Avalanche Forecast
Regions: Mt Hood.
The strong storms Saturday and Sunday have created widespread new storm layers and new unstable wind slab on many lee slopes, especially near ridges. Travel conservatively by staying off or below steeper slopes and avoid wind loaded terrain, especially but not limited to N-SE facing terrain.
Detailed Forecast
A few isolated snow showers may linger Monday, while winds should be light and temperatures remain cool.Â
This should allow for a slowly improving avalanche danger as recent storm and wind slabs begin settling and stabilizing.
However, storm and wind slab conditions should remain sensitive or still likely to trigger in specific areas and more widespread areas near and above treeline. A variety of slopes may be wind loaded due to the local effects of terrain, however, in general wind loaded slopes should range from north to southeast facing. Â
Dangerous avalanche conditions are expected near and above tree line requiring conservative decision-making and cautious routefinding.
Be cautious with any steeper open terrain suspected of recent wind loading, leaving those more exposed features a wide margin of safety.
Travel conservatively by staying off, or below steep open slopes and avoiding the wind loaded terrain near and above treeline.
Be aware of early season hazards below treeline. The heavy rains from last week have left many creeks open at lower elevations.Â
Snowpack Discussion
After the deluge earlier in this week with nearly a foot of rain below 7000 feet, winter has returned to Mt Hood with lower snow levels and lots of new as of Sunday afternoon. About a foot of new snow fell over the 24 hours ending 5 pm Friday, with about 1-2 more feet of snow accumulating by Sunday afternoon. Â
Avalanche and Snowpack Observations
The Mt Hood Pro Patrol on Sunday reported sensitive explosive releases on most lee slopes up to 6600 feet as travel above that was avoided. Numerous soft slabs ran 100% of the paths and travelled far distances, releasing in storm layer weaknesses. These slides were on previously heavily skied paths, indicating backcountry areas would likely have significantly deeper slab potential. NWAC Mt Hood area observer Laura Green traveled to 6500 ft in the Bucket Creek drainage Friday, indicating about 40 cm (16 inches) of new storm snow had accumulated over the newly forming pencil hard crust. No significant storm snow related weaknesses were yet observed with only stubborn test results noted. However, it was felt those conditions would rapidly deteriorate with Saturday's expected storm, which has certainly arrived! Below treeline should still contain ample terrain anchors, but above 5000' there is enough snow to allow small avalanches in specific areas. No recent observations have been received for the bulk of the above treeline zone due to weather and visibility restrictions.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: Likely
Expected Size: 1 - 1
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: Possible
Expected Size: 1 - 1