Avalanche Forecast
Regions: Mt Hood.
There may be some shallow storm and wind slab above treeline Sunday. Any new snow that does fall will be susceptible to sunbreaks later Sunday afternoon, so use extra caution on steeper solar slopes near and above treeline.
Detailed Forecast
A frontal system will bring renewed light rain and snow to the Mt Hood area Sunday followed by showers Sunday afternoon. Increasing southwest ridge top winds may build new wind slabs on lee slopes, mainly northerly to easterly facing near and above treeline.Â
Any new snow that does fall will be susceptible to sunbreaks later Sunday afternoon, so use extra caution on steeper solar slopes above treeline.Â
Due to the low snowpack, especially below treeline, watch for terrain hazards such as open creeks, partially covered rocks and vegetation. Many areas below treeline do not have enough snow to cause an avalanche danger.
Snowpack Discussion
After roughly two inches of mainly rain fell at Mt. Hood on Saturday March 14th, only a few inches of snow accumulated above 6000 feet last Sunday and Tuesday. No new avalanches or layers of concern have been reported during an otherwise benign and generally mild week of weather.  Â
A front Friday night and a few showers early Saturday deposited about a few inches of new snow, with a little greater amounts near and above 6600 feet at Mt Hood Meadows as reported by the pro patrol Saturday. The new snow and winds did build some stiff wind slab on NE aspects, mainly about 4-6 inches but up to 1 foot in places. These very stiff slabs were unreactive to ski cutting as the new snow fell on old wet snow and formed a good bond and thus were resistant to triggers.
The mid and lower snowpack at Mt Hood consists of layers of stable consolidated rounded grains or melt forms and crusts from multiple warm periods this winter. The snowpack at low elevations remains meager to non-existent.
Avalanche Problems
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.
Aspects: South East, South, South West, West.
Elevations: Alpine, Treeline.
Likelihood: Unlikely
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.
Likelihood: Unlikely
Expected Size: 1 - 1