Avalanche Forecast
Regions: Mt Hood.
Loose-wet snow avalanches should remain possible in steep terrain. Use caution in steep terrain, especially if the surface snow is wet more than a few inches, avoiding steep slopes above terrain hazards such as trees or cliffs. Avoid travel on or below cornices.
Detailed Forecast
Showers should remain light in most areas on Sunday except possibly in convergence in the central west Cascades with cooler temperatures.
This should not greatly change the regional avalanche danger on Sunday.
Expect shallow wet snow conditions over one or more strong near surface crust layers mainly on solar slopes near and below treeline.
Recent cornices are very large. Natural cornice releases and resulting slab avalanches are dangerous and unpredictable. Give cornices a wide berth if traveling along ridge-lines and avoid slopes below large cornices. See a blog post regarding cornices here.
Snowpack Discussion
Weather and Snowpack
Let's just say it's been a wet and wild few weeks regarding weather and avalanches in the Cascades.Â
Last week was also active weather-wise, but water amounts/snowfall totals were slightly lower relative to the extreme wetness of the past few weeks. In the last 5 days ending Monday morning NWAC stations at Mt Hood have picked up another 2-2.5 ft of snow.
A strong low pressure system brought rising snow levels and locally heavy precipitation Tuesday night through Wednesday along the west slopes of the Cascades including Mt. Hood. After receiving a few inches of snow Tuesday night, Mt. Hood saw periods of moderate to heavy rain to above 7000 feet on Wednesday.
Cooling and showery weather Thursday allowed wet snow to begin refreezing with an additional 1-5 inches accumulating in most areas. The strong winds began diminishing Thursday, but continued to transport new and available snow to lee slopes, building fresh wind slabs, mainly above treeline.
Very mild temperatures and strong sunshine Friday, allowed for wet surface snow conditions in most terrain, even northerly facing slopes. Shallow loose-wet snow avalanches occurred Friday on many steep slopes but remained small along with snowpack consolidation.
A weak front crossed the Northwest on Saturday morning causing light rain mainly along the Cascade west slopes.
Recent Observations
On Monday the Meadows pro-patrol found touchy 6-12"Â but up to 12-18"Â wind slab on NE slopes near and above treeline. Surface loose wet snow was also becoming evident in the below treeline areas.
The Meadows pro- patrol on Tuesday reported one explosive released 12-20 inch storm slab on an east slope at about 6000 ft. Patrollers also triggered a large cornice on approach. Surface snow was getting wet with some pinwheels in the afternoon.
The storm limited observations on Wednesday, but rain quickly penetrated the upper snowpack in the Mt. Hood Meadows base area by late morning.Â
NWAC pro-observer Laura Green was in the White River area in the 4500-6000 ft range on Friday and reported 4-13 cm of recent snow on the P crust from mid week. Pit tests gave hard results that did not indicate propagation on a layer at 30 cm. She noted natural wind  slab releases in the above treeline and loose wet avalanches below from Thursday.
The Meadows pro-patrol on Saturday reported triggered loose wet avalanches becoming possible on solar slopes. Otherwise the recent crust is the predominate snow surface there with small shallow areas of wind transported snow been soaked by rain and frozen in place.
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.
Elevations: Treeline, Below Treeline.
Likelihood: Possible
Expected Size: 1 - 1
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind lips of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
Cornices can never be trusted and avoiding them is necessary for safe backcountry travel. Stay well back from ridgeline areas with cornices. They often overhang the ridge edge can be triggered remotely. Avoid areas underneath cornices. Even small Cornice Fall can trigger a larger avalanche and large Cornice Fall can easily crush a human. Periods of significant temperature warm-up are times to be particularly aware.
A corniced ridgeline. A large cornice has formed at the top of the ridge. A smaller cornice has formed to the left of the trees from crossloading.
Cornices are easy to identify and are confined to lee and cross-loaded ridges, sub-ridges, and sharp convexities. They are easiest to trigger during periods of rapid growth (new snow and wind), rapid warming, and during rain-on-snow events. Cornices often catch people by surprise when they break farther back onto flatter areas than expected.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood: Unlikely
Expected Size: 1 - 2