Avalanche Forecast
Regions: Mt Hood.
Travel in avalanche terrain is not recommended Thursday, especially near and above treeline where larger and more dangerous avalanches are possible.
Detailed Forecast
A strong Pacific frontal system on Thursday should bring heavy precipitation to the Mt. Hood area along with a strong warming trend. Â
As snowfall and winds increase, avoid steeper slopes and watch for increasingly sensitive storm layers. A rising rain-line should also activate storm slabs throughout the day. At lower elevations that change to rain quickly, watch for small loose wet avalanches on steeper slopes and near terrain traps.Â
New and recent snow will be deposited on lee NW through SE aspects near and above treeline. Most avalanches should stay within the new storm snow, but some may step down to older storm layers or crusts producing larger avalanches.  Â
Travel in avalanche terrain is not recommended Thursday due to dangerous avalanche conditions, especially near and above treeline.Â
The elevated avalanche danger will continue Thursday night into Friday morning. Â
Terrain anchors are still causing significant anchoring at the lowest elevations. Use caution near creeks which are still open in some areas.
Snowpack Discussion
An atmospheric river around Dec 9th pushed heavy rain up well above 7000 feet in the Mt. Hood area. Below these elevations water percolated down below the early December crust (date at which when the crust was buried). An active and cool weather pattern over the last week has produced about 2 to 4 plus feet of new snowfall that now sits over the 12/9 crust. The below treeline zone snowdepth is filling in nicely but still contains many barely hidden hazards like rocks, streams or snags. The skiing in non-wind affected areas with enough snow cover has been good!Â
The Meadows pro patrol on Sunday reported sensitive explosive releases on most lee slopes up to 6600 feet. Numerous soft slabs ran their full paths, releasing in storm layers. The Meadows pro patrol on Monday still reported avalanches of increasing size with increasing elevation. At 6800 feet, avalanche control triggered a 3-5 foot hard wind slab on a northeast slope which released on the rain crust from last week. Ski cuts generally produced isolated 6-8 inch releases. The Meadows pro patrol on Tuesday reported that wind Monday night had greatly rearranged the snow into sastrugi and wind slab down to the below tree line zone but no new avalanches were triggered or reported.  W through NW winds above treeline may have further loaded lee slopes Tuesday night and early Wednesday. Â
Avalanche Problems
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, North West.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 2
Storm Slabs
Release of a soft cohesive layer (a slab) of new snow that breaks within the storm snow or on the old snow surface. Storm-slab problems typically last between a few hours and few days. Storm-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.
You can reduce your risk from Storm Slabs by waiting a day or two after a storm before venturing into steep terrain. Storm slabs are most dangerous on slopes with terrain traps, such as timber, gullies, over cliffs, or terrain features that make it difficult for a rider to escape off the side.
Storm slabs usually stabilize within a few days, and release at or below the trigger point. They exist throughout the terrain, and can be avoided by waiting for the storm snow to stabilize.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Very Likely
Expected Size: 1 - 1
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: Below Treeline.
Likelihood: Likely
Expected Size: 1 - 1