Avalanche Forecast
Regions: Mt Hood.
Warming with heavy rain and snow and very strong winds is causing a widespread avalanche cycle Saturday. Rapidly increasing avalanche danger is creating very dangerous avalanche conditions. Large to very large and destructive avalanches may run long distances to lower elevations. Travel in avalanche terrain not recommended Saturday.
Detailed Forecast
Update 8:00 AM - Warming and heavy rain and snow with stormy conditions has caused a rapid increase in avalanche danger in the Mt Hood area. Â
Large natural avalanches are likely in many areas Saturday and back country travel in avalanche terrain is not recommended.
Near and above treeline winds will continue to build on already sensitive wind slabs. As sensitive wind layers become buried deeper, they will become more difficult to trigger but can still result in a large and destructive avalanche. Identify and avoid firm wind deposited snow. Â
Relatively warmer temperatures, gusty winds and occasional showers will make triggering storm slabs easier. As snow showers change to rain showers at lower elevations, expect loose dry avalanches to transition to loose wet on steeper slopes. Be aware of the consequences of a loose avalanche above terrain traps.Â
With all the new snow, this is a time to stick to safer terrain. Utilize low angle slopes, and be aware of terrain above you. Large avalanches may originate at higher elevations and travel to runouts even below treeline.
Snow conditions changed significantly during this extended storm cycle. Tree-well and snow immersion hazards are very dangerous. Keep communication with your partner at all times.
Snowpack Discussion
Update 8:00 AM - Warming and heavy rain and snow with very strong winds have caused a natural avalanche cycle Saturday morning. Snow changing to rain up to about 5000-5500 ft, heavy, dense wind driven snow has loaded existing weak snow causing a rapid increase in the avalanche danger in the Mt Hood area Saturday morning. Travel in avalanche terrain is not recommended Saturday. Some avalanches may become large to very large and run long distances.  Â
A very active weather pattern continues to impact the Mt Hood area. Approximately 30 inches of settled snow now sits on top of the 1/18 crust. Fluctuations in precipitation intensity and temperature seen throughout the storm cycle created several sensitive storm layers within the new snow. Depth and sensitivity of these layers varies depending on location and elevation.
Moderate winds over the last eight days redistributed snow on exposed features near and above treeline. Shifts in wind direction created wind slabs on a variety of aspects.
With the ongoing storm cycle, direct observations above treeline have been hard to come by. A high level of uncertainty exists above treeline.Â
Observations
Update 8:00 AM - Mt Hood professional patrol report natural avalanches occurring Saturday morning at elevations below treeline. Warming with continued heavy wet snow or snow changing to rain was reported Saturday morning, with natural avalanches reported.
NWAC pro-observer Laura Greene was in the Newton Creek drainage Friday. She encountered low visibility with lots of new snow and wind transportation. Observations found 2.5 feet of storm snow.Â
On Friday, Mt. Hood Meadows patrol reported 2-6" sensitive wind slabs during control work near treeline. Below treeline, snow was generally right-side up and no reactive storm layers were noted. No observations were made above treeline.Â
On Wednesday, a professional ski patroller was caught, carried, and partially buried in an avalanche he triggered while on duty in a closed area of the Mt. Hood Meadows ski area (SS-AS-R2-D2-I). The avalanche released in an area known as God's Wall, running approximately 600 ft on the old/new snow interface. The bed surface was the firm 1/18 crust. Resources were dispatched immediately and the victim extricated after some difficulty due to low snow and open creeks. He was transported via ambulance to advanced care and is now discharged to recover from his injuries.
Avalanche Problems
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
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: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 2
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