Avalanche Forecast
Regions: Mt Hood.
Although less likely, the primary avalanche problems Thursday will continue to be loose wet avalanches near and above treeline and lingering wind slab on lee aspects above treeline.
Detailed Forecast
Mild freezing levels will prevail again on Thursday with high overcast and occasional sunbreaks forecast.Â
Loose wet avalanches are possible Thursday on steeper solar slopes near and above treeline that receive substantial sun breaks.  Â
Lingering wind slab will be listed as a problem for one more day above treeline. Watch for firmer wind transported snow on previous lee slopes, mainly on N-SE slopes near ridges.
As a result of the overall low snowpack, especially below treeline, watch for terrain hazards such as open creeks, partially covered rocks and vegetation.
Snowpack Discussion
The latest atmospheric river to impact the Pacific Northwest brought less rain to Mt. Hood versus areas further north late last week. This event led to overall snowpack settlement, and at lower elevations, continued melting of the seasonal snowpack.  Â
The last frontal system crossed the south Cascades late Monday. This caused strong winds and heavy snow in the above treeline zone at Mt Hood.
On Tuesday, the Meadow pro-patrol reported 15 inches of new snow at 6600 feet. Avalanche control gave numerous size 1-2 wind and storm slab avalanches on lee slopes but with limited propagation. Similar wind slab concerns were reported on lee east aspects west of Timberline Tuesday on the NWAC observation page. Â
On Wednesday, Mt. Hood Meadows pro-patrol reported high overcast had limited the loose wet potential on an otherwise mild winter's day, and no new avalanches were observed.Â
The mid and lower snowpack at Mt Hood should consist of layers of stable consolidated rounded grains or melt forms and crusts from multiple warm periods this winter.
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: South East, South, South West, West.
Elevations: All elevations.
Likelihood: Possible
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: North, North East, East, South East.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1 - 1