Avalanche Forecast
Regions: Mt Hood.
Back country travel will require cautious route finding and careful snowpack evaluation at Mt Hood on Wednesday.
Detailed Forecast
Strong southwest flow aloft will carry a very moist frontal system to the Northwest on Wednesday. This will cause stormy wet weather along the Cascade west slopes on Wednesday with rain and high snow levels. The most rain should be seen in the Washington Cascades. See the NWAC Mountain Weather Forecast for details.
Dangerous avalanche conditions are possible at Mt Hood on Wednesday. Natural or triggered loose wet and wet slab avalanches are possible on Wednesday depending on how much rain there is, how it percolates into the snowpack and if avalanches entrain deeper layers.
Observations and tests for loose wet avalanches are more straightforward such as wet surface snow deeper than a few inches, rollerballs and natural loose wet avalanche actiivity.
But observations and tests for wet slab avalanches are more difficult since it is usually hard to know the effects of significant amounts of water percolating into the snowpack.
Cautious route finding and careful snowpack evaluation will be required if you decide to travel in the back country at Mt Hood on Wednesday.
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Snowpack Discussion
Weather and Snowpack
The aftermath of the last storm cycle 2/8-2/10 left a very strong rain crust with whatever amount of new snow received above, except for areas exposed to west winds which remained scoured to the firm and slick crust. Â
High pressure Saturday to Tuesday brought increasing sunshine and warm temperatures. Temperatures reached the 40's and 50's in many areas of the Olympics and Cascades by Monday and Tuesday. This caused a lot of snowpack settlement, some small loose wet avalanche activity and a decreasing avalanche danger.
Recent Observations
A very large 6-8 foot slab avalanche released sometime last week likely 2/8-2/10Â from about the 8000 foot level in Newton Canyon.
On Friday 2/10 the Meadows pro-patrol reported widespread loose wet and small wet slab natural activity had occurred Thursday near and above treeline. One very large wet slab occurred in the God’s Wall path up to size D3, likely releasing sometime Thursday.  Below treeline a saturated snowpack was still re-freezing and became less supportable at lower elevations.
Otherwise the Meadows pro-patrol reported only some rollerballs and no significant avalanche activity on Monday and Tuesday.
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: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 1
Wet Slabs
Release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slab avalanches can be very destructive.
Avoid terrain where and when you suspect Wet Slab avalanche activity. Give yourself a wide safety buffer to handle the uncertainty
A Wet Slab avalanche. In this avalanche, the meltwater pooled above a dusty layer of snow. Note all the smaller wet loose avalanches to either side.
Wet slabs occur when there is liquid water in the snowpack, and can release during the first few days of a warming period. Travel early in the day and avoiding avalanche paths when you see pinwheels, roller balls, loose wet avalanches, and during rain-on-snow events.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 1