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Avalanche Forecast

Archived

Feb 15th, 2016–Feb 16th, 2016

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

Regions

Mt Hood.

A mixed bag of conditions seems possible on Tuesday with winter like snow conditions possible in the above treeline and wet snow conditions in the near and below treeline.

Detailed Forecast

A weak cold front will cause rain or snow to shift from north to south over the Olympics and Cascades tonight to Tuesday morning with a slight drop in snow levels. A couple or a few inches of snow should be seen in the above treeline at Mt Hood with some more rain in the near and below tree line.

Another weak warm front should lift south to north over the Northwest Tuesday afternoon and night and cause light rain or snow with another slight rise in snow levels.

A mixed bag of conditions seems possible on Tuesday with shallow winter like snow conditions possible in the above treeline and wet snow persisting in the near and below treeline.

Watch for new shallow firmer wind transported snow above tree line mainly on lee N to SE slopes near ridges. You will need to be able to assess this problem for yourself if you travel above treeline on Tuesday.

You should continue to watch for loose wet avalanche conditions in the near and below treeline on Tuesday. Watch for wet surface snow deeper than a few inches that usually precede loose wet avalanches or other triggered or natural loose wet avalanches. Steep slopes near and below treeline are probably still best avoided on Tuesday.

 

Snowpack Discussion

Weather and Snowpack

Dry weather with the warmest temperatures of the winter occurred last Sunday to Wednesday with temperatures climbing into the 50's and even the 60's.

A pair of warm fronts brought about 9-15 inches of new snow to Mt Hood about Thursday to Saturday.

Rain and and mild temperatures predominated along the west slopes Sunday and today. NWAC sites at Mt Hood will have had rain in the 2.5 inch range for the 2 days ending Tuesday morning.

Bonds should be good in the upper snowpack along the west slopes. The mid and lower snowpack should be mostly consolidated and stable.

Recent Observations

The Mt Hood Meadows pro-patrol reported a widespread natural cycle of loose wet avalanches on Sunday morning. Today no avalanches were reported with consolidated snow and surface runnels up to 7000 feet.

Problems

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.

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.