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Avalanche Forecast

Archived

Mar 22nd, 2015–Mar 23rd, 2015

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Mt Hood.

There may be some shallow storm and wind slab above treeline Monday. Any new snow that does fall will be susceptible to sun breaks later Monday afternoon, so use extra caution on steeper solar slopes near and above treeline. 

Detailed Forecast

 

Light to moderate showers are expected as an upper trough passes Monday. Freezing levels should lower Monday, but be tapered by daytime warming.  Increasing SW ridge top winds may build shallow new wind slabs on some lee slopes, mainly below ridges on N-NE facing terrain near and above treeline. 

Any new snow that does fall will be susceptible to sun breaks later Monday afternoon, so use extra caution on steeper solar slopes above treeline. 

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

About two inches of mainly rain fell at Mt. Hood a week ago Saturday, followed by only a few inches of snow 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.   

The most recent frontal systems Friday night and again Sunday deposited about 4-6 inches of snow from about 6000 feet and above, with slightly 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.

No additional avalanche activity was reported Sunday by Meadows patrol.

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.

Problems

Loose Wet

Loose Wet avalanches are the 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. 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.

Wind Slabs

Wind Slab avalanches are the 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.