Avalanche Forecast
Regions: Mt Hood.
This is a time of the year when you often need to watch for both winter and spring types of avalanche conditions. It is always good to read the forecast for details.
Detailed Forecast
A period of northeast ridge top winds and east pass winds should be seen in the Cascades this afternoon and tonight.
Then decreasing winds and sunny weather should be seen in the Cascades on Tuesday.
Watch for new shallow wind transported snow on unusual south to west facing slopes on Tuesday. Older wind slab from February 27th-28th is also most likely to linger on similar slopes.
The sun will be out full on and stronger and the days are getting longer so keep an eye on solar slopes for wet snow and signs of loose wet snow on solar slopes on Tuesday.
Due to the low snowpack, especially below treeline, watch for terrain hazards such as open creeks, partially covered rocks and vegetation. Many areas below treeline do not have enough snow (new or existing) to pose an avalanche hazard.Â
Snowpack Discussion
The latest snowfall in the Cascades was February 25-27th when about 4-10 inches fell near and above treeline at Mt Hood.
This was followed by strong northeast winds in the Cascades and at Mt Hood February 27-28th.
The Mt Hood Meadows patrol, on the morning of February 27th, reported sensitive new wind slab at about 6600 feet on northeast slopes with soft wind slabs around 1 foot easily releasing.Â
By February 28th the recent surface snow had been stripped from most slopes above 6500 feet. The winds were so strong to have blasted the shallow surface snow to who knows where, rather than steadily building new wind slab layers. Nonetheless pockets of wind slab will need to be watched for on a variety of terrain features.
The mid and lower snowpack at Mt Hood snow consists of layers of stable consolidated rounded grains or melt forms and crusts from multiple warm periods this winter.
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: South, South West, West, North West.
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: South East, South, South West.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 1