopes of varied aspects. These shallow slabs were becoming less sensitive by Wednesday.
No avalanches have been reported over the past several days on Mt Hood.
Avalanche Problems
Storm Slabs
Release of a soft cohesive layer (a slab) of new snow that breaks within the storm snow or on the old snow surface. Storm-slab problems typically last between a few hours and few days. Storm-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.
You can reduce your risk from Storm Slabs by waiting a day or two after a storm before venturing into steep terrain. Storm slabs are most dangerous on slopes with terrain traps, such as timber, gullies, over cliffs, or terrain features that make it difficult for a rider to escape off the side.
Storm slabs usually stabilize within a few days, and release at or below the trigger point. They exist throughout the terrain, and can be avoided by waiting for the storm snow to stabilize.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1
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