Avalanche Forecast
Regions: Mt Hood.
Lingering wind slab on lee slopes near and above treeline may be tougher to trigger, but still possible on Sunday. Wet loose avalanche will be most likely on steeper solar slopes. Moderate avalanche danger means heightened avalanche conditions (hazard) on specific terrain features, so match your terrain selection to the avalanche problems.
Detailed Forecast
A warm front lifting north across the area should bring clouds to Mt. Hood Sunday morning followed by a clearing trend in the afternoon. A significant warming trend will begin Sunday but will likely be tempered by moderate winds above treeline. Â
Lingering wind slab on lee slopes in the near and above treeline elevation bands may be tougher to trigger, but still possible Sunday. Watch for signs of snowpack cracking and firmer wind transported snow on lee slopes.
Wet loose avalanche will be most likely on steeper solar slopes. Be aware of loose wet avalanche potential above terrain traps (like above cliffs or near gullies), where even small wet avalanches can become powerful and have unintended consequences. Â
Snowpack Discussion
Weather and Snowpack
A strong occluded front with strong winds crossed the Northwest January 29-30th. NWAC stations on Mt Hood received about 1.5 feet of new snow
Cool and benign weather settled over Mt. Hood Sunday to Tuesday with ample sunshine on Tuesday. A sun crust likely formed on solar slopes.
A cold front and then a warm front crossed the Northwest on Wednesday and Thursday. NWACÂ stations at Mt Hood for the 2 days ending Friday morning had 18-20 inches of snowfall.
Friday saw a warm system with strong winds bring rain up to near treeline (above 5000 feet) on Mt. Hood before cooling Friday night and depositing about 3 inches of new snow.
Recent Observations
The Meadows pro-patrol Thursday reported heavy snowfall and remotely and easily triggered widespread 1 foot wind slab mainly on north to southeast slopes along with storm slab in the near and above treeline. A combination of storm slab, loose wet avalanches and rollerballs was seen below treeline.
A couple reports for Mt Hood are available via the NWAC Observations page from Mt Hood on Thursday with easy pit tests for storm layers or on the crust buried January 29th. Roller balls due to warm temperatures were reported below the snow level.
The Meadows pro-patrol reported less activity Friday with isolated wind or storm slab released by explosives or ski cuts in the near and above tree line.
Large wind slabs were triggered with explosives above treeline by Meadows pro-patrol Saturday morning on lee slopes. Near treeline, cross loaded gullies were sensitive to skier triggering with 1 ft slabs possible. A breakable crust dominated below treeline Saturday. 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.
Elevations: Alpine, Treeline.
Likelihood: Possible
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.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 1